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Amaya FA, Blondel CJ, Reyes-Méndez F, Rivera D, Moreno-Switt A, Toro M, Badilla C, Santiviago CA, Pezoa D. Genomic analysis of Salmonella isolated from surface water and animal sources in Chile reveals new T6SS effector protein candidates. Front Microbiol 2024; 15:1496223. [PMID: 39723139 PMCID: PMC11669294 DOI: 10.3389/fmicb.2024.1496223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2024] [Accepted: 11/12/2024] [Indexed: 12/28/2024] Open
Abstract
Type VI Secretion Systems (T6SS), widely distributed in Gram-negative bacteria, contribute to interbacterial competition and pathogenesis through the translocation of effector proteins to target cells. Salmonella harbor 5 pathogenicity islands encoding T6SS (SPI-6, SPI-19, SPI-20, SPI-21 and SPI-22), in which a limited number of effector proteins have been identified. Previous analyses by our group focused on the identification of candidate T6SS effectors and cognate immunity proteins in Salmonella genomes deposited in public databases. In this study, the analysis was centered on Salmonella isolates obtained from environmental sources in Chile. To this end, bioinformatics and comparative genomics analyses were performed using 695 genomes of Salmonella isolates representing 44 serotypes obtained from surface water and animal sources in Chile to identify new T6SS effector proteins. First, T6SS gene clusters were identified using the SecreT6 server. This analysis revealed that most isolates carry the SPI-6 T6SS gene cluster, whereas the SPI-19 and SPI-21 T6SS gene clusters were detected in isolates from a limited number of serotypes. In contrast, the SPI-20 and SPI-22 T6SS gene clusters were not detected. Subsequently, each ORF in the T6SS gene clusters identified was analyzed using bioinformatics tools for effector prediction, identification of immunity proteins and functional biochemical prediction. This analysis detected 20 of the 37 T6SS effector proteins previously reported in Salmonella. In addition, 4 new effector proteins with potential antibacterial activity were identified in SPI-6: 2 Rhs effectors with potential DNase activity (PAAR-RhsA-NucA_B and PAAR-RhsA-GH-E) and 2 effectors with potential RNase activity (PAAR-RhsA-CdiA and RhsA-CdiA). Interestingly, the repertoire of SPI-6 T6SS effectors varies among isolates of the same serotype. In SPI-19, no new effector protein was detected. Of note, some Rhs effectors of SPI-19 and SPI-6 present C-terminal ends with unknown function. The presence of cognate immunity proteins carrying domains present in bona fide immunity proteins suggests that these effectors have antibacterial activity. Finally, two new effectors were identified in SPI-21: one with potential peptidoglycan hydrolase activity and another with potential membrane pore-forming activity. Altogether, our work broadens the repertoire of Salmonella T6SS effector proteins and provides evidence that SPI-6, SPI-19 and SPI-21 T6SS gene clusters harbor a vast array of antibacterial effectors.
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Affiliation(s)
- Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos J. Blondel
- Facultad de Medicina y Facultad de Ciencias de la Vida, Instituto de Ciencias Biomédicas, Universidad Andrés Bello, Santiago, Chile
| | - Felipe Reyes-Méndez
- Núcleo de Investigación en One Health, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
| | - Dácil Rivera
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Andrea Moreno-Switt
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Magaly Toro
- Joint Institute for Food Safety and Applied Nutrition (JIFSAN), University of Maryland, College Park, MD, United States
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile
| | - Consuelo Badilla
- Núcleo de Investigación en One Health, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - David Pezoa
- Núcleo de Investigación en One Health, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
- Departamento de Ciencias Químicas y Biológicas, Universidad Bernardo O'Higgins, Santiago, Chile
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2
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Han J, Tang H, Zhao S, Foley SL. Salmonella enterica virulence databases and bioinformatic analysis tools development. Sci Rep 2024; 14:25228. [PMID: 39448688 PMCID: PMC11502889 DOI: 10.1038/s41598-024-74124-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Accepted: 09/24/2024] [Indexed: 10/26/2024] Open
Abstract
Salmonella enterica, a prominent foodborne pathogen, contributes significantly to global foodborne illnesses annually. This species exhibits significant genetic diversity, potentially impacting its infectivity, disease severity, and antimicrobial resistance. Whole genome sequencing (WGS) offers comprehensive genetic insights that can be utilized for virulence assessment. However, existing bioinformatic tools for studying Salmonella virulence have notable limitations. To address this gap, a Salmonella Virulence Database with a non-redundant, comprehensive list of putative virulence factors was constructed. Two bioinformatic analysis tools, Virulence Factor Profile Assessment and Virulence Factor Profile Comparison tools, were developed. The former provides data on similarity to the reference genes, e-value, and bite score, while the latter assesses the presence/absence of virulence genes in Salmonella isolates and facilitates comparison of virulence profiles across multiple sequences. To validate the database and associated bioinformatic tools, WGS data from 43,853 Salmonella isolates spanning 14 serovars was extracted from GenBank, and WGS data previously generated in our lab was used. Overall, the Salmonella Virulence database and our bioinformatic tools effectively facilitated virulence assessment, enhancing our understanding of virulence profiles among Salmonella isolates and serovars. The public availability of these resources will empower researchers to assess Salmonella virulence comprehensively, which could inform strategies for pathogen control and risk evaluations associated with human illnesses.
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Affiliation(s)
- Jing Han
- Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR, 72079, USA.
- Division of Microbiology, National Center of Toxicological Research, Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR, 7209, USA.
| | - Hailin Tang
- Division of Bioinformatics and Biostatistics, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Shaohua Zhao
- Office of Applied Science, Center for Veterinary Medicine, Food and Drug Administration, Laurel, MD, 20708, USA
| | - Steven L Foley
- Division of Microbiology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR, 72079, USA.
- Division of Microbiology, National Center of Toxicological Research, Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR, 7209, USA.
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3
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Inpanathan S, Ospina-Escobar E, Li VC, Adamji Z, Lackraj T, Cho YH, Porco N, Choy CH, McPhee JB, Botelho RJ. Salmonella actively modulates TFEB in murine macrophages in a growth-phase and time-dependent manner. Microbiol Spectr 2024; 12:e0498122. [PMID: 38051049 PMCID: PMC10783059 DOI: 10.1128/spectrum.04981-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 11/01/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE Activation of the host transcription factor TFEB helps mammalian cells adapt to stresses such as starvation and infection by upregulating lysosome, autophagy, and immuno-protective gene expression. Thus, TFEB is generally thought to protect host cells. However, it may also be that pathogenic bacteria like Salmonella orchestrate TFEB in a spatio-temporal manner to harness its functions to grow intracellularly. Indeed, the relationship between Salmonella and TFEB is controversial since some studies showed that Salmonella actively promotes TFEB, while others have observed that Salmonella degrades TFEB and that compounds that promote TFEB restrict bacterial growth. Our work provides a path to resolve these apparent discordant observations since we showed that stationary-grown Salmonella actively delays TFEB after infection, while late-log Salmonella is permissive of TFEB activation. Nevertheless, the exact function of this manipulation remains unclear, but conditions that erase the conditional control of TFEB by Salmonella may be detrimental to the microbe.
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Affiliation(s)
- Subothan Inpanathan
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Erika Ospina-Escobar
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Vanessa Cruz Li
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Zainab Adamji
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Tracy Lackraj
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Youn Hee Cho
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Natasha Porco
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Christopher H. Choy
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Joseph B. McPhee
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Roberto J. Botelho
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada
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Kjellin J, Lee D, Steinsland H, Dwane R, Barth Vedoy O, Hanevik K, Koskiniemi S. Colicins and T6SS-based competition systems enhance enterotoxigenic E. coli (ETEC) competitiveness. Gut Microbes 2024; 16:2295891. [PMID: 38149626 PMCID: PMC10761095 DOI: 10.1080/19490976.2023.2295891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 12/13/2023] [Indexed: 12/28/2023] Open
Abstract
Diarrheal diseases are still a significant problem for humankind, causing approximately half a million deaths annually. To cause diarrhea, enteric bacterial pathogens must first colonize the gut, which is a niche occupied by the normal bacterial microbiota. Therefore, the ability of pathogenic bacteria to inhibit the growth of other bacteria can facilitate the colonization process. Although enterotoxigenic Escherichia coli (ETEC) is one of the major causative agents of diarrheal diseases, little is known about the competition systems found in and used by ETEC and how they contribute to the ability of ETEC to colonize a host. Here, we collected a set of 94 fully assembled ETEC genomes by performing whole-genome sequencing and mining the NCBI RefSeq database. Using this set, we performed a comprehensive search for delivered bacterial toxins and investigated how these toxins contribute to ETEC competitiveness in vitro. We found that type VI secretion systems (T6SS) were widespread among ETEC (n = 47). In addition, several closely related ETEC strains were found to encode Colicin Ia and T6SS (n = 8). These toxins provide ETEC competitive advantages during in vitro competition against other E. coli, suggesting that the role of T6SS as well as colicins in ETEC biology has until now been underappreciated.
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Affiliation(s)
- Jonas Kjellin
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Danna Lee
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Hans Steinsland
- CISMAC, Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Rachel Dwane
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Oda Barth Vedoy
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Kurt Hanevik
- Department of Clinical Science, University of Bergen, Bergen, Norway
- National centre for Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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5
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Kalindamar S, Abdelhamed H, Kordon AO, Tekedar HC, Pinchuk L, Karsi A. Characterization of Type VI secretion system in Edwardsiella ictaluri. PLoS One 2023; 18:e0296132. [PMID: 38153949 PMCID: PMC10754466 DOI: 10.1371/journal.pone.0296132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 12/06/2023] [Indexed: 12/30/2023] Open
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular fish pathogen causing enteric septicemia of catfish (ESC). While various secretion systems contribute to E. ictaluri virulence, the Type VI secretion system (T6SS) remains poorly understood. In this study, we constructed 13 E. ictaluri T6SS mutants using splicing by overlap extension PCR and characterized them, assessing their uptake and survival in channel catfish (Ictalurus punctatus) peritoneal macrophages, attachment and invasion in channel catfish ovary (CCO) cells, in vitro stress resistance, and virulence and efficacy in channel catfish. Among the mutants, EiΔevpA, EiΔevpH, EiΔevpM, EiΔevpN, and EiΔevpO exhibited reduced replication inside peritoneal macrophages. EiΔevpM, EiΔevpN, and EiΔevpO showed significantly decreased attachment to CCO cells, while EiΔevpN and EiΔevpO also displayed reduced invasion of CCO cells (p < 0.05). Overall, T6SS mutants demonstrated enhanced resistance to oxidative and nitrosative stress in the nutrient-rich medium compared to the minimal medium. However, EiΔevpA, EiΔevpH, EiΔevpM, EiΔevpN, and EiΔevpO were susceptible to oxidative stress in both nutrient-rich and minimal medium. In fish challenges, EiΔevpD, EiΔevpE, EiΔevpG, EiΔevpJ, and EiΔevpK exhibited attenuation and provided effective protection against E. ictaluri wild-type (EiWT) infection in catfish fingerlings. However, their attenuation and protective efficacy were lower in catfish fry. These findings shed light on the role of the T6SS in E. ictaluri pathogenesis, highlighting its significance in intracellular survival, host cell attachment and invasion, stress resistance, and virulence. The attenuated T6SS mutants hold promise as potential candidates for protective immunization strategies in catfish fingerlings.
