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Lê-Bury P, Echenique-Rivera H, Pizarro-Cerdá J, Dussurget O. Determinants of bacterial survival and proliferation in blood. FEMS Microbiol Rev 2024; 48:fuae013. [PMID: 38734892 PMCID: PMC11163986 DOI: 10.1093/femsre/fuae013] [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: 11/06/2023] [Revised: 04/29/2024] [Accepted: 05/10/2024] [Indexed: 05/13/2024] Open
Abstract
Bloodstream infection is a major public health concern associated with high mortality and high healthcare costs worldwide. Bacteremia can trigger fatal sepsis whose prevention, diagnosis, and management have been recognized as a global health priority by the World Health Organization. Additionally, infection control is increasingly threatened by antimicrobial resistance, which is the focus of global action plans in the framework of a One Health response. In-depth knowledge of the infection process is needed to develop efficient preventive and therapeutic measures. The pathogenesis of bloodstream infection is a dynamic process resulting from the invasion of the vascular system by bacteria, which finely regulate their metabolic pathways and virulence factors to overcome the blood immune defenses and proliferate. In this review, we highlight our current understanding of determinants of bacterial survival and proliferation in the bloodstream and discuss their interactions with the molecular and cellular components of blood.
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Affiliation(s)
- Pierre Lê-Bury
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
- Université Paris-Saclay, Inserm, CEA, Center for Immunology of Viral, Autoimmune, Hematological and Bacterial Diseases (IMVA-HB/IDMIT), 18 route du Panorama, 92260 Fontenay-aux-Roses, France
| | - Hebert Echenique-Rivera
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
| | - Javier Pizarro-Cerdá
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
- Institut Pasteur, Université Paris Cité, Yersinia National Reference Laboratory, WHO Collaborating Research & Reference Centre for Plague FRA-146, 28 rue du Dr Roux, 75015 Paris, France
| | - Olivier Dussurget
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, 28 rue du Dr Roux, 75015 Paris, France
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Xiang T, Zhou W, Xu C, Xu J, Liu R, Wang N, Xu L, Zhao Y, Luo M, Mo X, Mao Z, Wan Y. Transcriptomic Analysis Reveals Competitive Growth Advantage of Non-pigmented Serratia marcescens Mutants. Front Microbiol 2022; 12:793202. [PMID: 35058908 PMCID: PMC8764370 DOI: 10.3389/fmicb.2021.793202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 11/26/2021] [Indexed: 11/26/2022] Open
Abstract
Serratia marcescens is a common bacterium well-known for the red secondary metabolite prodigiosin. However, color mutants have long been described. Non-pigmented strains can be found to exist both naturally and under laboratory conditions. It is unclear why S. marcescens loses prodigiosin synthesis capacity in certain conditions. In the present study, we find that the spontaneous color mutants arise within a few generations (about five passages) and rapidly replace the wild-type parent cells (about 24 passages), which indicates a growth advantage of the former. Although, the loss of prodigiosin synthesis genes (pigA-N) is frequently reported as the major reason for pigment deficiency, it was unexpected that the whole gene cluster is completely preserved in the different color morphotypes. Comparative transcriptomic analysis indicates a dramatic variation at the transcriptional level. Most of the pig genes are significantly downregulated in the color morphotypes which directly lead to prodigiosin dyssynthesis. Besides, the transcriptional changes of several other genes have been noticed, of which transcriptional regulators, membrane proteins, and nearly all type VI secretion system (T6SS) components are generally downregulated, while both amino acid metabolite and transport systems are activated. In addition, we delete the transcription regulator slyA to generate a non-pigmented mutant. The ΔslyA strain loses prodigiosin synthesis capacity, but has a higher cell density, and surprisingly enhances the virulence as an entomopathogen. These data indicate that S. marcescens shuts down several high-cost systems and activates the amino acid degradation and transport pathways at the transcriptional level to obtain extra resources, which provides new insights into the competitive growth advantage of bacterial spontaneous color mutants.
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Affiliation(s)
- Tingting Xiang
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Wei Zhou
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Cailing Xu
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Jing Xu
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Rui Liu
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Nuo Wang
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Liang Xu
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Yu Zhao
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Minhui Luo
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Xiaoxin Mo
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Zeyang Mao
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
| | - Yongji Wan
- Laboratory of Invertebrate Pathology and Applied Microbiology, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing, China
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Kucukyildirim S. Whole-population genomic sequencing reveals the mutational profiles of the antibiotic-treated Escherichia coli populations. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-021-00959-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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4
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The sRNA MicC downregulates hilD translation to control the SPI1 T3SS in Salmonella enterica serovar Typhimurium. J Bacteriol 2021; 204:e0037821. [PMID: 34694902 DOI: 10.1128/jb.00378-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Salmonella enterica serovar Typhimurium invades the intestinal epithelium and induces inflammatory diarrhea using the Salmonella pathogenicity island 1 (SPI1) type III secretion system (T3SS). Expression of the SPI1 T3SS is controlled by three AraC-like regulators, HilD, HilC and RtsA, which form a feed-forward regulatory loop that leads to activation of hilA, encoding the main transcriptional regulator of the T3SS structural genes. This complex system is affected by numerous regulatory proteins and environmental signals, many of which act at the level of hilD mRNA translation or HilD protein function. Here, we show that the sRNA MicC blocks translation of the hilD mRNA by base pairing near the ribosome binding site. MicC does not induce degradation of the hilD message. Our data indicate that micC is transcriptionally activated by SlyA, and SlyA feeds into the SPI1 regulatory network solely through MicC. Transcription of micC is negatively regulated by the OmpR/EnvZ two-component system, but this regulation is dependent on SlyA. OmpR/EnvZ control SPI1 expression partially through MicC, but also affect expression through other pathways, including an EnvZ-dependent, OmpR-independent mechanism. MicC-mediated regulation plays a role during infection, as evidenced by a SPI1 T3SS-dependent increase in Salmonella fitness in the intestine in the micC deletion mutant. These results further elucidate the complex regulatory network controlling SPI1 expression and add to the list of sRNAs that control this primary virulence factor. IMPORTANCE The Salmonella SPI1 T3SS is the primary virulence factor required for causing intestinal disease and initiating systemic infection. The system is regulated in response to a large variety of environmental and physiological factors such that the T3SS is expressed at only the appropriate time and place in the host during infection. Here we show how the sRNA MicC affects expression of the system. This work adds to our detailed mechanistic studies aimed at a complete understanding of the regulatory circuit.
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Li Z, Zhang L, Song Q, Wang G, Yang W, Tang H, Srinivasan R, Lin L, Lin X. Proteomics Analysis Reveals Bacterial Antibiotics Resistance Mechanism Mediated by ahslyA Against Enoxacin in Aeromonas hydrophila. Front Microbiol 2021; 12:699415. [PMID: 34168639 PMCID: PMC8217646 DOI: 10.3389/fmicb.2021.699415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 05/17/2021] [Indexed: 12/26/2022] Open
Abstract
Bacterial antibiotic resistance is a serious global problem; the underlying regulatory mechanisms are largely elusive. The earlier reports states that the vital role of transcriptional regulators (TRs) in bacterial antibiotic resistance. Therefore, we have investigated the role of TRs on enoxacin (ENX) resistance in Aeromonas hydrophila in this study. A label-free quantitative proteomics method was utilized to compare the protein profiles of the ahslyA knockout and wild-type A. hydrophila strains under ENX stress. Bioinformatics analysis showed that the deletion of ahslyA triggers the up-regulated expression of some vital antibiotic resistance proteins in A. hydrophila upon ENX stress and thereby reduce the pressure by preventing the activation of SOS repair system. Moreover, ahslyA directly or indirectly induced at least 11 TRs, which indicates a complicated regulatory network under ENX stress. We also deleted six selected genes in A. hydrophila that altered in proteomics data in order to evaluate their roles in ENX stress. Our results showed that genes such as AHA_0655, narQ, AHA_3721, AHA_2114, and AHA_1239 are regulated by ahslyA and may be involved in ENX resistance. Overall, our data demonstrated the important role of ahslyA in ENX resistance and provided novel insights into the effects of transcriptional regulation on antibiotic resistance in bacteria.
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Affiliation(s)
- Zhen Li
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Zhangzhou Health Vocational College, Zhangzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China.,Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lishan Zhang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Qingli Song
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Guibin Wang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences, Beijing Institute of Lifeomics, Beijing, China
| | - Wenxiao Yang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Huamei Tang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Ramanathan Srinivasan
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Ling Lin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China
| | - Xiangmin Lin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Agriculture and Forestry University, Fujian Province University, Fuzhou, China.,Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, China
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Kotecka K, Kawalek A, Kobylecki K, Bartosik AA. The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:ijms22083982. [PMID: 33921535 PMCID: PMC8070244 DOI: 10.3390/ijms22083982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections that are especially dangerous for immunocompromised patients. The eradication of P. aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins, mainly acting as repressors, which are involved in response to various environmental signals. In this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase, a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in osmoadaptation control in P. aeruginosa.
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Sousa Gerós A, Simmons A, Drakesmith H, Aulicino A, Frost JN. The battle for iron in enteric infections. Immunology 2020; 161:186-199. [PMID: 32639029 PMCID: PMC7576875 DOI: 10.1111/imm.13236] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/01/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential element for almost all living organisms, but can be extremely toxic in high concentrations. All organisms must therefore employ homeostatic mechanisms to finely regulate iron uptake, usage and storage in the face of dynamic environmental conditions. The critical step in mammalian systemic iron homeostasis is the fine regulation of dietary iron absorption. However, as the gastrointestinal system is also home to >1014 bacteria, all of which engage in their own programmes of iron homeostasis, the gut represents an anatomical location where the inter-kingdom fight for iron is never-ending. Here, we explore the molecular mechanisms of, and interactions between, host and bacterial iron homeostasis in the gastrointestinal tract. We first detail how mammalian systemic and cellular iron homeostasis influences gastrointestinal iron availability. We then focus on two important human pathogens, Salmonella and Clostridia; despite their differences, they exemplify how a bacterial pathogen must navigate and exploit this web of iron homeostasis interactions to avoid host nutritional immunity and replicate successfully. We then reciprocally explore how iron availability interacts with the gastrointestinal microbiota, and the consequences of this on mammalian physiology and pathogen iron acquisition. Finally, we address how understanding the battle for iron in the gastrointestinal tract might inform clinical practice and inspire new treatments for important diseases.
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Affiliation(s)
- Ana Sousa Gerós
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Alison Simmons
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Hal Drakesmith
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
| | - Anna Aulicino
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
- Translational Gastroenterology UnitJohn Radcliffe HospitalOxfordUK
| | - Joe N. Frost
- MRC Human Immunology UnitWeatherall Institute of Molecular MedicineUniversity of OxfordOxfordUK
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Bartoli J, Viala JP, Bouveret E. SlyA Transcriptional Regulator Is Not Directly Affected by ppGpp Levels. Front Microbiol 2020; 11:1856. [PMID: 32849447 PMCID: PMC7417354 DOI: 10.3389/fmicb.2020.01856] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/15/2020] [Indexed: 12/11/2022] Open
Abstract
The SlyA transcriptional regulator controls the expression of genes involved in virulence and production of surface components in S. Typhimurium and E. coli. Its mode of action is mainly explained by its antagonism with the H-NS repressor for the same DNA binding regions. Interestingly, it has been reported that the alarmone ppGpp promotes SlyA dimerization and DNA binding at the promoter of pagC, enhancing the expression of this gene in Salmonella. A recurring problem in the field of stringent response has been to find a way of following ppGpp levels in vivo in real time. We thought that SlyA, as a ppGpp responsive ligand, was a perfect candidate for the development of a specific ppGpp biosensor. Therefore, we decided to characterize in depth this SlyA control by ppGpp. However, using various genes whose expression is activated by SlyA, as reporters, we showed that ppGpp does not affect SlyA regulation in vivo. In addition, modulating ppGpp levels did not affect SlyA dimerization in vivo, and did not impact its binding to DNA in vitro. We finally showed that ppGpp is required for the expression of hlyE in E. coli, a gene also activated by SlyA, and propose that both regulators are independently required for hlyE expression. The initial report of ppGpp action on SlyA might be explained by a similar action of SlyA and ppGpp on pagC expression, and the complexity of promoters controlled by several global regulators, such as the promoters of pagC in Salmonella or hlyE in E. coli.
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Affiliation(s)
- Julia Bartoli
- LISM, Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille University, Marseille, France
| | - Julie Pamela Viala
- LISM, Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille University, Marseille, France
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Abraham A, Ifeanyi SS, Muinah F, Ibidunni Oreoluwa BS, Coulibaly KJ, Adeyemi AI. Plasmid profile and role in virulence of salmonella enterica serovars isolated from food animals and humans in Lagos Nigeria. Pathog Glob Health 2020; 113:282-287. [PMID: 31818238 DOI: 10.1080/20477724.2019.1691364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Infections caused by non-typhoidal Salmonella (NTS) are common around the world, with high morbidity and mortality rates recorded annually. Salmonella serovars harbor plasmids of various sizes which may play roles in antibiotic resistance and virulence. The aim of this study was to profile and determine the role of plasmids in ciprofloxacin resistance and virulence of Salmonella serovars. Using alkaline lysis method 25 NTS serovars from food animals and humans were assayed for plasmids. Isolates ability to resist healthy human serum, bind congo red, produce hemolysin and susceptibility to ciprofloxacin before and after plasmid curing were evaluated. Mobility of plasmids was determined by conjugation. Fifteen (60%) of the 25 Salmonella serovars harbored plasmids with sizes ranging from 0.4 to 38.4 kb. S. Budapest serovars harbored 5-9 plasmids, while S. Essen and S. Mura had six plasmids each. S. Chomedey and a S. Budapest serovar were sensitive to ciprofloxacin after plasmid curing while other serovars remained resistant to ciprofloxacin after plasmid curing. All Salmonella isolates had the ability to withstand human serum before and after plasmid curing, however, some serovars lost their ability to bind congo red after plasmid curing. All Salmonella isolates that initially displayed hemolysin activity retained their ability after curing. Thirteen (86.7%) of the 15 serovars that harbored plasmids conjugatively transferred their plasmids to E. coli K-12 (DH5α). Having Salmonella serovars that harbor transferrable plasmids in the food chain can drive antibiotic resistance and enhanced virulence of otherwise less virulence strains.
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Affiliation(s)
- Ajayi Abraham
- Department of Microbiology, University of Lagos Akoka, Lagos, Nigeria
| | - Smith Stella Ifeanyi
- Molecular Biology and Biotechnology Department, Nigerian Institute of Medical Research Lagos, Lagos, Nigeria
| | - Fowora Muinah
- Molecular Biology and Biotechnology Department, Nigerian Institute of Medical Research Lagos, Lagos, Nigeria
| | | | - Kalpy Julien Coulibaly
- Centre Nationale de Référence de Salmonella, Laboratoire de Bactériologie et Virologie Institut Pasteur de Côte d'Ivoire, Côte d'Ivoire
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The evolution of MarR family transcription factors as counter-silencers in regulatory networks. Curr Opin Microbiol 2020; 55:1-8. [PMID: 32044654 DOI: 10.1016/j.mib.2020.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/29/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022]
Abstract
Gene duplication facilitates the evolution of biological complexity, as one copy of a gene retains its original function while a duplicate copy can acquire mutations that would otherwise diminish fitness. Duplication has played a particularly important role in the evolution of regulatory networks by permitting novel regulatory interactions and responses to stimuli. The diverse MarR family of transcription factors (MFTFs) illustrate this concept, ranging from highly specific repressors of single operons to pleiotropic global regulators controlling hundreds of genes. MFTFs are often genetically and functionally linked to antimicrobial efflux systems. However, the SlyA MFTF lineage in the Enterobacteriaceae plays little or no role in regulating efflux but rather functions as transcriptional counter-silencers, which alleviate xenogeneic silencing of horizontally acquired genes and facilitate bacterial evolution by horizontal gene transfer. This review will explore recent advances in our understanding of MFTF traits that have contributed to their functional evolution.
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11
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Gong Z, Li H, Cai Y, Stojkoska A, Xie J. Biology of MarR family transcription factors and implications for targets of antibiotics against tuberculosis. J Cell Physiol 2019; 234:19237-19248. [PMID: 31012115 DOI: 10.1002/jcp.28720] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/03/2019] [Accepted: 04/10/2019] [Indexed: 12/12/2022]
Abstract
The emergence of multidrug resistant (MDR) Mycobacterium tuberculosis strains and increased incidence of HIV coinfection fueled the difficulty in controlling tuberculosis (TB). MarR (multiple antibiotic resistance regulator) family transcription factors can regulate marRAB operon and are involved in resistance to multiple environmental stresses. We have summarized the structure, function, distribution, and regulation of the MarR family proteins, as well as their implications for novel targets for antibiotics, especially for tuberculosis.