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Affiliation(s)
- Safak Kalindamar
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Ordu University, Ordu, Türkiye
| | - Hossam Abdelhamed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Adef O. Kordon
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Hasan C. Tekedar
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Lesya Pinchuk
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
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6
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Zhang LQ, Shen YL, Ye BC, Zhou Y. Acetylation of K188 and K192 inhibits the DNA-binding ability of NarL to regulate Salmonella virulence. Appl Environ Microbiol 2023; 89:e0068523. [PMID: 37732772 PMCID: PMC10617396 DOI: 10.1128/aem.00685-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/26/2023] [Indexed: 09/22/2023] Open
Abstract
Salmonella infection significantly increases nitrate levels in the intestine, immune cells, and immune organs of the host, and it can exploit nitrate as an electron acceptor to enhance its growth. In the presence of nitrate or nitrite, NarL, a regulatory protein of the Nar two-component system, is activated and regulates a number of genes involved in nitrate metabolism. However, research on NarL at the post-translational level is limited. In this study, we demonstrate that the DNA-binding sites K188 and 192 of NarL can be acetylated by bacterial metabolite acetyl phosphate and that the degree of acetylation has a considerable influence on the regulatory function of NarL. Specifically, acetylation of NarL negatively regulates the transcription of narG, narK, and napF, which affects the utilization of nitrate in Salmonella. Besides, both cell and mouse models show that acetylated K188 and K192 result in attenuated replication in RAW 264.7 cells, as well as impaired virulence in mouse model. Together, this research identifies a novel NarL acetylation mechanism that regulates Salmonella virulence, providing a new insight and target for salmonellosis treatment.IMPORTANCESalmonella is an important intracellular pathogen that can cause limited gastroenteritis and self-limiting gastroenteritis in immunocompetent humans. Nitrate, the highest oxidation state form of nitrogen, is critical in the formation of systemic infection in Salmonella. It functions as a signaling molecule that influences Salmonella chemotaxis, in addition to acting as a reduced external electron acceptor for Salmonella anaerobic respiration. NarL is an essential regulatory protein involved in nitrate metabolism in Salmonella, and comprehending its regulatory mechanism is necessary. Previous research has linked NarL phosphorylation to the formation of its dimer, which is required for NarL to perform its regulatory functions. Our research demonstrated that acetylation also affects the regulatory function of NarL. We found that acetylation affects Salmonella pathogenicity by weakening the ability of NarL to bind to the target sequence, further refining the mechanism of the anaerobic nitrate respiration pathway.
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Affiliation(s)
- Liu-Qing Zhang
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yi-Lin Shen
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Bang-Ce Ye
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Ying Zhou
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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7
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Worley MJ. Salmonella Bloodstream Infections. Trop Med Infect Dis 2023; 8:487. [PMID: 37999606 PMCID: PMC10675298 DOI: 10.3390/tropicalmed8110487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/23/2023] [Accepted: 10/24/2023] [Indexed: 11/25/2023] Open
Abstract
Salmonella is a major foodborne pathogen of both animals and humans. This bacterium is responsible for considerable morbidity and mortality world-wide. Different serovars of this genus cause diseases ranging from self-limiting gastroenteritis to a potentially fatal systemic disease known as enteric fever. Gastrointestinal infections with Salmonella are usually self-limiting and rarely require medical intervention. Bloodstream infections, on the other hand, are often fatal even with hospitalization. This review describes the routes and underlying mechanisms of the extraintestinal dissemination of Salmonella and the chronic infections that sometimes result. It includes information on the pathogenicity islands and individual virulence factors involved in systemic dissemination as well as a discussion of the host factors that mediate susceptibility. Also, the major outbreaks of invasive Salmonella disease in the tropics are described.
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Affiliation(s)
- Micah J Worley
- Department of Biology, University of Louisville, Louisville, KY 40292, USA
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8
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Petano-Duque JM, Rueda-García V, Rondón-Barragán IS. Virulence genes identification in Salmonella enterica isolates from humans, crocodiles, and poultry farms from two regions in Colombia. Vet World 2023; 16:2096-2103. [PMID: 38023281 PMCID: PMC10668553 DOI: 10.14202/vetworld.2023.2096-2103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/11/2023] [Indexed: 12/01/2023] Open
Abstract
Background and Aim Salmonella spp. is frequently found in the digestive tract of birds and reptiles and transmitted to humans through food. Salmonellosis is a public health problem because of pathogenicity variability in strains for virulence factors. This study aimed to identify the virulence genes in Salmonella isolates from humans, crocodiles, broiler cloacas, and broiler carcasses from two departments of Colombia. Materials and Methods This study was conducted on 31 Salmonella enterica strains from humans with gastroenteritis (seven), crocodiles (seven), broiler cloacas (six), and broiler carcasses (12) from Tolima and Santander departments of Colombia, belonging to 21 serotypes. All samples were tested for Salmonella spp. using culture method on selective and non-selective mediums. Extraction of genomic DNA was performed from fresh colonies, DNA quality was verified by spectrophotometry and confirmed by amplification of InvA gene using conventional polymerase chain reaction (PCR). bapA, fimA, icmF, IroB, marT, mgtC, nlpI, oafA, pagN, siiD, spvC, spvR, spvB, Stn, and vexA genes were amplified by PCR. Results The most prevalent gene was bapA (100%), followed by marT (96.77%), mgtC (93.55%), and fimA (83.87%). Likewise, IroB (70.97%), Stn (67.74%), spvR (61.29%), pagN (54.84%), icmF (54.8%), and SiiD (45.16%) were positive for more than 50% of the strains. Furthermore, none of the isolates tested positive for the vexA gene. Salmonella isolates presented 26 virulence profiles. Conclusion This study reported 14 virulence genes in Salmonella spp. isolates from humans with gastroenteritis, crocodiles, and broiler cloacas and carcasses. The distribution of virulence genes differed among sources. This study could help in decision-making by health and sanitary authorities.
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Affiliation(s)
- Julieth Michel Petano-Duque
- Poultry Research Group, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
| | - Valentina Rueda-García
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
| | - Iang Schroniltgen Rondón-Barragán
- Poultry Research Group, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
- Research Group in Immunobiology and Pathogenesis, Faculty of Veterinary Medicine and Zootechnics, University of Tolima, Santa Helena Highs, Ibagué, Tolima, Colombia
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9
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Blondel CJ, Amaya FA, Bustamante P, Santiviago CA, Pezoa D. Identification and distribution of new candidate T6SS effectors encoded in Salmonella Pathogenicity Island 6. Front Microbiol 2023; 14:1252344. [PMID: 37664116 PMCID: PMC10469887 DOI: 10.3389/fmicb.2023.1252344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 08/03/2023] [Indexed: 09/05/2023] Open
Abstract
The type VI secretion system (T6SS) is a contact-dependent contractile multiprotein apparatus widely distributed in Gram-negative bacteria. These systems can deliver different effector proteins into target bacterial and/or eukaryotic cells, contributing to the environmental fitness and virulence of many bacterial pathogens. Salmonella harbors five different T6SSs encoded in different genomic islands. The T6SS encoded in Salmonella Pathogenicity Island 6 (SPI-6) contributes to Salmonella competition with the host microbiota and its interaction with infected host cells. Despite its relevance, information regarding the total number of effector proteins encoded within SPI-6 and its distribution among different Salmonella enterica serotypes is limited. In this work, we performed bioinformatic and comparative genomics analyses of the SPI-6 T6SS gene cluster to expand our knowledge regarding the T6SS effector repertoire and the global distribution of these effectors in Salmonella. The analysis of a curated dataset of 60 Salmonella enterica genomes from the Secret6 database revealed the presence of 23 new putative T6SS effector/immunity protein (E/I) modules. These effectors were concentrated in the variable regions 1 to 3 (VR1-3) of the SPI-6 T6SS gene cluster. VR1-2 were enriched in candidate effectors with predicted peptidoglycan hydrolase activity, while VR3 was enriched in candidate effectors of the Rhs family with C-terminal extensions with predicted DNase, RNase, deaminase, or ADP-ribosyltransferase activity. A global analysis of known and candidate effector proteins in Salmonella enterica genomes from the NCBI database revealed that T6SS effector proteins are differentially distributed among Salmonella serotypes. While some effectors are present in over 200 serotypes, others are found in less than a dozen. A hierarchical clustering analysis identified Salmonella serotypes with distinct profiles of T6SS effectors and candidate effectors, highlighting the diversity of T6SS effector repertoires in Salmonella enterica. The existence of different repertoires of effector proteins suggests that different effector protein combinations may have a differential impact on the environmental fitness and pathogenic potential of these strains.
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Affiliation(s)
- Carlos J. Blondel
- Facultad de Medicina y Facultad de Ciencias de la Vida, Instituto de Ciencias Biomédicas, Universidad Andrés Bello, Santiago, Chile
| | - Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Paloma Bustamante
- Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - David Pezoa
- Núcleo de Investigaciones Aplicadas en Ciencias Veterinarias y Agronómicas, Facultad de Medicina Veterinaria y Agronomía, Universidad de Las Américas, Santiago, Chile
- Departamento de Ciencias Químicas y Biológicas, Universidad Bernardo O'Higgins, Santiago, Chile
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10
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Uzairue LI, Shittu OB, Ojo OE, Obuotor TM, Olanipekun G, Ajose T, Arogbonlo R, Medugu N, Ebruke B, Obaro SK. Antimicrobial resistance and virulence genes of invasive Salmonella enterica from children with bacteremia in north-central Nigeria. SAGE Open Med 2023; 11:20503121231175322. [PMID: 37223673 PMCID: PMC10201152 DOI: 10.1177/20503121231175322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/25/2023] [Indexed: 05/25/2023] Open
Abstract
Objectives Bacteremia due to invasive Salmonella enterica has been reported earlier in children in Nigeria. This study aimed to detect the virulence and antibiotic resistance genes of invasive Salmonella enterica from children with bacteremia in north-central Nigeria. Method From June 2015 to June 2018, 4163 blood cultures yielded 83 Salmonella isolates. This is a secondary cross-sectional analysis of the Salmonella isolates. The Salmonella enterica were isolated and identified using standard bacteriology protocol. Biochemical identifications of the Salmonella enterica were made by Phoenix MD 50 identification system. Further identification and confirmation were done with polyvalent antisera O and invA gene. Antimicrobial susceptibility testing was done following clinical and laboratory standard institute guidelines. Resistant genes and virulence genes were determined using a real-time polymerase chain reaction. Result Salmonella typhi 51 (61.4%) was the most prevalent serovar, followed by Salmonella species 13 (15.7%), choleraesuis 8 (9.6%), enteritidis 6 (7.2%), and typhimurium 5 (6.1%). Fifty-one (61.4%) of 83 Salmonella enterica were typhoidal, while 32 (38.6%) were not. Sixty-five (78.3%) of the 83 Salmonella enterica isolates were resistant to ampicillin and trimethoprim-sulfamethoxazole, followed by chloramphenicol 39 (46.7%), tetracycline 41 (41.4%), piperacillin 33 (33.9%), amoxicillin-clavulanate, and streptomycin 21 (25.3%), while cephalothin was 19 (22.9%). Thirty-nine (46.9%) of the 83 Salmonella enterica isolates were multi-drug resistant, and none were extensive drug resistant or pan-drug resistant. A blaTEM 42 (50.6%), floR 32 (38.6%), qnrA 24 (28.9%), tetB 20 (20.1%), tetA 10 (10.0%), and tetG 5 (6.0%) were the antibiotic resistance genes detected. There were perfect agreement between phenotypic and genotypic detection of antimicrobial resistance in tetracycline, ciprofloxacin, and chloramphenicol, while beta-lactam showed κ = 0.60 agreement. All of the Salmonella enterica isolates had the virulence genes invA, sopB, mgtC, and sip4D, while 33 (39.8%), 45 (51.8%), and 2 (2.4%) had ssaQ, spvC, and ljsGI-1, respectively. Conclusion Our findings showed multi-drug resistant Salmonella enterica in children with bacteremia in northern Nigeria. In addition, significant virulence and antimicrobial resistance genes were found in invasive Salmonella enterica in northern Nigeria. Thus, our study emphasizes the need to monitor antimicrobial resistance in Salmonella enterica from invasive sources in Nigeria and supports antibiotic prudence.
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Affiliation(s)
- Leonard I Uzairue
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Department of Medical Laboratory
Sciences, Federal University Oye Ekiti, Ekiti State, Nigeria
| | - Olufunke B Shittu
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Olufemi E Ojo
- Department of Veterinary Microbiology
and Parasitology, Federal University of Agriculture, Abeokuta, Nigeria
| | - Tolulope M Obuotor
- Department of Microbiology, Federal
University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Grace Olanipekun
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Theresa Ajose
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Ronke Arogbonlo
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Nubwa Medugu
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Department of Microbiology and
Parasitology, National Hospital, Abuja, FCT, Nigeria
| | - Bernard Ebruke
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
| | - Stephen K Obaro
- International Foundation Against
Infectious Disease in Nigeria, Abuja, Nigeria
- Pediatric Infectious Division, the
University of Nebraska Medical Center, Omaha, NE, USA
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11
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Zhou G, Zhao Y, Ma Q, Li Q, Wang S, Shi H. Manipulation of host immune defenses by effector proteins delivered from multiple secretion systems of Salmonella and its application in vaccine research. Front Immunol 2023; 14:1152017. [PMID: 37081875 PMCID: PMC10112668 DOI: 10.3389/fimmu.2023.1152017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/23/2023] [Indexed: 04/07/2023] Open
Abstract
Salmonella is an important zoonotic bacterial species and hazardous for the health of human beings and livestock globally. Depending on the host, Salmonella can cause diseases ranging from gastroenteritis to life-threatening systemic infection. In this review, we discuss the effector proteins used by Salmonella to evade or manipulate four different levels of host immune defenses: commensal flora, intestinal epithelial-mucosal barrier, innate and adaptive immunity. At present, Salmonella has evolved a variety of strategies against host defense mechanisms, among which various effector proteins delivered by the secretory systems play a key role. During its passage through the digestive system, Salmonella has to face the intact intestinal epithelial barrier as well as competition with commensal flora. After invasion of host cells, Salmonella manipulates inflammatory pathways, ubiquitination and autophagy processes with the help of effector proteins. Finally, Salmonella evades the adaptive immune system by interfering the migration of dendritic cells and interacting with T and B lymphocytes. In conclusion, Salmonella can manipulate multiple aspects of host defense to promote its replication in the host.