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Affiliation(s)
- Zhen Gong
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Hui Li
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Yuhua Cai
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Andrea Stojkoska
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
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12
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A Dopamine-Responsive Signal Transduction Controls Transcription of Salmonella enterica Serovar Typhimurium Virulence Genes. mBio 2019; 10:mBio.02772-18. [PMID: 30992361 PMCID: PMC6469979 DOI: 10.1128/mbio.02772-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have shown that the ligand-responsive MarR family member SlyA plays an important role in transcription activation of multiple virulence genes in Salmonella enterica serovar Typhimurium by responding to guanosine tetraphosphate (ppGpp). Here, we demonstrate that another MarR family member, EmrR, is required for virulence of S. Typhimurium and another enteric bacterium, Yersinia pestis EmrR is found to activate transcription of an array of virulence determinants, including Salmonella pathogenicity island 2 (SPI-2) genes and several divergent operons, which have been shown to be activated by SlyA and the PhoP/PhoQ two-component system. We studied the regulatory effect of EmrR on one of these genetic loci, i.e., the pagC-pagD divergent operon, and characterized a catecholamine neurotransmitter, dopamine, as an EmrR-sensed signal. Dopamine acts on EmrR to reduce its ability to bind to the target promoters, thus functioning as a negative signal to downregulate this EmrR-activated transcription. EmrR can bind to AT-rich sequences, which particularly overlap the SlyA and PhoP binding sites in the pagC-pagD divergent promoter. EmrR is a priming transcription regulator that binds its target promoters prior to successive transcription activators, by which it displaces universal silencer H-NS from these promoters and facilitates successive regulators to bind these regions. Regulation of the Salmonella-specific gene in Escherichia coli and Y. pestis reveals that EmrR-dependent regulation is conserved in enteric bacteria. These observations suggest that EmrR is a transcription activator to control the expression of virulence genes, including the SPI-2 genes. Dopamine can act on the EmrR-mediated signal transduction, thus downregulating expression of these virulence factors.IMPORTANCE In this study, MarR family regulator EmrR is identified as a novel virulence factor of enteric bacteria, here exemplified by Salmonella enterica serovar Typhimurium and Yersinia pestis EmrR exerts an essential effect as a transcription activator for expression of virulence determinants, including Salmonella pathogenicity island 2 genes and a set of horizontally acquired genetic loci that formed divergent operons. EmrR senses the neurotransmitter dopamine and is subsequently released from target promoters, resulting in downregulation of the virulence gene expression. Through this action on EmrR, dopamine can weaken Salmonella resistance against host defense mechanisms. This provides an explanation for the previous observation that dopamine inhibits bacterial infection in animal gastrointestinal tracts. Our findings provide evidence that this neurotransmitter can modulate bacterial gene expression through interaction with virulence regulator EmrR.
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Regulatory Effect of SlyA on rcsB Expression in Salmonella enterica Serovar Typhimurium. J Bacteriol 2019; 201:JB.00673-18. [PMID: 30510144 DOI: 10.1128/jb.00673-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/21/2018] [Indexed: 11/20/2022] Open
Abstract
The Salmonella enterica serovar Typhimurium RcsCDB system regulates the synthesis of colanic acid and the flagellum as well as the expression of virulence genes. We previously demonstrated that the rcsC11 mutant, which constitutively activates the RcsB regulator, attenuates Salmonella virulence in an animal model. This attenuated phenotype was also produced by deletion of the slyA gene. In this work, we investigated if this antagonistic behavior is produced by modulating the expression of both regulator-encoding genes. We demonstrated that SlyA overproduction negatively regulates rcsB transcription. A bioinformatics analysis enabled us to identify putative SlyA binding sites on both promoters, P rcsDB and P rcsB , which control rcsB transcriptional levels. We also determined that SlyA is able to recognize and bind to these predicted sites to modulate the activity of both rcsB promoters. According to these results, SlyA represses rcsB transcription by direct binding to specific sites located on the rcsB promoters, thus accounting for the attenuated/virulence antagonistic behaviors. Moreover, we showed that the opposite effect between both regulators also physiologically affects the Salmonella motility phenotype. In this sense, we observed that under SlyA overproduction, P rcsB is repressed, and consequently, bacterial motility is increased. On the basis of these results, we suggest that during infection, the different RcsB levels produced act as a switch between the virulent and attenuated forms of Salmonella Thereby, we propose that higher concentrations of RcsB tilt the balance toward the attenuated form, while absence or low concentrations resulting from SlyA overproduction tilt the balance toward the virulent form.IMPORTANCE The antagonistic behavior of RcsB and SlyA on virulence gene expression led us to hypothesize that there is interplay between both regulators in a regulatory network and these could be considered coordinators of this process. Here, we report that the SlyA virulence factor influences motility behavior by controlling rcsB transcription from the P rcsB promoter. We also demonstrate that SlyA negatively affects the expression of the rcsB gene by direct binding to P rcsDB and P rcsB promoters. We suggest that different levels of RcsB act as a switch between the virulent and attenuated forms of Salmonella, where high concentrations of the regulator tend to tilt the balance toward the attenuated form and low concentrations or its absence tilt it toward the virulent form.
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Pardo-Esté C, Hidalgo AA, Aguirre C, Briones AC, Cabezas CE, Castro-Severyn J, Fuentes JA, Opazo CM, Riedel CA, Otero C, Pacheco R, Valvano MA, Saavedra CP. The ArcAB two-component regulatory system promotes resistance to reactive oxygen species and systemic infection by Salmonella Typhimurium. PLoS One 2018; 13:e0203497. [PMID: 30180204 PMCID: PMC6122832 DOI: 10.1371/journal.pone.0203497] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/21/2018] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica Serovar Typhimurium (S. Typhimurium) is an intracellular bacterium that overcomes host immune system barriers for successful infection. The bacterium colonizes the proximal small intestine, penetrates the epithelial layer, and is engulfed by macrophages and neutrophils. Intracellularly, S. Typhimurium encounters highly toxic reactive oxygen species including hydrogen peroxide and hypochlorous acid. The molecular mechanisms of Salmonella resistance to intracellular oxidative stress is not completely understood. The ArcAB two-component system is a global regulatory system that responds to oxygen. In this work, we show that the ArcA response regulator participates in Salmonella adaptation to changing oxygen levels and is also involved in promoting intracellular survival in macrophages and neutrophils, enabling S. Typhimurium to successfully establish a systemic infection.
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Affiliation(s)
- Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alejandro A. Hidalgo
- Laboratorio de Patogenesis Bacteriana, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Camila Aguirre
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alan C. Briones
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Carolina E. Cabezas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan A. Fuentes
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Cecilia M. Opazo
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Claudia A. Riedel
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Carolina Otero
- Center for Integrative Medicine and Innovative Science (CIMIS), Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Rodrigo Pacheco
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Santiago, Chile
- Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Miguel A. Valvano
- The Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
- * E-mail:
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Zhang B, Ran L, Wu M, Li Z, Jiang J, Wang Z, Cheng S, Fu J, Liu X. Shigellaflexneri Regulator SlyA Controls Bacterial Acid Resistance by Directly Activating the Glutamate Decarboxylation System. Front Microbiol 2018; 9:2071. [PMID: 30233544 PMCID: PMC6128205 DOI: 10.3389/fmicb.2018.02071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/14/2018] [Indexed: 01/02/2023] Open
Abstract
Shigella flexneri is an important foodborne bacterial pathogen with infectious dose as low as 10–100 cells. SlyA, a transcriptional regulator of the MarR family, has been shown to regulate virulence in a closely related bacterial pathogen, Salmonella Typhimurium. However, the regulatory role of SlyA in S. flexneri is less understood. Here we applied unbiased proteomic profiling to define the SlyA regulon in S. flexneri. We found that the genetic ablation of slyA led to the alteration of 18 bacterial proteins among over 1400 identifications. Intriguingly, most down-regulated proteins (whose expression is SlyA-dependent) were associated with bacterial acid resistance such as the glutamate decarboxylation system. We further demonstrated that SlyA directly regulates the expression of GadA, a glutamate decarboxylase, by binding to the promotor region of its coding gene. Importantly, overexpression of GadA was able to rescue the survival defect of the ΔslyA mutant under acid stress. Therefore, our study highlights a major role of SlyA in controlling S. flexneri acid resistance and provides a molecular mechanism underlying such regulation as well.