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Affiliation(s)
- Guodong Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Yuying Zhao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Qifeng Ma
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Quan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States
| | - Huoying Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University (JIRLAAPS), Yangzhou, China
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12
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Singh RP, Kumari K. Bacterial type VI secretion system (T6SS): an evolved molecular weapon with diverse functionality. Biotechnol Lett 2023; 45:309-331. [PMID: 36683130 DOI: 10.1007/s10529-023-03354-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/14/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Bacterial secretion systems are nanomolecular complexes that release a diverse set of virulence factors/or proteins into its surrounding or translocate to their target host cells. Among these systems, type VI secretion system 'T6SS' is a recently discovered molecular secretion system which is widely distributed in Gram-negative (-ve) bacteria, and shares structural similarity with the puncturing device of bacteriophages. The presence of T6SS is an advantage to many bacteria as it delivers toxins to its neighbour pathogens for competitive survival, and also translocates protein effectors to the host cells, leading to disruption of lipid membranes, cell walls, and cytoskeletons etc. Recent studies have characterized both anti-prokaryotic and anti-eukaryotic effectors, where T6SS is involved in diverse cellular functions including favouring colonization, enhancing the survival, adhesive modifications, internalization, and evasion of the immune system. With the evolution of advanced genomics and proteomics tools, there has been an increase in the number of characterized T6SS effector arsenals and also more clear information about the adaptive significance of this complex system. The functions of T6SS are generally regulated at the transcription, post-transcription and post-translational levels through diverse mechanisms. In the present review, we aimed to provide information about the distribution of T6SS in diverse bacteria, any structural similarity/or dissimilarity, effectors proteins, functional significance, and regulatory mechanisms. We also tried to provide information about the diverse roles played by T6SS in its natural environments and hosts, and further any changes in the microbiome.
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Affiliation(s)
- Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India.
| | - Kiran Kumari
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
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13
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Has EG, Akçelik N, Akçelik M. Comparative global gene expression analysis of biofilm forms of Salmonella Typhimurium ATCC 14028 and its seqA mutant. Gene X 2023; 853:147094. [PMID: 36470486 DOI: 10.1016/j.gene.2022.147094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/01/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022] Open
Abstract
In this study, comparative transcriptomic analyzes (mRNA and miRNA) were performed on the biofilm forms of S. Typhimurium ATCC 14028 wild-type strain and its seqA gene mutant in order to determine the regulation characteristics of the seqA gene in detail. The results of global gene expression analyses showed an increase in the expression level of 54 genes and a decrease in the expression level of 155 genes (p < 0.05) in the seqA mutant compared to the wild-type strain. 10 of the 48 miRNAs identified on behalf of sequence analysis are new miRNA records for Salmonella. Transcripts of 14 miRNAs differed between wild-type strain and seqA mutant (p < 0.05), of which eight were up-regulated and six were down-regulated. Bioinformatic analyzes showed that differentially expressed genes in the wild-type strain and its seqA gene mutant play a role in different metabolic processes as well as biofilm formation, pathogenicity and virulence. When the transcriptomic data were interpreted together with the findings obtained from phenotypic tests such as motility, attachment to host cells and biofilm morphotyping, it was determined that the seqA gene has a critical function especially for the adhesion and colonization stages of biofilm formation, as well as for biofilm stability. Transcriptomic data pointing out that the seqA gene is also a general positive regulator of T3SS effector proteins active in cell invasion in S. Typhimurium wild-type biofilm, proves that this gene is involved in Salmonella host cell invasion.
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Affiliation(s)
- Elif Gamze Has
- Department of Biology, Ankara University, Yenimahalle, 06100 Ankara, Turkey
| | - Nefise Akçelik
- Biotechnology Institute, Ankara University, Keçiören, 06135 Ankara, Turkey
| | - Mustafa Akçelik
- Department of Biology, Ankara University, Yenimahalle, 06100 Ankara, Turkey.
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14
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Acetylation of Cyclic AMP Receptor Protein by Acetyl Phosphate Modulates Mycobacterial Virulence. Microbiol Spectr 2023; 11:e0400222. [PMID: 36700638 PMCID: PMC9927398 DOI: 10.1128/spectrum.04002-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The success of Mycobacterium tuberculosis (Mtb) as a pathogen is partly attributed to its ability to sense and respond to dynamic host microenvironments. The cyclic AMP (cAMP) receptor protein (CRP) is closely related to the pathogenicity of Mtb and plays an important role in this process. However, the molecular mechanisms guiding the autoregulation and downstream target genes of CRP while Mtb responds to its environment are not fully understood. Here, it is demonstrated that the acetylation of conserved lysine 193 (K193) within the C-terminal DNA-binding domain of CRP reduces its DNA-binding ability and inhibits transcriptional activity. The reversible acetylation status of CRP K193 was shown to significantly affect mycobacterial growth phenotype, alter the stress response, and regulate the expression of biologically relevant genes using a CRP K193 site-specific mutation. Notably, the acetylation level of K193 decreases under CRP-activating conditions, including the presence of cAMP, low pH, high temperature, and oxidative stress, suggesting that microenvironmental signals can directly regulate CRP K193 acetylation. Both cell- and murine-based infection assays confirmed that CRP K193 is critical to the regulation of Mtb virulence. Furthermore, the acetylation of CRP K193 was shown to be dependent on the intracellular metabolic intermediate acetyl phosphate (AcP), and deacetylation was mediated by NAD+-dependent deacetylases. These findings indicate that AcP-mediated acetylation of CRP K193 decreases CRP activity and negatively regulates the pathogenicity of Mtb. We believe that the underlying mechanisms of cross talk between transcription, posttranslational modifications, and metabolites are a common regulatory mechanism for pathogenic bacteria. IMPORTANCE Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, and the ability of Mtb to survive harsh host conditions has been the subject of intensive research. As a result, we explored the molecular mechanisms guiding downstream target genes of CRP when Mtb responds to its environment. Our study makes a contribution to the literature because we describe the role of acetylated K193 in regulating its binding affinity to target DNA and influencing the virulence of mycobacteria. We discovered that mycobacteria can regulate their pathogenicity through the reversible acetylation of CRP K193 and that this reversible acetylation is mediated by AcP and a NAD+-dependent deacetylase. The regulation of CRPMtb by posttranslational modifications, at the transcriptional level, and by metabolic intermediates contribute to a better understanding of its role in the survival and pathogenicity of mycobacteria.
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15
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Song L, Wu J, Weng K, Yao F, Vongsangnak W, Zhu G, Chen G, Zhang Y, Xu Q. The salmonella effector Hcp modulates infection response, and affects salmonella adhesion and egg contamination incidences in ducks. Front Cell Infect Microbiol 2022; 12:948237. [PMID: 36262184 PMCID: PMC9575552 DOI: 10.3389/fcimb.2022.948237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022] Open
Abstract
Salmonella Entertidis (SE) often causes persistent infections and egg contamination in laying ducks. Hcp, the core structural and effector proteins of the Type VI Secretion System (T6SS) in SE, contributes to bacterial invasion, adhesion and virulence. However, little is known about the effect of Hcp on the host’s infection responses and egg contamination incidences in duck. Herein, we generated an hcp deletion mutant SE MY1△hcp and detected its ability to invade duck granulosa cells (dGCs) and contaminate eggs. In comparison with MY1-infected group, the SE adhesion decreased by 15.96% in MY1△hcp-infected dGCs, and the apoptosis in MY1△hcp-infected dGCs decreased by 26.58% and 30.99% at 3 and 6 hours postinfection, respectively. However, the expression levels of immunogenic genes TLR4, NOD1, TNFα, IL-1β and proinflammatory cytokines IL-6, IL-1β, TNF-α release were markedly lower in the dGCs inoculated with MY1△hcp than that of the wild type. Besides, the laying ducks were challenged with MY1 or MY1△hcp in vivo, respectively. The lower egg production and higher egg contamination were observed in MY1-infected ducks in comparison with MY1△hcp-infected birds. Furthermore, the host’s infection response of differentially abundant proteins (DAPs) to Salmonella effector Hcp was identified using quantitative proteomics. A total of 164 DAPs were identified between the MY1- and MY1△hcp-infected cells, which were mainly engaged in the immune, hormone synthesis, cell proliferation and cell apoptotic process. Among them, STAT3, AKT1, MAPK9, MAPK14, and CREBBP were the center of the regulatory network, which might serve as key host response regulators to bacterial Hcp. In conclusion, we demonstrated that effector Hcp contributed to not only SE invasion, induction of dGCs apoptosis, and trigger of immune responses, but also enhanced contamination incidences. Also, the STAT3, AKT1, MAPK9, MAPK14, and CREBBP were identified as host’s infection response regulators of bacterial Hcp in duck. Overall, these results not only offered a novel evidence of SE ovarian transmission but also identified some promising candidate regulators during SE infection.
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Affiliation(s)
- Lina Song
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Jia Wu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Kaiqi Weng
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Fenghua Yao
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Wanwipa Vongsangnak
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Guoqiang Zhu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Guohong Chen
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Yu Zhang
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
- *Correspondence: Yu Zhang,
| | - Qi Xu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
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16
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Lorente Cobo N, Sibinelli-Sousa S, Biboy J, Vollmer W, Bayer-Santos E, Prehna G. Molecular characterization of the type VI secretion system effector Tlde1a reveals a structurally altered LD-transpeptidase fold. J Biol Chem 2022; 298:102556. [PMID: 36183829 PMCID: PMC9638812 DOI: 10.1016/j.jbc.2022.102556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 12/01/2022] Open
Abstract
The type VI secretion system (T6SS) is a molecular machine that Gram-negative bacteria have adapted for multiple functions, including interbacterial competition. Bacteria use the T6SS to deliver protein effectors into adjacent cells to kill rivals and establish niche dominance. Central to T6SS-mediated bacterial competition is an arms race to acquire diverse effectors to attack and neutralize target cells. The peptidoglycan has a central role in bacterial cell physiology, and effectors that biochemically modify peptidoglycan structure effectively induce cell death. One such T6SS effector is Tlde1a from Salmonella Typhimurium. Tlde1a functions as an LD-carboxypeptidase to cleave tetrapeptide stems and as an LD-transpeptidase to exchange the terminal D-alanine of a tetrapeptide stem with a noncanonical D-amino acid. To understand how Tlde1a exhibits toxicity at the molecular level, we determined the X-ray crystal structure of Tlde1a alone and in complex with D-amino acids. Our structural data revealed that Tlde1a possesses a unique LD-transpeptidase fold consisting of a dual pocket active site with a capping subdomain. This includes an exchange pocket to bind a D-amino acid for exchange and a catalytic pocket to position the D-alanine of a tetrapeptide stem for cleavage. Our toxicity assays in Escherichia coli and in vitro peptidoglycan biochemical assays with Tlde1a variants correlate Tlde1a molecular features directly to its biochemical functions. We observe that the LD-carboxypeptidase and LD-transpeptidase activities of Tlde1a are both structurally and functionally linked. Overall, our data highlight how an LD-transpeptidase fold has been structurally altered to create a toxic effector in the T6SS arms race.
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Affiliation(s)
- Neil Lorente Cobo
- Department of Microbiology, University of Manitoba, Winnipeg, Canada
| | - Stephanie Sibinelli-Sousa
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Ethel Bayer-Santos
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, São Paulo, Brazil
| | - Gerd Prehna
- Department of Microbiology, University of Manitoba, Winnipeg, Canada.