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Affiliation(s)
- Buyu Zhang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Longhao Ran
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Mei Wu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Zezhou Li
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Jiezhang Jiang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Zhen Wang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Sen Cheng
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Jiaqi Fu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Xiaoyun Liu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
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Identification of Two Regulators of Virulence That Are Conserved in Klebsiella pneumoniae Classical and Hypervirulent Strains. mBio 2018; 9:mBio.01443-18. [PMID: 30087173 PMCID: PMC6083908 DOI: 10.1128/mbio.01443-18] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Klebsiella pneumoniae is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic heterogeneity of K. pneumoniae isolates complicates our ability to understand the virulence of K. pneumoniae. Characterization of virulence factors conserved between strains as well as strain-specific factors will improve our understanding of this important pathogen. The MarR family of regulatory proteins is widely distributed in bacteria and regulates cellular processes such as antibiotic resistance and the expression of virulence factors. Klebsiella encodes numerous MarR-like proteins, and they likely contribute to the ability of K. pneumoniae to respond to and survive under a wide variety of environmental conditions, including those present in the human body. We tested loss-of-function mutations in all the marR homologues in a murine pneumonia model and found that two (kvrA and kvrB) significantly impacted the virulence of K1 and K2 capsule type hypervirulent (hv) strains and that kvrA affected the virulence of a sequence type 258 (ST258) classical strain. In the hv strains, kvrA and kvrB mutants displayed phenotypes associated with reduced capsule production, mucoviscosity, and transcription from galF and manC promoters that drive expression of capsule synthesis genes. In contrast, kvrA and kvrB mutants in the ST258 strain had no effect on capsule gene expression or capsule-related phenotypes. Thus, KvrA and KvrB affect virulence in classical and hv strains but the effect on virulence may not be exclusively due to effects on capsule production. In addition to having a reputation as the causative agent for hospital-acquired infections as well as community-acquired invasive infections, Klebsiella pneumoniae has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. Due to the rapid emergence of carbapenem resistance among K. pneumoniae strains, a better understanding of virulence mechanisms and identification of new potential drug targets are needed. This study identified two novel regulators (KvrA and KvrB) of virulence in K. pneumoniae and demonstrated that their effect on virulence in invasive strains is likely due in part to effects on capsule production (a major virulence determinant) and hypermucoviscosity. KvrA also impacts the virulence of classical strains but does not appear to affect capsule gene expression in this strain. KvrA and KvrB are conserved among K. pneumoniae strains and thus could regulate capsule expression and virulence in diverse strains regardless of capsule type.
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17
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Ren YA, Gao H, Ouyang X. Advances in DNA Origami Nanopores: Fabrication, Characterization and Applications. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800173] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Yong-An Ren
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Key Laboratory of Modern Separation Science in Shaanxi Province, College of Chemistry & Material Science; Northwest University; Xi'an Shaanxi 710127 China
| | - Han Gao
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Key Laboratory of Modern Separation Science in Shaanxi Province, College of Chemistry & Material Science; Northwest University; Xi'an Shaanxi 710127 China
| | - Xiangyuan Ouyang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education of China, Key Laboratory of Modern Separation Science in Shaanxi Province, College of Chemistry & Material Science; Northwest University; Xi'an Shaanxi 710127 China
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18
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Liu Y, Liu Q, Qi L, Ding T, Wang Z, Fu J, Hu M, Li M, Song J, Liu X. Temporal Regulation of a Salmonella Typhimurium Virulence Factor by the Transcriptional Regulator YdcR. Mol Cell Proteomics 2017; 16:1683-1693. [PMID: 28674150 DOI: 10.1074/mcp.m117.068296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 06/08/2017] [Indexed: 11/06/2022] Open
Abstract
We previously examined Salmonella proteome within infected host cells and found differential expression of many proteins with defined functional roles such as metabolism or virulence. However, the precise roles of other altered proteins in Salmonella pathogenesis are largely unknown. A putative transcriptional regulator, YdcR, was highly induced intracellularly whereas barely expressed in vitro, implicating potential relevance to bacterial infection. To unveil its physiological functions, we exploited quantitative proteomics of intracellular Salmonella and found that genetic ablation of ydcR resulted in severe repression of SrfN, a known virulence factor. Immunoblotting, qRT-PCR, and β-galactosidase assays further demonstrate YdcR-dependent transcription and expression of srfN Moreover, we found physical interaction of YdcR with the promoter region of srfN, suggesting direct activation of its transcription. Importantly, a Salmonella mutant lacking ydcR was markedly attenuated in a mouse model of infection. Our findings reveal that YdcR temporally regulates the virulence factor SrfN during infection, thus contributing to Salmonella pathogenesis. Our work also highlights the utility of combining quantitative proteomics and bacterial genetics for uncovering the functional roles of transcription factors and likely other uncharacterized proteins as well.
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Affiliation(s)
- Yanhua Liu
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Qian Liu
- §Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
| | - Linlu Qi
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Tao Ding
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Zhen Wang
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jiaqi Fu
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Mo Hu
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Min Li
- §Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
| | - Jeongmin Song
- ¶Department of Microbiology & Immunology, Cornell University, Ithaca, New York 14853-6401
| | - Xiaoyun Liu
- From the ‡Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China;
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19
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Curran TD, Abacha F, Hibberd SP, Rolfe MD, Lacey MM, Green J. Identification of new members of the Escherichia coli K-12 MG1655 SlyA regulon. MICROBIOLOGY-SGM 2017; 163:400-409. [PMID: 28073397 PMCID: PMC5797941 DOI: 10.1099/mic.0.000423] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
SlyA is a member of the MarR family of bacterial transcriptional regulators. Previously, SlyA has been shown to directly regulate only two operons in Escherichia coli K-12 MG1655, fimB and hlyE (clyA). In both cases, SlyA activates gene expression by antagonizing repression by the nucleoid-associated protein H-NS. Here, the transcript profiles of aerobic glucose-limited steady-state chemostat cultures of E. coli K-12 MG1655, slyA mutant and slyA over-expression strains are reported. The transcript profile of the slyA mutant was not significantly different from that of the parent; however, that of the slyA expression strain was significantly different from that of the vector control. Transcripts representing 27 operons were increased in abundance, whereas 3 were decreased. Of the 30 differentially regulated operons, 24 have previously been associated with sites of H-NS binding, suggesting that antagonism of H-NS repression is a common feature of SlyA-mediated transcription regulation. Direct binding of SlyA to DNA located upstream of a selection of these targets permitted the identification of new operons likely to be directly regulated by SlyA. Transcripts of four operons coding for cryptic adhesins exhibited enhanced expression, and this was consistent with enhanced biofilm formation associated with the SlyA over-producing strain.
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Affiliation(s)
- Thomas D Curran
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Fatima Abacha
- Biomolecular Research Centre, Sheffield Hallam University, Sheffield, S1 1WB, UK
| | - Stephen P Hibberd
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Matthew D Rolfe
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Melissa M Lacey
- Biomolecular Research Centre, Sheffield Hallam University, Sheffield, S1 1WB, UK
| | - Jeffrey Green
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
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Affiliation(s)
- Wenqing Shi
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Alicia K. Friedman
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Lane A. Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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21
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Zhou J, Zhang H, Lv M, Chen Y, Liao L, Cheng Y, Liu S, Chen S, He F, Cui Z, Jiang Z, Chang C, Zhang L. SlyA regulates phytotoxin production and virulence in Dickeya zeae EC1. MOLECULAR PLANT PATHOLOGY 2016; 17:1398-1408. [PMID: 26814706 PMCID: PMC6638372 DOI: 10.1111/mpp.12376] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 01/23/2016] [Accepted: 01/24/2016] [Indexed: 06/05/2023]
Abstract
Dickeya zeae is a causal agent of rice root rot disease. The pathogen is known to produce a range of virulence factors, including phytotoxic zeamines and extracellular enzymes, but the mechanisms of virulence regulation remain vague. In this study, we identified a SlyA/MarR family transcription factor SlyA in D. zeae strain EC1. Disruption of slyA significantly decreased zeamine production, enhanced swimming and swarming motility, reduced biofilm formation and significantly decreased pathogenicity on rice. Quantitative polymerase chain reaction (qPCR) analysis confirmed the role of SlyA in transcriptional modulation of a range of genes associated with bacterial virulence. In trans expression of slyA in expI mutants recovered the phenotypes of motility and biofilm formation, suggesting that SlyA is downstream of the acylhomoserine lactone-mediated quorum sensing pathway. Taken together, the findings from this study unveil a key transcriptional regulatory factor involved in the modulation of virulence factor production and overall pathogenicity of D. zeae EC1.
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Affiliation(s)
- Jia‐Nuan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Hai‐Bao Zhang
- Institute of Molecular and Cell Biology 61 Biopolis DriveSingapore138673
| | - Ming‐Fa Lv
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Yu‐Fan Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Li‐Sheng Liao
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Ying‐Ying Cheng
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Shi‐Yin Liu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Shao‐Hua Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Fei He
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Zi‐Ning Cui
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Zi‐De Jiang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Chang‐Qing Chang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
| | - Lian‐Hui Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant PathologySouth China Agricultural UniversityGuangzhou510642China
- Institute of Molecular and Cell Biology 61 Biopolis DriveSingapore138673
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22
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Gao D, Li Y, Xu Z, Sheng A, Zheng E, Shao Z, Liu N, Lu C. The role of regulator Eha in Edwardsiella tarda pathogenesis and virulence gene transcription. Microb Pathog 2016; 95:216-223. [DOI: 10.1016/j.micpath.2016.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 03/20/2016] [Accepted: 03/22/2016] [Indexed: 11/29/2022]
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Abstract
Cationic antimicrobial peptides (CAMPs) are important innate immune defenses that inhibit colonization by pathogens and contribute to clearance of infections. Gram-negative bacterial pathogens are a major target, yet many of them have evolved mechanisms to resist these antimicrobials. These resistance mechanisms can be critical contributors to bacterial virulence and are often crucial for survival within the host. Here, we summarize methods used by Gram-negative bacteria to resist CAMPs. Understanding these mechanisms may lead to new therapeutic strategies against pathogens with extensive CAMP resistance.
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Affiliation(s)
- Victor I. Band
- Department of Microbiology and Immunology, Emory University, Atlanta, GA 30329, USA; E-Mail:
- Yerkes Primate Research Center, Emory University, Atlanta, GA 30329, USA
- Emory Vaccine Center, Emory University, Atlanta, GA 30329, USA
| | - David S. Weiss
- Yerkes Primate Research Center, Emory University, Atlanta, GA 30329, USA
- Emory Vaccine Center, Emory University, Atlanta, GA 30329, USA
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30329, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-404-727-8214; Fax: +1-404-727-8199
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Characterization of SlyA in Shigella flexneri Identifies a Novel Role in Virulence. Infect Immun 2016; 84:1073-1082. [PMID: 26831468 DOI: 10.1128/iai.00806-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/23/2016] [Indexed: 12/18/2022] Open
Abstract
The SlyA transcriptional regulator has important roles in the virulence and pathogenesis of several members of the Enterobacteriaceae family, including Salmonella enterica serovar Typhimurium and Escherichia coli. Despite the identification of the slyA gene in Shigella flexneri nearly 2 decades ago, as well as the significant conservation of SlyA among enteric bacteria, the role of SlyA in Shigella remains unknown. The genes regulated by SlyA in closely related organisms often are absent from or mutated inS. flexneri, and consequently many described SlyA-dependent phenotypes are not present. By characterizing the expression of slyA and determining its ultimate effect in this highly virulent organism, we postulated that novel SlyA-regulated virulence phenotypes would be identified. In this study, we report the first analysis of SlyA in Shigella and show that (i) the slyA gene is transcribed and ultimately translated into protein, (ii) slyA promoter activity is maximal during stationary phase and is negatively autoregulated and positively regulated by the PhoP response regulator, (iii) the exogenous expression of slyA rescues transcription and virulence-associated deficiencies during virulence-repressed conditions, and (iv) the absence of slyA significantly decreases acid resistance, demonstrating a novel and important role in Shigella virulence. Cumulatively, our study illustrates unexpected parallels between the less conserved S. flexneri and S Typhimurium slyA promoters as well as a unique role for SlyA in Shigella virulence that has not been described previously in any closely related organism.
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25
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Powell DA, Roberts LM, Ledvina HE, Sempowski GD, Curtiss R, Frelinger JA. Distinct innate responses are induced by attenuated Salmonella enterica serovar Typhimurium mutants. Cell Immunol 2015; 299:42-9. [PMID: 26546408 DOI: 10.1016/j.cellimm.2015.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/09/2015] [Accepted: 10/13/2015] [Indexed: 02/04/2023]
Abstract
Upon bacterial infection the host cells generate a wide variety of cytokines. Genetic attenuation of bacterial physiological pathogens can be accomplished not only by disruption of normal bacterial processes, but also by the loss of the ability to redirect the host immune system. We examined nine attenuated Salmonella Typhimurium mutants for their ability to replicate as well as the cytokines produced after infection of Bone Marrow Derived Macrophages (BMDM). Infection of BMDM with attenuated Salmonella mutants led to host cytokine patterns distinct from those that followed WT infection. Surprisingly, each bacterial mutant had a unique cytokine signature. Because some of the mutants induced an IL-10 response not seen in WT, we examined the role of IL-10 on Salmonella replication. Surprisingly, addition of IL-10 before or concurrent with infection restricted growth of WT Salmonella in BMDM. Bacterial attenuation is not a single process and results in attenuated host responses, which result in unique patterns for each attenuated mutants.
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Affiliation(s)
- Daniel A Powell
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States.
| | - Lydia M Roberts
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
| | - Hannah E Ledvina
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
| | | | - Roy Curtiss
- Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85281, United States
| | - Jeffrey A Frelinger
- Department of Immunobiology, University of Arizona, Tucson, AZ 85719, United States
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26
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Tang T, Gao Q, Barrow P, Wang M, Cheng A, Jia R, Zhu D, Chen S, Liu M, Sun K, Yang Q, Chen X. Development and evaluation of live attenuated Salmonella vaccines in newly hatched duckings. Vaccine 2015; 33:5564-5571. [DOI: 10.1016/j.vaccine.2015.09.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 08/28/2015] [Accepted: 09/04/2015] [Indexed: 10/23/2022]
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27
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Erhardt M, Dersch P. Regulatory principles governing Salmonella and Yersinia virulence. Front Microbiol 2015; 6:949. [PMID: 26441883 PMCID: PMC4563271 DOI: 10.3389/fmicb.2015.00949] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/27/2015] [Indexed: 11/13/2022] Open
Abstract
Enteric pathogens such as Salmonella and Yersinia evolved numerous strategies to survive and proliferate in different environmental reservoirs and mammalian hosts. Deciphering common and pathogen-specific principles for how these bacteria adjust and coordinate spatiotemporal expression of virulence determinants, stress adaptation, and metabolic functions is fundamental to understand microbial pathogenesis. In order to manage sudden environmental changes, attacks by the host immune systems and microbial competition, the pathogens employ a plethora of transcriptional and post-transcriptional control elements, including transcription factors, sensory and regulatory RNAs, RNAses, and proteases, to fine-tune and control complex gene regulatory networks. Many of the contributing global regulators and the molecular mechanisms of regulation are frequently conserved between Yersinia and Salmonella. However, the interplay, arrangement, and composition of the control elements vary between these closely related enteric pathogens, which generate phenotypic differences leading to distinct pathogenic properties. In this overview we present common and different regulatory networks used by Salmonella and Yersinia to coordinate the expression of crucial motility, cell adhesion and invasion determinants, immune defense strategies, and metabolic adaptation processes. We highlight evolutionary changes of the gene regulatory circuits that result in different properties of the regulatory elements and how this influences the overall outcome of the infection process.
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Affiliation(s)
- Marc Erhardt
- Young Investigator Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research Braunschweig, Germany
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28
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Deditius JA, Felgner S, Spöring I, Kühne C, Frahm M, Rohde M, Weiß S, Erhardt M. Characterization of Novel Factors Involved in Swimming and Swarming Motility in Salmonella enterica Serovar Typhimurium. PLoS One 2015; 10:e0135351. [PMID: 26267246 PMCID: PMC4534456 DOI: 10.1371/journal.pone.0135351] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/21/2015] [Indexed: 12/16/2022] Open
Abstract
Salmonella enterica utilizes flagellar motility to swim through liquid environments and on surfaces. The biosynthesis of the flagellum is regulated on various levels, including transcriptional and posttranscriptional mechanisms. Here, we investigated the motility phenotype of 24 selected single gene deletions that were previously described to display swimming and swarming motility effects. Mutations in flgE, fliH, ydiV, rfaG, yjcC, STM1267 and STM3363 showed an altered motility phenotype. Deletions of flgE and fliH displayed a non-motile phenotype in both swimming and swarming motility assays as expected. The deletions of STM1267, STM3363, ydiV, rfaG and yjcC were further analyzed in detail for flagellar and fimbrial gene expression and filament formation. A ΔydiV mutant showed increased swimming motility, but a decrease in swarming motility, which coincided with derepression of curli fimbriae. A deletion of yjcC, encoding for an EAL domain-containing protein, increased swimming motility independent on flagellar gene expression. A ΔSTM1267 mutant displayed a hypermotile phenotype on swarm agar plates and was found to have increased numbers of flagella. In contrast, a knockout of STM3363 did also display an increase in swarming motility, but did not alter flagella numbers. Finally, a deletion of the LPS biosynthesis-related protein RfaG reduced swimming and swarming motility, associated with a decrease in transcription from flagellar class II and class III promoters and a lack of flagellar filaments.
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Affiliation(s)
- Julia Andrea Deditius
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Sebastian Felgner
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Imke Spöring
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Caroline Kühne
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Michael Frahm
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Siegfried Weiß
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Marc Erhardt
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
- * E-mail:
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29
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Wang D, Guo C, Gu L, Zhang X. Comparative study of the marR genes within the family Enterobacteriaceae. J Microbiol 2014; 52:452-9. [PMID: 24723108 DOI: 10.1007/s12275-014-3586-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/11/2013] [Accepted: 12/30/2013] [Indexed: 01/22/2023]
Abstract
marR genes are members of an ancient family originally identified in Escherichia coli. This family is widely distributed in archaea and bacteria. Homologues of this family have a conserved winged helix fold. MarR proteins are involved in non-specific resistance systems conferring resistance to multiple antibiotics. Extensive studies have shown the importance of MarR proteins in physiology and pathogenicity in Enterobacteria, but little is known about their origin or evolution. In this study, all the marR genes in 43 enterobacterial genomes representing 14 genera were identified, and the phylogenetic relationships and genetic parameters were analyzed. Several major findings were made. Three conserved marR genes originated earlier than Enterobacteriaceae and a geneloss event was found to have taken place in Yersinia pestis Antiqua. Three functional genes, rovA, hor, and slyA, were found to be clear orthologs among Enterobacteriaceae. The copy number of marR genes in Enterobacteriaceae was found to vary from 2 to 11. These marR genes exhibited a faster rate of nucleotide substitution than housekeeping genes did. Specifically, the regions of marR domain were found to be subject to strong purifying selection. The phylogenetic relationship and genetic parameter analyses were consistent with conservation and specificity of marR genes. These dual characters helped MarR to maintain a conserved binding motif and variable C-terminus, which are important to adaptive responses to a number of external stimuli in Enterobacteriaceae.