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17
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Amaya FA, Blondel CJ, Barros-Infante MF, Rivera D, Moreno-Switt AI, Santiviago CA, Pezoa D. Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Salmonella Dublin. Front Microbiol 2022; 13:811932. [PMID: 35222335 PMCID: PMC8867033 DOI: 10.3389/fmicb.2022.811932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/04/2022] [Indexed: 12/12/2022] Open
Abstract
The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells via a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In Salmonella, five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes. Salmonella enterica serotype Dublin (S. Dublin) is a cattle-adapted pathogen that harbors both T6SSSPI-6 and T6SSSPI-19. Interestingly, while both systems have been linked to virulence and host colonization in S. Dublin, an antibacterial activity has not been detected for T6SSSPI-6 in this serotype. In addition, there is limited information regarding the repertoire of effector proteins encoded within T6SSSPI-6 and T6SSSPI-19 gene clusters in S. Dublin. In the present study, we demonstrate that T6SSSPI-6 and T6SSSPI-19 of S. Dublin CT_02021853 contribute to interbacterial competition. Bioinformatic and comparative genomic analyses allowed us to identify genes encoding three candidate antibacterial effectors located within SPI-6 and two candidate effectors located within SPI-19. Each antibacterial effector gene is located upstream of a gene encoding a hypothetic immunity protein, thus conforming an effector/immunity (E/I) module. Of note, the genes encoding these effectors and immunity proteins are widely distributed in Salmonella genomes, suggesting a relevant role in interbacterial competition and virulence. Finally, we demonstrate that E/I modules SED_RS01930/SED_RS01935 (encoded in SPI-6), SED_RS06235/SED_RS06230, and SED_RS06335/SED_RS06340 (both encoded in SPI-19) contribute to interbacterial competition in S. Dublin CT_02021853.
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Affiliation(s)
- Fernando A. Amaya
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos J. Blondel
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | | | - Dácil Rivera
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Andrea I. Moreno-Switt
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Millennium Initiative on Collaborative Research on Bacterial Resistance (MICROB-R), Santiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
| | - David Pezoa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- *Correspondence: Carlos A. Santiviago, David Pezoa,
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18
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Ray S, Pandey NK, Kushwaha GS, Das S, Ganguly AK, Vashi N, Kumar D, Suar M, Bhavesh NS. Structural investigation on SPI-6 associated Salmonella Typhimurium VirG-like stress protein that promotes pathogen survival in macrophages. Protein Sci 2022; 31:835-849. [PMID: 34997791 DOI: 10.1002/pro.4272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 11/10/2022]
Abstract
Enteric microbial pathogenesis, remarkably a complex process, is achieved by virulence factors encoded by genes located within regions of the bacterial genome termed pathogenicity islands. Salmonella pathogenicity islands (SPI) encodes proteins, that are essential virulence determinants for pathogen colonization and virulence. In addition to the well-characterized SPI-1 and SPI-2 proteins, which are required for bacterial invasion and intracellular replication, respectively, SPI-6 (formerly known as Salmonella enterica centisome 7 island; SCI) encoding proteins are also known to play pivotal role in Salmonella pathogenesis. However, the underlying molecular mechanism of these proteins remained elusive. To gain molecular insights into SPI-6 associated proteins, in this study, a SPI-6 Salmonella Typhimurium VirG-like protein (STV) is characterized using interdisciplinary experimental approaches including X-ray crystallography, NMR spectroscopy, infection assays, and mice model. The high-resolution crystal structure, determined by the single-wavelength anomalous dispersion (SAD) method, reveals that STV belongs to the LTxxQ motif family. Solution-state NMR spectroscopy studies reveal that STV form a dimer involving interconnected helices. Interestingly, functional studies shows that STV influence pathogen persistence inside macrophages in vitro at later stages of infection. Altogether, our findings suggest that STV, a member of the LTxxQ stress protein family, modulates bacterial survival mechanism in macrophages through SPI-1 and SPI-2 genes, respectively. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Shilpa Ray
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Nishant Kumar Pandey
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India.,Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Gajraj Singh Kushwaha
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India.,KIIT-Technology Business Incubator, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Susmita Das
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Akshay Kumar Ganguly
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Nimi Vashi
- Cellular Immunology group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Dhiraj Kumar
- Cellular Immunology group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Mrutyunjay Suar
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India.,KIIT-Technology Business Incubator, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Neel Sarovar Bhavesh
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
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19
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Abstract
The two-component system PhoP/PhoQ is essential for Salmonella enterica serovar Typhimurium virulence. Here, we report that PhoP is methylated extensively. Two consecutive glutamate (E) and aspartate (D)/E residues, i.e., E8/D9 and E107/E108, and arginine (R) 112 can be methylated. Individual mutation of these above-mentioned residues caused impaired phosphorylation and dimerization or DNA-binding ability of PhoP to a different extent and led to attenuated bacterial virulence. With the help of specific antibodies recognizing methylated E8 and monomethylated R112, we found that the methylation levels of E8 or R112 decreased dramatically when bacteria encountered low magnesium, acidic pH, or phagocytosis by macrophages, under which PhoP can be activated. Furthermore, CheR, a bacterial chemotaxis methyltransferase, was identified to methylate R112. Overexpression of cheR decreased PhoP activity but increased PhoP stability. Together, the current study reveals that methylation plays an important role in regulating PhoP activities in response to environmental cues and, consequently, modulates Salmonella virulence.
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20
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Kamruzzaman M, Wu AY, Iredell JR. Biological Functions of Type II Toxin-Antitoxin Systems in Bacteria. Microorganisms 2021; 9:microorganisms9061276. [PMID: 34208120 PMCID: PMC8230891 DOI: 10.3390/microorganisms9061276] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/14/2022] Open
Abstract
After the first discovery in the 1980s in F-plasmids as a plasmid maintenance system, a myriad of toxin-antitoxin (TA) systems has been identified in bacterial chromosomes and mobile genetic elements (MGEs), including plasmids and bacteriophages. TA systems are small genetic modules that encode a toxin and its antidote and can be divided into seven types based on the nature of the antitoxin molecules and their mechanism of action to neutralise toxins. Among them, type II TA systems are widely distributed in chromosomes and plasmids and the best studied so far. Maintaining genetic material may be the major function of type II TA systems associated with MGEs, but the chromosomal TA systems contribute largely to functions associated with bacterial physiology, including the management of different stresses, virulence and pathogenesis. Due to growing interest in TA research, extensive work has been conducted in recent decades to better understand the physiological roles of these chromosomally encoded modules. However, there are still controversies about some of the functions associated with different TA systems. This review will discuss the most current findings and the bona fide functions of bacterial type II TA systems.
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Affiliation(s)
- Muhammad Kamruzzaman
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia;
- Correspondence: (M.K.); (J.R.I.)
| | - Alma Y. Wu
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia;
| | - Jonathan R. Iredell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia;
- Westmead Hospital, Westmead, NSW 2145, Australia
- Correspondence: (M.K.); (J.R.I.)
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21
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Wang P, Dong JF, Li RQ, Li L, Zou QH. Roles of the Hcp family proteins in the pathogenicity of Salmonella typhimurium 14028s. Virulence 2020; 11:1716-1726. [PMID: 33300449 PMCID: PMC7733977 DOI: 10.1080/21505594.2020.1854538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The type VI secretion system (T6SS) is a new secretion system that is widely distributed among Gram-negative bacteria. The core component hemolysin-coregulated protein (Hcp) can be used as both its structural protein and secretory protein or chaperone protein. Studies on Hcp are important to elucidate the overall virulence mechanism of T6SS. Salmonella typhimurium is an important foodborne pathogen. There are three copies of hcp genes identified in S. Typhimurium 14028s. This study aimed to characterize the functions of the three Hcp family proteins and to elucidate the interactions among them. The hcp gene deletion mutants were constructed by λ Red-based recombination system. Effects of hcp mutation on the pathogenicity of 14028s were studied by bacterial competition assays, Dictyostelium discoideum assays and mouse model. The three Hcp family proteins were found to play different roles. Hcp1 can affect the transcription of rpoS and type 2 flagellar gene and influence the motility of 14028s. It is also involved in the intracellular survival of 14028s in Dictyostelium discoideum; Hcp2 is involved in the early proliferative capacity of 14028s in mice and can prevent its excessive proliferation; Hcp3 did not show direct functions in these assays. Hcp1 can interact with Hcp2 and Hcp3. Deletion of one hcp gene can result in a transcription level variation in the other two hcp genes. Our findings elucidated the functions of the three Hcp family proteins in S.Typhimurium and illustrated that there are interactions between different Hcp proteins. This study will be helpful to fully understand how T6SS actions in an organism.
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Affiliation(s)
- Ping Wang
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Jun-Fang Dong
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Ren-Qing Li
- Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine , Beijing, China
| | - Lei Li
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China.,The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology , Beijing, China
| | - Qing-Hua Zou
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
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22
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Zhou G, Liang H, Gu Y, Ju C, He L, Guo P, Shao Z, Zhang J, Zhang M. Comparative genomics of Helicobacter pullorum from different countries. Gut Pathog 2020; 12:56. [PMID: 33303031 PMCID: PMC7727170 DOI: 10.1186/s13099-020-00394-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 11/24/2020] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Helicobacter pullorum commonly colonized in the gastrointestinal tract of poultry and caused gastroenteritis. This bacterium could be transmitted to humans through contaminated food and caused colitis and hepatitis. Currently, the genetic characteristics of the H. pullorum were not recognized enough. In this study, the genomes of 23 H. pullorum strains from different counties were comparatively analyzed. Among them, H. pullorum 2013BJHL was the first isolated and reported in China. RESULTS The genomes of the studied strains were estimated to vary from 1.55 to 2.03 Mb, with a GC content of ~ 34%. 4064 pan genes and 1267 core genes were obtained from the core-pan genome analysis using the Roary pipeline. Core genome SNPs (cg-SNPs) were obtained using Snippy4 software. Two groups were identified with the phylogenetic analysis based on the cg-SNPs. Some adhesion-related, immune regulation, motility-related, antiphagocytosis-related, toxin-related and quorum sensing related genes were identified as virulence factors. APH(3')-IIIa, APH(2'')-If, and AAC(6')-Ie-APH(2'')-Ia were identified as antibiotic resistance genes among the H. pullorum genomes. cat, SAT-4 and tetO genes were only identified in 2013BJHL, and tet(C) was identified in MIT98-5489. MIC determination revealed that the 2013BJHL showed acquired resistance to ciprofloxacin, nalidixic acid, tetracycline, gentamicin, streptomycin and erythromycin, only sensitive to ampicillin. The antibiotic resistance genetic determinants on the 2013BJHL genome correlate well with observed antimicrobial susceptibility patterns. Two types of VI secretion system (T6SS) were identified in 52.2% (12/23) the studied strains. CONCLUSION In this study, we obtained the genetic characteristics of H. pullorum from different sources in the world. The comprehensive genetic characteristics of H. pullorum were first described. H. pullorum showed highly genetic diversity and two sub-types of T6SSs were first identified in H. pullorum. 2013BJHL was found to be multidrug resistant as it was resistant to at least three different antibiotic classes.
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Affiliation(s)
- Guilan Zhou
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Hao Liang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China.,School of Public Health, Shandong University, Shandong, China
| | - Yixin Gu
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Changyan Ju
- Nanshan Center for Disease Control and Prevention, Shenzhen, China
| | - Lihua He
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Pengbo Guo
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Zhujun Shao
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Jianzhong Zhang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China
| | - Maojun Zhang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Rd155, Changbailu, Changping, Beijing, 102206, People's Republic of China.
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23
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Xie Z, Zhang Y, Huang X. Evidence and speculation: the response of Salmonella confronted by autophagy in macrophages. Future Microbiol 2020; 15:1277-1286. [PMID: 33026883 DOI: 10.2217/fmb-2020-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from self-limited gastroenteritis to typhoid fever. Macrophages are immune cells that engulf and restrict Salmonella. These cells will carry Salmonella into the circulatory system and provoke a systemic infection. Therefore, the interaction between macrophages and intracellular Salmonella is vital for its pathogenicity. As one of the immune responses of macrophages, autophagy, along with the fusion of autophagosomes with lysosomes, occupies an important position in eliminating Salmonella. However, Salmonella that can overcome cellular defensive responses and infect neighboring cells must derive strategies to escape autophagy. This review introduces novel findings on Salmonella and macrophage autophagy as a mechanism against infection and explores the strategies used by Salmonella to escape autophagy.
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Affiliation(s)
- Zhongyi Xie
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.,International Genome Center, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ying Zhang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Xinxiang Huang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
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24
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The SPI-19 encoded T6SS is required for Salmonella Pullorum survival within avian macrophages and initial colonization in chicken dependent on inhibition of host immune response. Vet Microbiol 2020; 250:108867. [PMID: 33010573 DOI: 10.1016/j.vetmic.2020.108867] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022]
Abstract
SalmonellaPathogenicity Island 19 (SPI-19) encoded type VI secretion system (T6SS) is a virulence factor present in few serotypes of S. enterica, including S. Dublin, S. Gallinarum and S. Pullorum. Comparative genomic sequence analysis revealed that the gene clusters of SPI-19 showed high homology to T6SS2 locus from avian pathogenic Escherichia coli, implying the similar T6SS locus is potentially related to the host adaption of both pathogens. Deletion of SPI-19 in S. Pullorum caused the dramatically decreased invasion into chicken LMH epithelial cells and HD-11 macrophages, and affected survival of Salmonella within both cells. In addition, deletion of SPI-19 caused the decreased colonization of S. Pullorum in chicken liver, spleen, ileum, and cecum at the initial infection stage, and induced rapid bacterial clearance. However, the SPI-19/T6SS had no effect on bacterial killing activity and induction of cytotoxicity to HD-11 macrophages. Further analysis demonstrated SPI-19/T6SS was involved in mediating the inhibition of host Th1 and Th2 immune responses, resulting in persistent colonization of S. Pullorum in hosts.
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25
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Bao H, Wang S, Zhao JH, Liu SL. Salmonella secretion systems: Differential roles in pathogen-host interactions. Microbiol Res 2020; 241:126591. [PMID: 32932132 DOI: 10.1016/j.micres.2020.126591] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/24/2020] [Accepted: 08/29/2020] [Indexed: 12/26/2022]
Abstract
The bacterial genus Salmonella includes a large group of food-borne pathogens that cause a variety of gastrointestinal or systemic diseases in hosts. Salmonella use several secretion devices to inject various effectors targeting eukaryotic hosts, or bacteria. In the past few years, considerable progress has been made towards understanding the structural features and molecular mechanisms of the secretion systems of Salmonella, particularly regarding their roles in host-pathogen interactions. In this review, we summarize the current advances about the main characteristics of the Salmonella secretion systems. Clarifying the roles of the secretion systems in the process of infecting various hosts will broaden our understanding of the importance of microbial interactions in maintaining human health and will provide information for developing novel therapeutic approaches.
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Affiliation(s)
- Hongxia Bao
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China.
| | - Shuang Wang
- Department of Biopharmaceutical Sciences (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Jian-Hua Zhao
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Shu-Lin Liu
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada.
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26
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Guérin F, Lallement C, Goudergues B, Isnard C, Sanguinetti M, Cacaci M, Torelli R, Cattoir V, Giard JC. Landscape of in vivo Fitness-Associated Genes of Enterobacter cloacae Complex. Front Microbiol 2020; 11:1609. [PMID: 32754144 PMCID: PMC7365913 DOI: 10.3389/fmicb.2020.01609] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/19/2020] [Indexed: 11/13/2022] Open
Abstract
Species of the Enterobacter cloacae complex (ECC) represent an increasing cause of hospital-acquired infections and commonly exhibit multiple antibiotic resistances. In order to identify genes that may play a role in its ability to colonize the host, we used the transposon-sequencing (Tn-seq) approach. To this end, a high-density random transposon insertion library was obtained from E. cloacae subsp. cloacae ATCC 13047, which was used to analyze the fitness of ca. 300,000 mutants in Galleria mellonella colonization model. Following massively parallel sequencing, we identified 624 genes that seemed essential for the optimal growth and/or the fitness within the host. Moreover, 63 genes where mutations resulted in positive selection were found, while 576 genes potentially involved in the in vivo fitness were observed. These findings pointed out the role of some transcriptional regulators, type VI secretion system, and surface-associated proteins in the in vivo fitness of E. cloacae ATCC 13047. We then selected eight genes based on their high positive or negative fold changes (FCs) and tested the corresponding deletion mutants for their virulence and ability to cope with stresses. Thereby, we showed that ECL_02247 (encoding the NAD-dependent epimerase/dehydratase) and ECL_04444 (coding for a surface antigen-like protein) may correspond to new virulence factors, and that the regulator ECL_00056 was involved in in vivo fitness. In addition, bacterial cells lacking the flagellum-specific ATP synthase FliI (ECL_03223) and the hypothetical protein ECL_01421 were affected for mobility and resistance to H2O2, respectively. All these results yield valuable information regarding genes important for infection process and stress response of E. cloacae ATCC 13047 and participate to a better understanding of the opportunistic traits in this bacterial pathogen.
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Affiliation(s)
- François Guérin
- Université de Caen Normandie, EA4655 U2RM (Équipe «Antibio-Résistance»), Caen, France.,CHU de Caen, Service de Microbiologie, Caen, France
| | - Claire Lallement
- Université de Caen Normandie, EA4655 U2RM (Équipe «Antibio-Résistance»), Caen, France
| | - Benoit Goudergues
- Université de Caen Normandie, EA4655 U2RM (Équipe «Antibio-Résistance»), Caen, France
| | - Christophe Isnard
- Université de Caen Normandie, EA4655 U2RM (Équipe «Antibio-Résistance»), Caen, France.,CHU de Caen, Service de Microbiologie, Caen, France
| | - Maurizio Sanguinetti
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Rome, Italy.,Dipartimento di Scienze di Laboratorio e Infettivologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Margherita Cacaci
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Rome, Italy.,Dipartimento di Scienze di Laboratorio e Infettivologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Riccardo Torelli
- Institute of Microbiology, Catholic University of the Sacred Heart, Rome, Italy
| | - Vincent Cattoir
- Rennes University Hospital, Department of Clinical Microbiology, Rennes, France.,Inserm U1230, University of Rennes 1, Rennes, France
| | - Jean-Christophe Giard
- Université de Caen Normandie, EA4655 U2RM (Équipe «Antibio-Résistance»), Caen, France
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27
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A Family of T6SS Antibacterial Effectors Related to l,d-Transpeptidases Targets the Peptidoglycan. Cell Rep 2020; 31:107813. [DOI: 10.1016/j.celrep.2020.107813] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/20/2020] [Accepted: 06/03/2020] [Indexed: 12/17/2022] Open
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28
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Wang M, Qazi IH, Wang L, Zhou G, Han H. Salmonella Virulence and Immune Escape. Microorganisms 2020; 8:microorganisms8030407. [PMID: 32183199 PMCID: PMC7143636 DOI: 10.3390/microorganisms8030407] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023] Open
Abstract
Salmonella genus represents the most common foodborne pathogens causing morbidity, mortality, and burden of disease in all regions of the world. The introduction of antimicrobial agents and Salmonella-specific phages has been considered as an effective intervention strategy to reduce Salmonella contamination. However, data from the United States, European countries, and low- and middle-income countries indicate that Salmonella cases are still a commonly encountered cause of bacterial foodborne diseases globally. The control programs have not been successful and even led to the emergence of some multidrug-resistant Salmonella strains. It is known that the host immune system is able to effectively prevent microbial invasion and eliminate microorganisms. However, Salmonella has evolved mechanisms of resisting host physical barriers and inhibiting subsequent activation of immune response through their virulence factors. There has been a high interest in understanding how Salmonella interacts with the host. Therefore, in the present review, we characterize the functions of Salmonella virulence genes and particularly focus on the mechanisms of immune escape in light of evidence from the emerging mainstream literature.
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Affiliation(s)
- Mengyao Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Izhar Hyder Qazi
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Department of Veterinary Anatomy and Histology, Shaheed Benazir Bhutto University of Veterinary and Animal Sciences, Sakrand 67210, Pakistan
| | - Linli Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Guangbin Zhou
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Correspondence: (H.H.); (G.Z.)
| | - Hongbing Han
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- Correspondence: (H.H.); (G.Z.)
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29
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Stårsta M, Hammarlöf DL, Wäneskog M, Schlegel S, Xu F, Heden Gynnå A, Borg M, Herschend S, Koskiniemi S. RHS-elements function as type II toxin-antitoxin modules that regulate intra-macrophage replication of Salmonella Typhimurium. PLoS Genet 2020; 16:e1008607. [PMID: 32053596 PMCID: PMC7043789 DOI: 10.1371/journal.pgen.1008607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 02/26/2020] [Accepted: 01/12/2020] [Indexed: 11/19/2022] Open
Abstract
RHS elements are components of conserved toxin-delivery systems, wide-spread within the bacterial kingdom and some of the most positively selected genes known. However, very little is known about how Rhs toxins affect bacterial biology. Salmonella Typhimurium contains a full-length rhs gene and an adjacent orphan rhs gene, which lacks the conserved delivery part of the Rhs protein. Here we show that, in addition to the conventional delivery, Rhs toxin-antitoxin pairs encode for functional type-II toxin-antitoxin (TA) loci that regulate S. Typhimurium proliferation within macrophages. Mutant S. Typhimurium cells lacking both Rhs toxins proliferate 2-times better within macrophages, mainly because of an increased growth rate. Thus, in addition to providing strong positive selection for the rhs loci under conditions when there is little or no toxin delivery, internal expression of the toxin-antitoxin system regulates growth in the stressful environment found inside macrophages. Bacteria that reside and multiply inside of phagocytic cells are hard to treat with common antibiotics, partly because subpopulations of bacteria are non-growing. Very little is known about how bacteria regulate their growth in the phagocytic vesicle. We show that RHS elements, previously known to function as mobilizable toxins that inhibit growth of neighboring bacteria, also function as internally expressed toxin-antitoxin systems that regulate Salmonella Typhimurium growth in macrophages. RHS elements were discovered more than 30 years ago, but their role in biology has long remained unclear even though they are some of the most positively selected genes known. Our results suggest an explanation to why rhs genes are under such strong positive selection in addition to suggesting a novel function for these toxins in regulating bacterial growth.
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Affiliation(s)
- Magnus Stårsta
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Disa L. Hammarlöf
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Marcus Wäneskog
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Susan Schlegel
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Feifei Xu
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Arvid Heden Gynnå
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Malin Borg
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sten Herschend
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
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30
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Song X, Zhang H, Liu X, Yuan J, Wang P, Lv R, Yang B, Huang D, Jiang L. The putative transcriptional regulator STM14_3563 facilitates Salmonella Typhimurium pathogenicity by activating virulence-related genes. Int Microbiol 2019; 23:381-390. [PMID: 31832871 DOI: 10.1007/s10123-019-00110-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/24/2019] [Accepted: 11/28/2019] [Indexed: 11/30/2022]
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important gram-negative intracellular pathogen that infects humans and animals. More than 50 putative regulatory proteins have been identified in the S. Typhimurium genome, but few have been clearly defined. In this study, the physiological function and regulatory role of STM14_3563, which encodes a ParD family putative transcriptional regulator in S. Typhimurium, were investigated. Macrophage replication assays and mice experiments revealed that S. Typhimurium showed reduced growth in murine macrophages and attenuated virulence in mice owing to deletion of STM14_3563 gene. RNA sequencing (RNA-Seq) data showed that STM14_3563 exerts wide-ranging effects on gene expression in S. Typhimurium. STM14_3563 activates the expression of several genes encoded in Salmonella pathogenicity island (SPI)-6, SPI-12, and SPI-13, which are required for intracellular replication of S. Typhimurium. Additionally, the global transcriptional regulator Fis was found to directly activate STM14_3563 expression by binding to the STM14_3563 promoter. These results indicate that STM14_3563 is involved in the regulation of a variety of virulence-related genes in S. Typhimurium that contribute to its growth in macrophages and virulence in mice.
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Affiliation(s)
- Xiaorui Song
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China.,College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Huan Zhang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China.,College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xiaoqian Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China
| | - Jian Yuan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China
| | - Peisheng Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China.,College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Runxia Lv
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China
| | - Bin Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China
| | - Di Huang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China.,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China
| | - Lingyan Jiang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, 300457, China. .,The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, 300071, China. .,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, 300457, China.
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31
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The Ferric Uptake Regulator Represses Type VI Secretion System Function by Binding Directly to the clpV Promoter in Salmonella enterica Serovar Typhimurium. Infect Immun 2019; 87:IAI.00562-19. [PMID: 31383745 DOI: 10.1128/iai.00562-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022] Open
Abstract
Type VI secretion systems (T6SSs) are highly conserved and complex protein secretion systems that deliver effector proteins into eukaryotic hosts or other bacteria. T6SSs are regulated precisely by a variety of regulatory systems, which enables bacteria to adapt to varied environments. A T6SS within Salmonella pathogenicity island 6 (SPI-6) is activated during infection, and it contributes to the pathogenesis, as well as interbacterial competition, of Salmonella enterica serovar Typhimurium (S. Typhimurium). However, the regulation of the SPI-6 T6SS in S. Typhimurium is not well understood. In this study, we found that the SPI-6 T6SS core gene clpV was significantly upregulated in response to the iron-depleted condition and during infection. The global ferric uptake regulator (Fur) was shown to repress the clpV expression in the iron-replete medium. Moreover, electrophoretic mobility shift and DNase I footprinting assays revealed that Fur binds directly to the clpV promoter region at multiple sites spanning the transcriptional start site. We also observed that the relieving of Fur-mediated repression on clpV contributed to the interbacterial competition activity and pathogenicity of S. Typhimurium. These findings provide insights into the direct regulation of Fur in the expression and functional activity of SPI-6 T6SS in S. Typhimurium and thus help to elucidate the mechanisms of bacterial adaptability and virulence.