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Affiliation(s)
- Dan Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, 210093, Nanjing, P. R. China
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30
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Gao D, Cheng J, Zheng E, Li Y, Shao Z, Xu Z, Lu C. Eha, a transcriptional regulator of hemolytic activity ofEdwardsiella tarda. FEMS Microbiol Lett 2014; 353:132-40. [DOI: 10.1111/1574-6968.12420] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/02/2014] [Accepted: 03/07/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Daqing Gao
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Jing Cheng
- JiangSu University School of Medicine; Zhenjiang China
| | - Enjin Zheng
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Yuhong Li
- Department of Pathogenic Microbiology and Immunology; Southeast University School of Medicine; Nanjing China
| | - Zeye Shao
- Department of Clinical Lab; Southeast University School of Medicine; Nanjing China
| | - Zeyan Xu
- JiangSu University School of Medicine; Zhenjiang China
| | - Chengping Lu
- NanJing Agricultural University, College of Veterinary Medicine; Nanjing China
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Foley SL, Johnson TJ, Ricke SC, Nayak R, Danzeisen J. Salmonella pathogenicity and host adaptation in chicken-associated serovars. Microbiol Mol Biol Rev 2013; 77:582-607. [PMID: 24296573 PMCID: PMC3973385 DOI: 10.1128/mmbr.00015-13] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Enteric pathogens such as Salmonella enterica cause significant morbidity and mortality. S. enterica serovars are a diverse group of pathogens that have evolved to survive in a wide range of environments and across multiple hosts. S. enterica serovars such as S. Typhi, S. Dublin, and S. Gallinarum have a restricted host range, in which they are typically associated with one or a few host species, while S. Enteritidis and S. Typhimurium have broad host ranges. This review examines how S. enterica has evolved through adaptation to different host environments, especially as related to the chicken host, and continues to be an important human pathogen. Several factors impact host range, and these include the acquisition of genes via horizontal gene transfer with plasmids, transposons, and phages, which can potentially expand host range, and the loss of genes or their function, which would reduce the range of hosts that the organism can infect. S. Gallinarum, with a limited host range, has a large number of pseudogenes in its genome compared to broader-host-range serovars. S. enterica serovars such as S. Kentucky and S. Heidelberg also often have plasmids that may help them colonize poultry more efficiently. The ability to colonize different hosts also involves interactions with the host's immune system and commensal organisms that are present. Thus, the factors that impact the ability of Salmonella to colonize a particular host species, such as chickens, are complex and multifactorial, involving the host, the pathogen, and extrinsic pressures. It is the interplay of these factors which leads to the differences in host ranges that we observe today.
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Salmonella enterica serovar Typhimurium skills to succeed in the host: virulence and regulation. Clin Microbiol Rev 2013; 26:308-41. [PMID: 23554419 DOI: 10.1128/cmr.00066-12] [Citation(s) in RCA: 498] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is a primary enteric pathogen infecting both humans and animals. Infection begins with the ingestion of contaminated food or water so that salmonellae reach the intestinal epithelium and trigger gastrointestinal disease. In some patients the infection spreads upon invasion of the intestinal epithelium, internalization within phagocytes, and subsequent dissemination. In that case, antimicrobial therapy, based on fluoroquinolones and expanded-spectrum cephalosporins as the current drugs of choice, is indicated. To accomplish the pathogenic process, the Salmonella chromosome comprises several virulence mechanisms. The most important virulence genes are those located within the so-called Salmonella pathogenicity islands (SPIs). Thus far, five SPIs have been reported to have a major contribution to pathogenesis. Nonetheless, further virulence traits, such as the pSLT virulence plasmid, adhesins, flagella, and biofilm-related proteins, also contribute to success within the host. Several regulatory mechanisms which synchronize all these elements in order to guarantee bacterial survival have been described. These mechanisms govern the transitions from the different pathogenic stages and drive the pathogen to achieve maximal efficiency inside the host. This review focuses primarily on the virulence armamentarium of this pathogen and the extremely complicated regulatory network controlling its success.
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RflM functions as a transcriptional repressor in the autogenous control of the Salmonella Flagellar master operon flhDC. J Bacteriol 2013; 195:4274-82. [PMID: 23873910 DOI: 10.1128/jb.00728-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Motility of bacteria like Salmonella enterica is a highly regulated process that responds to a variety of internal and external stimuli. A hierarchy of three promoter classes characterizes the Salmonella flagellar system, and the onset of flagellar gene expression depends on the oligomeric regulatory complex and class 1 gene product FlhD(4)C(2). The flhDC promoter is a target for a broad range of transcriptional regulators that bind within the flhDC promoter region and either negatively or positively regulate flhDC operon transcription. In this work, we demonstrate that the RflM protein is a key component of flhDC regulation. Transposon mutagenesis was performed to investigate a previously described autoinhibitory effect of the flagellar master regulatory complex FlhD(4)C(2). RflM is a LuxR homolog that functions as a flagellar class 1 transcriptional repressor. RflM was found to be the negative regulator of flhDC expression that is responsible for the formerly described autoinhibitory effect of the FlhD(4)C(2) complex on flhDC operon transcription (K. Kutsukake, Mol. Gen. Genet. 254:440-448, 1997). We conclude that upon commencement of flagellar gene expression, the FlhD(4)C(2) complex initiates a regulatory feedback loop by activating rflM gene expression. rflM encodes a transcriptional repressor, RflM, which fine-tunes flhDC expression levels.
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Product-mediated regulation of pentalenolactone biosynthesis in Streptomyces species by the MarR/SlyA family activators PenR and PntR. J Bacteriol 2013; 195:1255-66. [PMID: 23316039 DOI: 10.1128/jb.02079-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The orthologous penR and pntR genes from the pentalenolactone biosynthetic gene clusters of Streptomyces exfoliatus UC5319 and S. arenae TÜ469, respectively, were predicted to encode MarR/SlyA family transcriptional regulators, responsible for regulation of the biosynthesis of the sesquiterpenoid antibiotic pentalenolactone. The intrinsic target DNA sequences and small molecule ligands of purified recombinant PenR and PntR were identified by electrophoretic mobility shift assays. PenR bound to DNA from both the penR-gapN and penM-penH intergenic regions, while PntR bound only the corresponding pntR-gapR intergenic region. The targets of PenR and PntR were shown to be limited to conserved 37-bp DNA segments. Pentalenolactone and two late-stage biosynthetic intermediates, pentalenolactones D and F, act as ligands of both PenR and PntR, resulting in release of these proteins from their target DNA. The production of pentalenolactones was significantly decreased in the penR deletion mutant S. exfoliatus ΔpenR ZD27 but could be restored by complementation with either penR or pntR. Reverse transcription-PCR established that transcription of pentalenolactone biosynthetic and resistance genes decreased, while that of the penR gene itself increased in the penR deletion mutant S. exfoliatus ZD27 compared to the wild-type strain. The PenR protein thus serves as a positive regulator of pentalenolactone biosynthesis and self-resistance while acting as an autorepressor of penR.
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35
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Molecular basis of Yersinia enterocolitica temperature-dependent resistance to antimicrobial peptides. J Bacteriol 2012; 194:3173-88. [PMID: 22505678 DOI: 10.1128/jb.00308-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Antimicrobial peptides (APs) belong to the arsenal of weapons of the innate immune system against infections. In the case of gram-negative bacteria, APs interact with the anionic lipid A moiety of the lipopolysaccharide (LPS). In yersiniae most virulence factors are temperature regulated. Studies from our laboratory demonstrated that Yersinia enterocolitica is more susceptible to polymyxin B, a model AP, when grown at 37°C than at 22°C (J. A. Bengoechea, R. Díaz, and I. Moriyón, Infect. Immun. 64:4891-4899, 1996), and here we have extended this observation to other APs, not structurally related to polymyxin B. Mechanistically, we demonstrate that the lipid A modifications with aminoarabinose and palmitate are downregulated at 37°C and that they contribute to AP resistance together with the LPS O-polysaccharide. Bacterial loads of lipid A mutants in Peyer's patches, liver, and spleen of orogastrically infected mice were lower than those of the wild-type strain at 3 and 7 days postinfection. PhoPQ and PmrAB two-component systems govern the expression of the loci required to modify lipid A with aminoarabinose and palmitate, and their expressions are also temperature regulated. Our findings support the notion that the temperature-dependent regulation of loci controlling lipid A modifications could be explained by H-NS-dependent negative regulation alleviated by RovA. In turn, our data also demonstrate that PhoPQ and PmrAB regulate positively the expression of rovA, the effect of PhoPQ being more important. However, rovA expression reached wild-type levels in the phoPQ pmrAB mutant background, hence indicating the existence of an unknown regulatory network controlling rovA expression in this background.