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32
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Song X, Zhang H, Ma S, Song Y, Lv R, Liu X, Yang B, Huang D, Liu B, Jiang L. Transcriptome analysis of virulence gene regulation by the ATP-dependent Lon protease in Salmonella Typhimurium. Future Microbiol 2019; 14:1109-1122. [PMID: 31370702 DOI: 10.2217/fmb-2019-0118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Aim: Determination of the virulence regulatory network controlled by the ATP-dependent Lon protease in Salmonella enterica serovar Typhimurium. Materials & methods: The effect of Lon on S. Typhimurium virulence genes expression was investigated by RNA sequencing, and virulence-associated phenotypes between the wild-type and lon mutant were compared. Results: SPI-1, SPI-4, SPI-9 and flagellar genes were activated, while SPI-2 genes were repressed in the lon mutant. Accordingly, the lon mutant exhibited increased adhesion to and invasion of epithelial cells, increased motility and decreased replication in macrophages. The activation of SPI-2 genes by Lon partially accounts for the replication defect of the mutant. Conclusion: A wide range of virulence regulatory functions are governed by Lon in S. enterica ser. Typhimurium.
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Affiliation(s)
- Xiaorui Song
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China.,College of Life Sciences, Nankai University, Tianjin, 300071, PR China
| | - Huan Zhang
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China.,College of Life Sciences, Nankai University, Tianjin, 300071, PR China
| | - Shuangshuang Ma
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Yajun Song
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Runxia Lv
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Xiaoqian Liu
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Bin Yang
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Di Huang
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Bin Liu
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
| | - Lingyan Jiang
- TEDA Institute of Biological Sciences & Biotechnology, Nankai University, TEDA, Tianjin 300457, PR China.,The Key Laboratory of Molecular Microbiology & Technology, Ministry of Education, Tianjin 300071, PR China.,Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300457, PR China
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33
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The type VI secretion system protein AsaA in Acinetobacter baumannii is a periplasmic protein physically interacting with TssM and required for T6SS assembly. Sci Rep 2019; 9:9438. [PMID: 31263148 PMCID: PMC6602968 DOI: 10.1038/s41598-019-45875-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/13/2019] [Indexed: 11/11/2022] Open
Abstract
Type VI secretion system (T6SS) is described as a macromolecular secretion machine that is utilized for bacterial competition. The gene clusters encoding T6SS are composed of core tss genes and tag genes. However, the clusters differ greatly in different pathogens due to the great changes accumulated during the long-term evolution. In this work, we identified a novel hypothetical periplasmic protein designated as AsaA which is encoded by the first gene of the T6SS cluster in the genus Acinetobacter. By constructing asaA mutant, we delineated its relative contributions to bacterial competition and secretion of T6SS effector Hcp. Subsequently, we studied the localization of AsaA and potential proteins that may have interactions with AsaA. Our results showed that AsaA in Acinetobacter baumannii (A. baumannii) localized in the bacterial periplasmic space. Results based on bacterial two-hybrid system and protein pull-down assays indicated that it was most likely to affect the assembly or stability of T6SS by interacting with the T6SS core protein TssM. Collectively, our findings of AsaA is most likely a key step in understanding of the T6SS functions in A. baumannii.
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34
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Chen C, Yang X, Shen X. Confirmed and Potential Roles of Bacterial T6SSs in the Intestinal Ecosystem. Front Microbiol 2019; 10:1484. [PMID: 31316495 PMCID: PMC6611333 DOI: 10.3389/fmicb.2019.01484] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 06/14/2019] [Indexed: 12/25/2022] Open
Abstract
The contact-dependent type VI secretion system (T6SS) in diverse microbes plays crucial roles in both inter-bacterial and bacteria-host interactions. As numerous microorganisms inhabit the intestinal ecosystem at a high density, it is necessary to consider the functions of T6SS in intestinal bacteria. In this mini-review, we discuss T6SS-dependent functions in intestinal microbes, including commensal microbes and enteric pathogens, and list experimentally verified species of intestinal bacteria containing T6SS clusters. Several seminal studies have shown that T6SS plays crucial antibacterial roles in colonization resistance, niche occupancy, activation of host innate immune responses, and modulation of host intestinal mechanics. Some potential roles of T6SS in the intestinal ecosystem, such as targeting of single cell eukaryotic competitors, competition for micronutrients, and stress resistance are also discussed. Considering the distinct activities of T6SS in diverse bacteria residing in the intestine, we suggest that T6SS research in intestinal microbes may be beneficial for the future development of new medicines and clinical treatments.
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Affiliation(s)
- Can Chen
- Institute of Food and Drug Inspection, College of Life Science and Agronomy, Zhoukou Normal University, Zhoukou, China
| | - Xiaobing Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, China
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35
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Bao H, Zhao JH, Zhu S, Wang S, Zhang J, Wang XY, Hua B, Liu C, Liu H, Liu SL. Genetic diversity and evolutionary features of type VI secretion systems in Salmonella. Future Microbiol 2019; 14:139-154. [PMID: 30672329 DOI: 10.2217/fmb-2018-0260] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM Type VI secretion systems (T6SS) play key roles in bacterial pathogenesis, but their evolutionary features remain largely unclear. In this study, we conducted systematic comparisons among the documented T6SSs in Salmonella and determined their structural diversity, phylogenetic distribution and lineage-specific properties. MATERIALS & METHODS We screened 295 Salmonella genomes for 13 T6SS core components by hidden Markov models and identified 363 T6SS clusters covering types i1, i2, i3 and i4a. RESULTS Type i3 and i4a T6SSs were restricted to Salmonella enterica subspecies enterica and Salmonella bongori, respectively. whereas type i2 T6SSs were conserved between S. enterica subspecies, arizonae and diarizonae. S. enterica subspecies salamae, indica and houtenae harbored only type i1 T6SSs, which had wide distribution and high sequence diversity. CONCLUSION The diverse Salmonella T6SSs have undergone purifying selection pressures during the bacterial evolution and may be involved in host adaptation.
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Affiliation(s)
- Hongxia Bao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Jian-Hua Zhao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Songling Zhu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shuang Wang
- Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, Harbin, PR China
| | - Jianjuan Zhang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Xiao-Yu Wang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Bing Hua
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Chang Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Huidi Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shu-Lin Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China.,Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, T2N 1N4, Canada
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36
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Schroll C, Huang K, Ahmed S, Kristensen BM, Pors SE, Jelsbak L, Lemire S, Thomsen LE, Christensen JP, Jensen PR, Olsen JE. The SPI-19 encoded type-six secretion-systems (T6SS) of Salmonella enterica serovars Gallinarum and Dublin play different roles during infection. Vet Microbiol 2019; 230:23-31. [PMID: 30827393 DOI: 10.1016/j.vetmic.2019.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/05/2019] [Accepted: 01/06/2019] [Indexed: 12/19/2022]
Abstract
Salmonella Pathogenicity Islands 19 (SPI19) encodes a type VI secretion system (T6SS). SPI19 is only present in few serovars of S. enterica, including the host-adapted serovar S. Dublin and the host-specific serovar S. Gallinarum. The role of the SPI19 encoded T6SS in virulence in these serovar is not fully understood. Here we show that during infection of mice, a SPI19/T6SS deleted strain of S. Dublin 2229 was less virulent than the wild type strain after oral challenge, but not after IP challenge. The mutant strain also competed significantly poorer than the wild type strain when co-cultured with strains of E. coli, suggesting that this T6SS plays a role in pathogenicity by killing competing bacteria in the intestine. No significant difference was found between wild type S. Gallinarum G9 and its ΔSPI19/T6SS mutant in infection, whether chicken were challenged orally or by the IP route, and the S. Gallinarum G9 ΔSPI19/T6SS strain competed equally well as the wild type strain against strains of E. coli. However, contrary to what was observed with S. Dublin, the wild type G9 strains was significantly more cytotoxic to monocyte derived primary macrophages from hens than the mutant, suggesting that SPI19/T6SS in S. Gallinarum mediates killing of eukaryotic cells. The lack of significant importance of SPI19/T6SS after oral and systemic challenge of chicken was confirmed by knocking out SPI19 in a second strain, J91. Together the results suggest that the T6SS encoded from SPI19 have different roles in the two serovars and that it is a virulence-factor after oral challenge of mice in S. Dublin, while we cannot confirm previous results that SPI19/T6SS influence virulence significantly in S. Gallinarum.
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Affiliation(s)
- Casper Schroll
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Kaisong Huang
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Shahana Ahmed
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Bodil M Kristensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Susanne Elisabeth Pors
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Lotte Jelsbak
- Department of Science and Environment, Roskilde University, Denmark
| | | | - Line E Thomsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens Peter Christensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Peter R Jensen
- Department of Food, Technical University of Denmark, Denmark
| | - John E Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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37
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Wang C, Pu T, Lou W, Wang Y, Gao Z, Hu B, Fan J. Hfq, a RNA Chaperone, Contributes to Virulence by Regulating Plant Cell Wall-Degrading Enzyme Production, Type VI Secretion System Expression, Bacterial Competition, and Suppressing Host Defense Response in Pectobacterium carotovorum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:1166-1178. [PMID: 30198820 DOI: 10.1094/mpmi-12-17-0303-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hfq is a RNA chaperone and participates in a wide range of cellular processes and pathways. In this study, mutation of hfq gene from Pectobacterium carotovorum subsp. carotovorum PccS1 led to significantly reduced virulence and plant cell wall-degrading enzyme (PCWDE) activities. In addition, the mutant exhibited decreased biofilm formation and motility and greatly attenuated carbapenem production as well as secretion of hemolysin coregulated protein (Hcp) as compared with wild-type strain PccS1. Moreover, a higher level of callose deposition was induced in Nicotiana benthamiana leaves when infiltrated with the mutant. A total of 26 small (s)RNA deletion mutants were obtained among a predicted 27 sRNAs, and three mutants exhibited reduced virulence in the host plant. These results suggest that hfq plays a key role in Pectobacterium virulence by positively impacting PCWDE production, secretion of the type VI secretion system, bacterial competition, and suppression of host plant responses.
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Affiliation(s)
- Chunting Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Tianxin Pu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Wangying Lou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yujie Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zishu Gao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Baishi Hu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiaqin Fan
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
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38
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Malabirade A, Habier J, Heintz-Buschart A, May P, Godet J, Halder R, Etheridge A, Galas D, Wilmes P, Fritz JV. The RNA Complement of Outer Membrane Vesicles From Salmonella enterica Serovar Typhimurium Under Distinct Culture Conditions. Front Microbiol 2018; 9:2015. [PMID: 30214435 PMCID: PMC6125333 DOI: 10.3389/fmicb.2018.02015] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/09/2018] [Indexed: 12/20/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs), as well as OMV-associated small RNAs, have been demonstrated to play a role in host-pathogen interactions. The presence of larger RNA transcripts in OMVs has been less studied and their potential role in host-pathogen interactions remains largely unknown. Here we analyze RNA from OMVs secreted by Salmonella enterica serovar Typhimurium (S. Typhimurium) cultured under different conditions, which mimic host-pathogen interactions. S. Typhimurium was grown to exponential and stationary growth phases in minimal growth control medium (phosphate-carbon-nitrogen, PCN), as well as in acidic and phosphate-depleted PCN, comparable to the macrophage environment and inducing therefore the expression of Salmonella pathogenicity island 2 (SPI-2) genes. Moreover, Salmonella pathogenicity island 1 (SPI-1), which is required for virulence during the intestinal phase of infection, was induced by culturing S. Typhimurium to the stationary phase in Lysogeny Broth (LB). For each condition, we identified OMV-associated RNAs that are enriched in the extracellular environment relative to the intracellular space. All RNA classes could be observed, but a vast majority of rRNA was exported in all conditions in variable proportions with a notable decrease in LB SPI-1 inducing media. Several mRNAs and ncRNAs were specifically enriched in/on OMVs dependent on the growth conditions. Important to note is that some RNAs showed identical read coverage profiles intracellularly and extracellularly, whereas distinct coverage patterns were observed for other transcripts, suggesting a specific processing or degradation. Moreover, PCR experiments confirmed that distinct RNAs were present in or on OMVs as full-length transcripts (IsrB-1/2; IsrA; ffs; SsrS; CsrC; pSLT035; 10Sa; rnpB; STM0277; sseB; STM0972; STM2606), whereas others seemed to be rather present in a processed or degraded form. Finally, we show by a digestion protection assay that OMVs are able to prevent enzymatic degradation of given full-length transcripts (SsrS, CsrC, 10Sa, and rnpB). In summary, we show that OMV-associated RNA is clearly different in distinct culture conditions and that at least a fraction of the extracellular RNA is associated as a full-length transcripts with OMVs, indicating that some RNAs are protected by OMVs and thereby leaving open the possibility that those might be functionally active.