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36
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Abstract
During stress, bacteria undergo extensive physiological transformations, many of which are coordinated by ppGpp. Although ppGpp is best known for enhancing cellular resilience by redirecting the RNA polymerase (RNAP) to certain genes, it also acts as a signal in many other cellular processes in bacteria. After a brief overview of ppGpp biosynthesis and its impact on promoter selection by RNAP, we discuss how bacteria exploit ppGpp to modulate the synthesis, stability or activity of proteins or regulatory RNAs that are crucial in challenging environments, using mechanisms beyond the direct regulation of RNAP activity.
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37
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Haneda T, Okada N, Kikuchi Y, Takagi M, Kurotaki T, Miki T, Arai S, Danbara H. Evaluation of Salmonella enterica serovar Typhimurium and Choleraesuis slyA mutant strains for use in live attenuated oral vaccines. Comp Immunol Microbiol Infect Dis 2011; 34:399-409. [DOI: 10.1016/j.cimid.2011.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 07/05/2011] [Accepted: 07/19/2011] [Indexed: 01/19/2023]
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38
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Dolan KT, Duguid EM, He C. Crystal structures of SlyA protein, a master virulence regulator of Salmonella, in free and DNA-bound states. J Biol Chem 2011; 286:22178-85. [PMID: 21550983 PMCID: PMC3121362 DOI: 10.1074/jbc.m111.245258] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 04/19/2011] [Indexed: 11/06/2022] Open
Abstract
SlyA is a master virulence regulator that controls the transcription of numerous genes in Salmonella enterica. We present here crystal structures of SlyA by itself and bound to a high-affinity DNA operator sequence in the slyA gene. SlyA interacts with DNA through direct recognition of a guanine base by Arg-65, as well as interactions between conserved Arg-86 and the minor groove and a large network of non-base-specific contacts with the sugar phosphate backbone. Our structures, together with an unpublished structure of SlyA bound to the small molecule effector salicylate (Protein Data Bank code 3DEU), reveal that, unlike many other MarR family proteins, SlyA dissociates from DNA without large conformational changes when bound to this effector. We propose that SlyA and other MarR global regulators rely more on indirect readout of DNA sequence to exert control over many genes, in contrast to proteins (such as OhrR) that recognize a single operator.
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Affiliation(s)
- Kyle T. Dolan
- From the Departments of Biochemistry and Molecular Biology and
- Chemistry and
- the Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637
| | - Erica M. Duguid
- From the Departments of Biochemistry and Molecular Biology and
| | - Chuan He
- Chemistry and
- the Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637
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39
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Barrow PA, Neto OCF. Pullorum disease and fowl typhoid—new thoughts on old diseases: a review. Avian Pathol 2011; 40:1-13. [DOI: 10.1080/03079457.2010.542575] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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40
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Quantitative PCR-based competitive index for high-throughput screening of Salmonella virulence factors. Infect Immun 2010; 79:360-8. [PMID: 21041489 DOI: 10.1128/iai.00873-10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is an intracellular pathogen and a main cause of food-borne illness. In this study, a quantitative PCR (qPCR)-based competitive index (CI) method was developed to simultaneously compare the growth of multiple Salmonella strains. This method was applied to a mixture of 17 Salmonella mutants lacking regulator genes, and their survival ratios were compared based on expression of natural resistance-associated macrophage protein 1 (Nramp1). Nramp1, as a major host innate immune component, controls the intracellular replication of pathogens. Deletion strains containing unique DNA barcodes in place of regulator genes were mixed with the parental control, and the bacteria were inoculated into congenic mice differing only at Nramp1. Most of the deletion strains were outcompeted by wild-type bacteria in either mouse strain, and the lack of Nramp1 didn't increase the tested strain/parent control replication ratios. When the same collection of mutants was tested in congenic mouse-derived primary macrophages, a major Nramp1-expressing cell type, six strains (ΔhimD, ΔphoP/phoQ, ΔrpoE, ΔrpoS, ΔompR/envZ, and Δhfq strains) grew better in Nramp1(-/-) than in Nramp1(+/+) macrophages, suggesting that these six regulators may play roles in overcoming Nramp1-mediated bactericidal activity in primary macrophages. The discrepancy in survival of macrophages and that of mice suggests either that there are differences in macrophage populations or that other cell types expressing Nramp1 control Salmonella proliferation in the host. The method described allows competitive infection analysis to be carried out on complex mixtures of bacteria and provides high reproducibility from independent biological replicates.
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Reverchon S, Van Gijsegem F, Effantin G, Zghidi-Abouzid O, Nasser W. Systematic targeted mutagenesis of the MarR/SlyA family members of Dickeya dadantii 3937 reveals a role for MfbR in the modulation of virulence gene expression in response to acidic pH. Mol Microbiol 2010; 78:1018-37. [PMID: 21062374 DOI: 10.1111/j.1365-2958.2010.07388.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pathogenicity of Dickeya dadantii is a process involving several factors, such as plant cell wall-degrading enzymes and adaptation systems to adverse conditions encountered in the apoplast. Regulators of the MarR family control a variety of biological processes, including adaptation to hostile environments and virulence. Analysis of the members of this family in D. dadantii led to the identification of a new regulator, MfbR, which controls virulence. MfbR represses its own expression but activates genes encoding plant cell wall-degrading enzymes. Purified MfbR increases the binding of RNA polymerase at the virulence gene promoters and inhibits transcription initiation at the mfbR promoter. MfbR activity appeared to be modulated by acidic pH, a stress encountered by pathogens during the early stages of infection. Expression of mfbR and its targets, during infection, showed that MfbR is unable to activate virulence genes in acidic conditions at an early step of infection. In contrast, alkalinization of the apoplast, during an advanced stage of infection, led to the potentialization of MfbR activity resulting in plant cell wall degrading enzyme production. This report presents a new example of how pathogens adjust virulence-associated factors during the time-course of an infection.
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42
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Humanized nonobese diabetic-scid IL2rgammanull mice are susceptible to lethal Salmonella Typhi infection. Proc Natl Acad Sci U S A 2010; 107:15589-94. [PMID: 20713716 DOI: 10.1073/pnas.1005566107] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhi, the cause of typhoid fever, is host-adapted to humans and unable to cause disease in mice. Here, we show that S. Typhi can replicate in vivo in nonobese diabetic (NOD)-scid IL2rgamma(null) mice engrafted with human hematopoietic stem cells (hu-SRC-SCID mice) to cause a lethal infection with pathological and inflammatory cytokine responses resembling human typhoid. In contrast, S. Typhi does not exhibit net replication or cause illness in nonengrafted or immunocompetent control animals. Screening of transposon pools in hu-SRC-SCID mice revealed both known and previously unknown Salmonella virulence determinants, including Salmonella Pathogenicity Islands 1, 2, 3, 4, and 6. Our observations indicate that the presence of human immune cells allows the in vivo replication of S. Typhi in mice. The hu-SRC-SCID mouse provides an unprecedented opportunity to gain insights into S. Typhi pathogenesis and devise strategies for the prevention of typhoid fever.
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43
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Andrews-Polymenis HL, Bäumler AJ, McCormick BA, Fang FC. Taming the elephant: Salmonella biology, pathogenesis, and prevention. Infect Immun 2010; 78:2356-69. [PMID: 20385760 PMCID: PMC2876576 DOI: 10.1128/iai.00096-10] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella infections continue to cause substantial morbidity and mortality throughout the world. However, recent discoveries and new paradigms promise to lead to novel strategies to diagnose, treat, and prevent Salmonella infections. This review provides an update of the Salmonella field based on oral presentations given at the recent 3rd ASM Conference on Salmonella: Biology, Pathogenesis and Prevention.