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Affiliation(s)
- Antoine Malabirade
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Janine Habier
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Anna Heintz-Buschart
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Patrick May
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Julien Godet
- UMR CNRS 7021, Laboratoire de BioImagerie et Pathologies, Université de Strasbourg, Strasbourg, France
| | - Rashi Halder
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Alton Etheridge
- Pacific Northwest Research Institute, Seattle, WA, United States
| | - David Galas
- Pacific Northwest Research Institute, Seattle, WA, United States
| | - Paul Wilmes
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Joëlle V Fritz
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
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Nguyen SV, Harhay DM, Bono JL, Smith TPL, Fields PI, Dinsmore BA, Santovenia M, Wang R, Bosilevac JM, Harhay GP. Comparative genomics of Salmonella enterica serovar Montevideo reveals lineage-specific gene differences that may influence ecological niche association. Microb Genom 2018; 4:e000202. [PMID: 30052174 PMCID: PMC6159554 DOI: 10.1099/mgen.0.000202] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/05/2018] [Indexed: 01/01/2023] Open
Abstract
Salmonella enterica serovar Montevideo has been linked to recent foodborne illness outbreaks resulting from contamination of products such as fruits, vegetables, seeds and spices. Studies have shown that Montevideo also is frequently associated with healthy cattle and can be isolated from ground beef, yet human salmonellosis outbreaks of Montevideo associated with ground beef contamination are rare. This disparity fuelled our interest in characterizing the genomic differences between Montevideo strains isolated from healthy cattle and beef products, and those isolated from human patients and outbreak sources. To that end, we sequenced 13 Montevideo strains to completion, producing high-quality genome assemblies of isolates from human patients (n=8) or from healthy cattle at slaughter (n=5). Comparative analysis of sequence data from this study and publicly available sequences (n=72) shows that Montevideo falls into four previously established clades, differentially occupied by cattle and human strains. The results of these analyses reveal differences in metabolic islands, environmental adhesion determinants and virulence factors within each clade, and suggest explanations for the infrequent association between bovine isolates and human illnesses.
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Affiliation(s)
- Scott V. Nguyen
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - Dayna M. Harhay
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
| | - James L. Bono
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
| | | | - Patricia I. Fields
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Blake A. Dinsmore
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Monica Santovenia
- Enteric Disease Laboratory Branch, Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Rong Wang
- USDA-ARS-US Meat Animal Research Center, Clay Center, NE 68933, USA
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40
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Wang N, Liu J, Pang M, Wu Y, Awan F, Liles MR, Lu C, Liu Y. Diverse roles of Hcp family proteins in the environmental fitness and pathogenicity of Aeromonas hydrophila Chinese epidemic strain NJ-35. Appl Microbiol Biotechnol 2018; 102:7083-7095. [PMID: 29862449 DOI: 10.1007/s00253-018-9116-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/19/2023]
Abstract
The type VI secretion system (T6SS) has been considered as a crucial factor in bacterial competition and virulence. The hemolysin co-regulated protein (Hcp) is the hallmark of T6SS. The secretion of Hcp in Aeromonas hydrophila Chinese epidemic strain NJ-35 indicated a functional T6SS. In this study, three copies of the hcp gene were identified in the genome of strain NJ-35. We targeted these Hcp family proteins for generating deletion mutants. These mutants showed varying levels in Hcp production, the interaction with other bacteria or eukaryotic cells, and bacterial virulence. Hcp1 was necessary for T6SS assembly and played a predominant role in the bacterial competition; Hcp2 negatively functioned in the biofilm formation and bacterial adhesion and was more involved in the A. hydrophila virulence in zebrafish and survival against the predation of Tetrahymena, and Hcp3 positively influenced the biofilm formation and bacterial adhesion. These findings illustrate that the T6SS of A. hydrophila NJ-35 is active, and the three Hcp family proteins take part in different processes in environmental adaptation and virulence of this bacterium. This study will provide valuable insights into our understanding of microbial interactions and thus contribute to a broader effort to manipulate these interactions for therapeutic or environmental benefit.
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Affiliation(s)
- Nannan Wang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Maoda Pang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Yafeng Wu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Jiangsu Center for Control and Prevention of Aquatic Animal Infectious Diseases, Nanjing, China
| | - Furqan Awan
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Mark R Liles
- Department of Biological Sciences, Auburn University, Auburn, USA
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
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41
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Wheeler NE, Gardner PP, Barquist L. Machine learning identifies signatures of host adaptation in the bacterial pathogen Salmonella enterica. PLoS Genet 2018; 14:e1007333. [PMID: 29738521 PMCID: PMC5940178 DOI: 10.1371/journal.pgen.1007333] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/24/2018] [Indexed: 11/18/2022] Open
Abstract
Emerging pathogens are a major threat to public health, however understanding how pathogens adapt to new niches remains a challenge. New methods are urgently required to provide functional insights into pathogens from the massive genomic data sets now being generated from routine pathogen surveillance for epidemiological purposes. Here, we measure the burden of atypical mutations in protein coding genes across independently evolved Salmonella enterica lineages, and use these as input to train a random forest classifier to identify strains associated with extraintestinal disease. Members of the species fall along a continuum, from pathovars which cause gastrointestinal infection and low mortality, associated with a broad host-range, to those that cause invasive infection and high mortality, associated with a narrowed host range. Our random forest classifier learned to perfectly discriminate long-established gastrointestinal and invasive serovars of Salmonella. Additionally, it was able to discriminate recently emerged Salmonella Enteritidis and Typhimurium lineages associated with invasive disease in immunocompromised populations in sub-Saharan Africa, and within-host adaptation to invasive infection. We dissect the architecture of the model to identify the genes that were most informative of phenotype, revealing a common theme of degradation of metabolic pathways in extraintestinal lineages. This approach accurately identifies patterns of gene degradation and diversifying selection specific to invasive serovars that have been captured by more labour-intensive investigations, but can be readily scaled to larger analyses.
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Affiliation(s)
- Nicole E. Wheeler
- Wellcome Sanger Institute, Hinxton, United Kingdom
- Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- * E-mail: (NEW); (LB)
| | - Paul P. Gardner
- Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Lars Barquist
- Institute for Molecular Infection Biology, University of Wuerzburg, Wuerzburg, Germany
- Helmholtz Institute for RNA-based Infection Research, Wuerzburg, Germany
- * E-mail: (NEW); (LB)
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42
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Ilyas B, Tsai CN, Coombes BK. Evolution of Salmonella-Host Cell Interactions through a Dynamic Bacterial Genome. Front Cell Infect Microbiol 2017; 7:428. [PMID: 29034217 PMCID: PMC5626846 DOI: 10.3389/fcimb.2017.00428] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022] Open
Abstract
Salmonella Typhimurium has a broad arsenal of genes that are tightly regulated and coordinated to facilitate adaptation to the various host environments it colonizes. The genome of Salmonella Typhimurium has undergone multiple gene acquisition events and has accrued changes in non-coding DNA that have undergone selection by regulatory evolution. Together, at least 17 horizontally acquired pathogenicity islands (SPIs), prophage-associated genes, and changes in core genome regulation contribute to the virulence program of Salmonella. Here, we review the latest understanding of these elements and their contributions to pathogenesis, emphasizing the regulatory circuitry that controls niche-specific gene expression. In addition to an overview of the importance of SPI-1 and SPI-2 to host invasion and colonization, we describe the recently characterized contributions of other SPIs, including the antibacterial activity of SPI-6 and adhesion and invasion mediated by SPI-4. We further discuss how these fitness traits have been integrated into the regulatory circuitry of the bacterial cell through cis-regulatory evolution and by a careful balance of silencing and counter-silencing by regulatory proteins. Detailed understanding of regulatory evolution within Salmonella is uncovering novel aspects of infection biology that relate to host-pathogen interactions and evasion of host immunity.
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Affiliation(s)
- Bushra Ilyas
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.,Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Caressa N Tsai
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.,Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Brian K Coombes
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
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43
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Kamber T, Pothier JF, Pelludat C, Rezzonico F, Duffy B, Smits THM. Role of the type VI secretion systems during disease interactions of Erwinia amylovora with its plant host. BMC Genomics 2017; 18:628. [PMID: 28818038 PMCID: PMC5561584 DOI: 10.1186/s12864-017-4010-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 08/02/2017] [Indexed: 12/13/2022] Open
Abstract
Background Type VI secretion systems (T6SS) are widespread among Gram-negative bacteria and have a potential role as essential virulence factors or to maintain symbiotic interactions. Three T6SS gene clusters were identified in the genome of E. amylovora CFBP 1430, of which T6SS-1 and T6SS-3 represent complete T6SS machineries, while T6SS-2 is reduced in its gene content. Results To assess the contribution of T6SSs to virulence and potential transcriptomic changes of E. amylovora CFBP 1430, single and double mutants in two structural genes were generated for T6SS-1 and T6SS-3. Plant assays showed that mutants in T6SS-3 were slightly more virulent in apple shoots while inducing less disease symptoms on apple flowers, indicating that T6SSs have only a minor effect on virulence of E. amylovora CFBP 1430. The mutations led under in vitro conditions to the differential expression of type III secretion systems, iron acquisition, chemotaxis, flagellar, and fimbrial genes. Comparison of the in planta and in vitro transcriptome data sets revealed a common differential expression of three processes and a set of chemotaxis and motility genes. Additional experiments proved that T6SS mutants are impaired in their motility. Conclusion These results suggest that the deletion of T6SSs alters metabolic and motility processes. Nevertheless, the difference in lesion development in apple shoots and flower necrosis of T6SS mutants was indicative that T6SSs influences the disease progression and the establishment of the pathogen on host plants. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-4010-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tim Kamber
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, 8820, Wädenswil, CH, Switzerland
| | - Joël F Pothier
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, 8820, Wädenswil, CH, Switzerland.,Environmental Genomics and Systems Biology Research Group, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), 8820, Wädenswil, CH, Switzerland
| | - Cosima Pelludat
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, 8820, Wädenswil, CH, Switzerland
| | - Fabio Rezzonico
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, 8820, Wädenswil, CH, Switzerland.,Environmental Genomics and Systems Biology Research Group, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), 8820, Wädenswil, CH, Switzerland
| | - Brion Duffy
- Environmental Genomics and Systems Biology Research Group, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), 8820, Wädenswil, CH, Switzerland
| | - Theo H M Smits
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, 8820, Wädenswil, CH, Switzerland. .,Environmental Genomics and Systems Biology Research Group, Institute of Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), 8820, Wädenswil, CH, Switzerland.
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Signal transduction pathway mediated by the novel regulator LoiA for low oxygen tension induced Salmonella Typhimurium invasion. PLoS Pathog 2017; 13:e1006429. [PMID: 28575106 PMCID: PMC5476282 DOI: 10.1371/journal.ppat.1006429] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 06/19/2017] [Accepted: 05/23/2017] [Indexed: 02/03/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a major intestinal pathogen of both humans and animals. Salmonella pathogenicity island 1 (SPI-1)-encoded virulence genes are required for S. Typhimurium invasion. While oxygen (O2) limitation is an important signal for SPI-1 induction under host conditions, how the signal is received and integrated to the central SPI-1 regulatory system in S. Typhimurium is not clear. Here, we report a signal transduction pathway that activates SPI-1 expression in response to low O2. A novel regulator encoded within SPI-14 (STM14_1008), named LoiA (low oxygen induced factor A), directly binds to the promoter and activates transcription of hilD, leading to the activation of hilA (the master activator of SPI-1). Deletion of loiA significantly decreased the transcription of hilA, hilD and other representative SPI-1 genes (sipB, spaO, invH, prgH and invF) under low O2 conditions. The response of LoiA to the low O2 signal is mediated by the ArcB/ArcA two-component system. Deletion of either arcA or arcB significantly decreased transcription of loiA under low O2 conditions. We also confirmed that SPI-14 contributes to S. Typhimurium virulence by affecting invasion, and that loiA is the virulence determinant of SPI-14. Mice infection assays showed that S. Typhimurium virulence was severely attenuated by deletion of either the entire SPI-14 region or the single loiA gene after oral infection, while the virulence was not affected by either deletion after intraperitoneal infection. The signal transduction pathway described represents an important mechanism for S. Typhimurium to sense and respond to low O2 conditions of the host intestinal tract for invasion. SPI-14-encoded loiA is an essential element of this pathway that integrates the low O2 signal into the SPI-1 regulatory system. Acquisition of SPI-14 is therefore crucial for the evolution of S. Typhimurium as an intestinal pathogen. Salmonella enterica serovar Typhimurium (S. Typhimurium) is a major intestinal pathogen of both humans and animals. Salmonella pathogenicity island 1 (SPI-1) is required for host cell invasion by S. Typhimurium. Expression of SPI-1 genes is induced by low oxygen (O2) tension under host conditions, but the relevant regulatory mechanisms are not clear. Here, we report a low O2-induced signal transduction pathway for the activation of SPI-1 expression in S. Typhimurium. A novel regulator, STM14_1008 (named LoiA), encoded within SPI-14 directly activates hilD, which in turn activates hilA (the master activator of SPI-1), and thus other SPI-1 genes under O2-limited conditions. The response of LoiA to the low O2 signal is mediated by the ArcB/ArcA two-component system. We also confirmed that SPI-14 contributes to S. Typhimurium virulence by affecting invasion, with loiA as the virulence determinant. This novel SPI-1 activation pathway can be used by S. Typhimurium to sense and respond to low O2 conditions of the host intestinal tract for invasion. Acquisition of SPI-14 is therefore very important for the evolution of S. Typhimurium virulence by providing an essential component of this pathway, loiA.
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45
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Martínez-Flores I, Pérez-Morales D, Sánchez-Pérez M, Paredes CC, Collado-Vides J, Salgado H, Bustamante VH. In silico clustering of Salmonella global gene expression data reveals novel genes co-regulated with the SPI-1 virulence genes through HilD. Sci Rep 2016; 6:37858. [PMID: 27886269 PMCID: PMC5122947 DOI: 10.1038/srep37858] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/02/2016] [Indexed: 01/04/2023] Open
Abstract
A wide variety of Salmonella enterica serovars cause intestinal and systemic infections to humans and animals. Salmonella Patogenicity Island 1 (SPI-1) is a chromosomal region containing 39 genes that have crucial virulence roles. The AraC-like transcriptional regulator HilD, encoded in SPI-1, positively controls the expression of the SPI-1 genes, as well as of several other virulence genes located outside SPI-1. In this study, we applied a clustering method to the global gene expression data of S. enterica serovar Typhimurium from the COLOMBOS database; thus genes that show an expression pattern similar to that of SPI-1 genes were selected. This analysis revealed nine novel genes that are co-expressed with SPI-1, which are located in different chromosomal regions. Expression analyses and protein-DNA interaction assays showed regulation by HilD for six of these genes: gtgE, phoH, sinR, SL1263 (lpxR) and SL4247 were regulated directly, whereas SL1896 was regulated indirectly. Interestingly, phoH is an ancestral gene conserved in most of bacteria, whereas the other genes show characteristics of genes acquired by Salmonella. A role in virulence has been previously demonstrated for gtgE, lpxR and sinR. Our results further expand the regulon of HilD and thus identify novel possible Salmonella virulence genes.
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Affiliation(s)
- Irma Martínez-Flores
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Deyanira Pérez-Morales
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Mishael Sánchez-Pérez
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Claudia C Paredes
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
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46
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Riquelme S, Varas M, Valenzuela C, Velozo P, Chahin N, Aguilera P, Sabag A, Labra B, Álvarez SA, Chávez FP, Santiviago CA. Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum. Front Microbiol 2016; 7:1305. [PMID: 27602025 PMCID: PMC4993766 DOI: 10.3389/fmicb.2016.01305] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/08/2016] [Indexed: 01/08/2023] Open
Abstract
The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process. To do this, we performed infection assays using axenic cultures of D. discoideum co-cultured with wild-type S. Typhimurium and/or defined mutant strains. Our results confirmed that wild-type S. Typhimurium is able to survive intracellularly in D. discoideum. In contrast, mutants ΔaroA and ΔwaaL are defective in intracellular survival in this amoeba. Next, we included in our study a group of mutants in genes directly linked to Salmonella virulence. Of note, mutants ΔinvA, ΔssaD, ΔclpV, and ΔphoPQ also showed an impaired ability to survive intracellularly in D. discoideum. This indicates that S. Typhimurium requires a functional biosynthetic pathway of aromatic compounds, a lipopolysaccharide containing a complete O-antigen, the type III secretion systems (T3SS) encoded in SPI-1 and SPI-2, the type VI secretion system (T6SS) encoded in SPI-6 and PhoP/PhoQ two-component system to survive in D. discoideum. To our knowledge, this is the first report on the requirement of O-antigen and T6SS in the survival of Salmonella within amoebae. In addition, mutants ΔinvA and ΔssaD were internalized in higher numbers than the wild-type strain during competitive infections, suggesting that S. Typhimurium requires the T3SS encoded in SPI-1 and SPI-2 to evade phagocytosis by D. discoideum. Altogether, these results indicate that S. Typhimurium exploits a common set of genes and molecular mechanisms to survive within amoeba and animal host cells. The use of D. discoideum as a model for host-pathogen interactions will allow us to discover the gene repertoire used by Salmonella to survive inside the amoeba and to study the cellular processes that are affected during infection.
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Affiliation(s)
- Sebastián Riquelme
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Macarena Varas
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de ChileSantiago, Chile
| | - Camila Valenzuela
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Paula Velozo
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Nicolás Chahin
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Paulina Aguilera
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de ChileSantiago, Chile
| | - Andrea Sabag
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Bayron Labra
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Sergio A. Álvarez
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Francisco P. Chávez
- Laboratorio de Microbiología de Sistemas, Departamento de Biología, Facultad de Ciencias, Universidad de ChileSantiago, Chile
| | - Carlos A. Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
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Mitchell G, Chen C, Portnoy DA. Strategies Used by Bacteria to Grow in Macrophages. Microbiol Spectr 2016; 4:10.1128/microbiolspec.MCHD-0012-2015. [PMID: 27337444 PMCID: PMC4922531 DOI: 10.1128/microbiolspec.mchd-0012-2015] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Indexed: 12/24/2022] Open
Abstract
Intracellular bacteria are often clinically relevant pathogens that infect virtually every cell type found in host organisms. However, myeloid cells, especially macrophages, constitute the primary cells targeted by most species of intracellular bacteria. Paradoxically, macrophages possess an extensive antimicrobial arsenal and are efficient at killing microbes. In addition to their ability to detect and signal the presence of pathogens, macrophages sequester and digest microorganisms using the phagolysosomal and autophagy pathways or, ultimately, eliminate themselves through the induction of programmed cell death. Consequently, intracellular bacteria influence numerous host processes and deploy sophisticated strategies to replicate within these host cells. Although most intracellular bacteria have a unique intracellular life cycle, these pathogens are broadly categorized into intravacuolar and cytosolic bacteria. Following phagocytosis, intravacuolar bacteria reside in the host endomembrane system and, to some extent, are protected from the host cytosolic innate immune defenses. However, the intravacuolar lifestyle requires the generation and maintenance of unique specialized bacteria-containing vacuoles and involves a complex network of host-pathogen interactions. Conversely, cytosolic bacteria escape the phagolysosomal pathway and thrive in the nutrient-rich cytosol despite the presence of host cell-autonomous defenses. The understanding of host-pathogen interactions involved in the pathogenesis of intracellular bacteria will continue to provide mechanistic insights into basic cellular processes and may lead to the discovery of novel therapeutics targeting infectious and inflammatory diseases.
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Affiliation(s)
- Gabriel Mitchell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
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Abstract
The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell. Although the assembly and the mechanism of action are conserved across species, the repertoire of secreted toxins and the diversity of the regulatory mechanisms and of target cells make the T6SS a highly versatile secretion system. The T6SS is particularly represented in Escherichia coli pathotypes and Salmonella serotypes. In this review we summarize the current knowledge regarding the prevalence, the assembly, the regulation, and the roles of the T6SS in E. coli, Salmonella, and related species.
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Affiliation(s)
- Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Centre National de la Recherche Scientifique (CNRS) - Aix-Marseille Université, UMR 7255, 13402 Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Centre National de la Recherche Scientifique (CNRS) - Aix-Marseille Université, UMR 7255, 13402 Marseille Cedex 20, France
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49
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Acetylation of Lysine 201 Inhibits the DNA-Binding Ability of PhoP to Regulate Salmonella Virulence. PLoS Pathog 2016; 12:e1005458. [PMID: 26943369 PMCID: PMC4778762 DOI: 10.1371/journal.ppat.1005458] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 01/25/2016] [Indexed: 12/21/2022] Open
Abstract
The two-component system PhoP-PhoQ is highly conserved in bacteria and regulates virulence in response to various signals for bacteria within the mammalian host. Here, we demonstrate that PhoP could be acetylated by Pat and deacetylated by deacetylase CobB enzymatically in vitro and in vivo in Salmonella Typhimurium. Specifically, the conserved lysine residue 201(K201) in winged helix-turn-helix motif at C-terminal DNA-binding domain of PhoP could be acetylated, and its acetylation level decreases dramatically when bacteria encounter low magnesium, acid stress or phagocytosis of macrophages. PhoP has a decreased acetylation and increased DNA-binding ability in the deletion mutant of pat. However, acetylation of K201 does not counteract PhoP phosphorylation, which is essential for PhoP activity. In addition, acetylation of K201 (mimicked by glutamine substitute) in S. Typhimurium causes significantly attenuated intestinal inflammation as well as systemic infection in mouse model, suggesting that deacetylation of PhoP K201 is essential for Salmonella pathogenesis. Therefore, we propose that the reversible acetylation of PhoP K201 may ensure Salmonella promptly respond to different stresses in host cells. These findings suggest that reversible lysine acetylation in the DNA-binding domain, as a novel regulatory mechanism of gene expression, is involved in bacterial virulence across microorganisms.
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50
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Linares D, Jean N, Van Overtvelt P, Ouidir T, Hardouin J, Blache Y, Molmeret M. The marine bacteria Shewanella frigidimarina NCIMB400 upregulates the type VI secretion system during early biofilm formation. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:110-121. [PMID: 26617163 DOI: 10.1111/1758-2229.12358] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/19/2015] [Indexed: 06/05/2023]
Abstract
Shewanella sp. are facultative anaerobic Gram-negative bacteria, extensively studied for their electron transfer ability. Shewanella frigidimarina has been detected and isolated from marine environments, and in particular, from biofilms. However, its ability to adhere to surfaces and form a biofilm is poorly understood. In this study, we show that the ability to adhere and to form a biofilm of S. frigidimarina NCIMB400 is significantly higher than that of Shewanella oneidensis in our conditions. We also show that this strain forms a biofilm in artificial seawater, whereas in Luria-Bertani, this capacity is reduced. To identify proteins involved in early biofilm formation, a proteomic analysis of sessile versus planktonic membrane-enriched fractions allowed the identification of several components of the same type VI secretion system gene cluster: putative Hcp1 and ImpB proteins as well as a forkhead-associated domain-containing protein. The upregulation of Hcp1 a marker of active translocation has been confirmed using quantitative reverse transcription polymerase chain reaction. Our data demonstrated the presence of a single and complete type VI secretion system in S. frigidimarina NCIMB400 genome, upregulated in sessile compared with planktonic conditions. The fact that three proteins including the secreted protein Hcp1 have been identified may suggest that this type VI secretion system is functional.
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Affiliation(s)
- Denis Linares
- Université de Toulon, MAPIEM, EA4323, 83957, La Garde, France
| | | | | | - Tassadit Ouidir
- UMR 6270 CNRS, Laboratoire Polymères, Biopolymères, Surfaces, Université de Rouen, Mont-Saint-Aignan, F-76820, France
| | - Julie Hardouin
- UMR 6270 CNRS, Laboratoire Polymères, Biopolymères, Surfaces, Université de Rouen, Mont-Saint-Aignan, F-76820, France
| | - Yves Blache
- Université de Toulon, MAPIEM, EA4323, 83957, La Garde, France
| | - Maëlle Molmeret
- Université de Toulon, MAPIEM, EA4323, 83957, La Garde, France
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