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Affiliation(s)
- Helene L. Andrews-Polymenis
- Department of Microbiology and Molecular Pathogenesis, Texas A&M University System Health Science Center, College Station, Texas, Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California, Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester, Massachusetts, Departments of Microbiology and Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Andreas J. Bäumler
- Department of Microbiology and Molecular Pathogenesis, Texas A&M University System Health Science Center, College Station, Texas, Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California, Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester, Massachusetts, Departments of Microbiology and Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Beth A. McCormick
- Department of Microbiology and Molecular Pathogenesis, Texas A&M University System Health Science Center, College Station, Texas, Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California, Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester, Massachusetts, Departments of Microbiology and Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington
| | - Ferric C. Fang
- Department of Microbiology and Molecular Pathogenesis, Texas A&M University System Health Science Center, College Station, Texas, Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California, Department of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester, Massachusetts, Departments of Microbiology and Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington
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Erhardt M, Hughes KT. C-ring requirement in flagellar type III secretion is bypassed by FlhDC upregulation. Mol Microbiol 2009; 75:376-93. [PMID: 19919668 DOI: 10.1111/j.1365-2958.2009.06973.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The cytoplasmic C-ring of the flagellum consists of FliG, FliM and FliN and acts as an affinity cup to localize secretion substrates for protein translocation via the flagellar-specific type III secretion system. Random T-POP transposon mutagenesis was employed to screen for insertion mutants that allowed flagellar type III secretion in the absence of the C-ring using the flagellar type III secretion system-specific hook-beta-lactamase reporter (Lee and Hughes, 2006). Any condition resulting in at least a twofold increase in flhDC expression was sufficient to overcome the requirement for the C-ring and the ATPase complex FliHIJ in flagellar type III secretion. Insertions in known and unknown flagellar regulatory loci were isolated as well as chromosomal duplications of the flhDC region. The twofold increased flhDC mRNA level coincided in a twofold increase in the number of hook-basal bodies per cell as analysed by fluorescent microscopy. These results indicate that the C-ring functions as a nonessential affinity cup-like structure during flagellar type III secretion to enhance the specificity and efficiency of the secretion process.
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Affiliation(s)
- Marc Erhardt
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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Short-term signatures of evolutionary change in the Salmonella enterica serovar typhimurium 14028 genome. J Bacteriol 2009; 192:560-7. [PMID: 19897643 DOI: 10.1128/jb.01233-09] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is a Gram-negative pathogen that causes gastroenteritis in humans and a typhoid-like disease in mice and is often used as a model for the disease promoted by the human-adapted S. enterica serovar Typhi. Despite its health importance, the only S. Typhimurium strain for which the complete genomic sequence has been determined is the avirulent LT2 strain, which is extensively used in genetic and physiologic studies. Here, we report the complete genomic sequence of the S. Typhimurium strain 14028s, as well as those of its progenitor and two additional derivatives. Comparison of these S. Typhimurium genomes revealed differences in the patterns of sequence evolution and the complete inventory of genetic alterations incurred in virulent and avirulent strains, as well as the sequence changes accumulated during laboratory passage of pathogenic organisms.
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Charles RC, Harris JB, Chase MR, Lebrun LM, Sheikh A, LaRocque RC, Logvinenko T, Rollins SM, Tarique A, Hohmann EL, Rosenberg I, Krastins B, Sarracino DA, Qadri F, Calderwood SB, Ryan ET. Comparative proteomic analysis of the PhoP regulon in Salmonella enterica serovar Typhi versus Typhimurium. PLoS One 2009; 4:e6994. [PMID: 19746165 PMCID: PMC2736619 DOI: 10.1371/journal.pone.0006994] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 07/24/2009] [Indexed: 12/20/2022] Open
Abstract
Background S. Typhi, a human-restricted Salmonella
enterica serovar, causes a systemic intracellular infection in
humans (typhoid fever). In comparison, S. Typhimurium
causes gastroenteritis in humans, but causes a systemic typhoidal illness in
mice. The PhoP regulon is a well studied two component (PhoP/Q) coordinately
regulated network of genes whose expression is required for intracellular
survival of S. enterica. Methodology/Principal Findings Using high performance liquid chromatography mass spectrometry (HPLC-MS/MS),
we examined the protein expression profiles of three sequenced S.
enterica strains: S. Typhimurium LT2,
S. Typhi CT18, and S. Typhi Ty2 in
PhoP-inducing and non-inducing conditions in vitro and
compared these results to profiles of
phoP−/Q−
mutants derived from S. Typhimurium LT2 and
S. Typhi Ty2. Our analysis identified 53 proteins in
S. Typhimurium LT2 and 56 proteins in
S. Typhi that were regulated in a PhoP-dependent manner. As
expected, many proteins identified in S. Typhi demonstrated
concordant differential expression with a homologous protein in
S. Typhimurium. However, three proteins (HlyE, STY1499, and
CdtB) had no homolog in S. Typhimurium. HlyE is a
pore-forming toxin. STY1499 encodes a stably expressed protein of unknown
function transcribed in the same operon as HlyE. CdtB is a cytolethal
distending toxin associated with DNA damage, cell cycle arrest, and cellular
distension. Gene expression studies confirmed up-regulation of mRNA of HlyE,
STY1499, and CdtB in S. Typhi in PhoP-inducing
conditions. Conclusions/Significance This study is the first protein expression study of the PhoP virulence
associated regulon using strains of Salmonella mutant in
PhoP, has identified three Typhi-unique proteins (CdtB, HlyE and STY1499)
that are not present in the genome of the wide host-range Typhimurium, and
includes the first protein expression profiling of a live attenuated
bacterial vaccine studied in humans (Ty800).
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Affiliation(s)
- Richelle C Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA.
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Chaudhuri RR, Peters SE, Pleasance SJ, Northen H, Willers C, Paterson GK, Cone DB, Allen AG, Owen PJ, Shalom G, Stekel DJ, Charles IG, Maskell DJ. Comprehensive identification of Salmonella enterica serovar typhimurium genes required for infection of BALB/c mice. PLoS Pathog 2009; 5:e1000529. [PMID: 19649318 PMCID: PMC2712085 DOI: 10.1371/journal.ppat.1000529] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 07/06/2009] [Indexed: 01/13/2023] Open
Abstract
Genes required for infection of mice by Salmonella Typhimurium can be identified by the interrogation of random transposon mutant libraries for mutants that cannot survive in vivo. Inactivation of such genes produces attenuated S. Typhimurium strains that have potential for use as live attenuated vaccines. A quantitative screen, Transposon Mediated Differential Hybridisation (TMDH), has been developed that identifies those members of a large library of transposon mutants that are attenuated. TMDH employs custom transposons with outward-facing T7 and SP6 promoters. Fluorescently-labelled transcripts from the promoters are hybridised to whole-genome tiling microarrays, to allow the position of the transposon insertions to be determined. Comparison of microarray data from the mutant library grown in vitro (input) with equivalent data produced after passage of the library through mice (output) enables an attenuation score to be determined for each transposon mutant. These scores are significantly correlated with bacterial counts obtained during infection of mice using mutants with individual defined deletions of the same genes. Defined deletion mutants of several novel targets identified in the TMDH screen are effective live vaccines.
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Affiliation(s)
- Roy R. Chaudhuri
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Sarah E. Peters
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Stephen J. Pleasance
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Helen Northen
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Chrissie Willers
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Gavin K. Paterson
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Danielle B. Cone
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | | | | | - Gil Shalom
- Arrow Therapeutics Ltd., London, United Kingdom
| | - Dov J. Stekel
- Centre for Systems Biology, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Ian G. Charles
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Duncan J. Maskell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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48
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SlyA, a MarR family transcriptional regulator, is essential for virulence in Dickeya dadantii 3937. J Bacteriol 2009; 191:5409-18. [PMID: 19542281 DOI: 10.1128/jb.00240-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
SlyA, a MarR family transcriptional regulator, controls an assortment of biological functions in several animal-pathogenic bacteria. In order to elucidate the functions of SlyA in the phytopathogen Dickeya dadantii (formerly Erwinia chrysanthemi) 3937, a slyA gene deletion mutant (denoted DeltaslyA) was constructed. The mutant exhibited increased sensitivity to sodium hypochlorite, the cationic antimicrobial peptide polymyxin B, and oxidative stress. The mutant showed reduced production of pectate lyase and exopolysaccharide and an inability to form a pellicle. The mutant lacking a functional slyA gene showed a significantly reduced ability to cause maceration of potato tubers. Accordingly, the mutant exhibited significantly reduced bacterial growth and failed to hyperinduce pectate lyase production in planta. Introduction of a plasmid containing slyA into the DeltaslyA mutant caused all of these phenotypes to recover to wild-type levels. These results suggest that SlyA plays an important role in virulence to plants by positively regulating the expression of multiple pathogenicity-related traits of D. dadantii 3937.
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49
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Yoon H, McDermott JE, Porwollik S, McClelland M, Heffron F. Coordinated regulation of virulence during systemic infection of Salmonella enterica serovar Typhimurium. PLoS Pathog 2009; 5:e1000306. [PMID: 19229334 PMCID: PMC2639726 DOI: 10.1371/journal.ppat.1000306] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 01/22/2009] [Indexed: 11/18/2022] Open
Abstract
To cause a systemic infection, Salmonella must respond to many environmental cues during mouse infection and express specific subsets of genes in a temporal and spatial manner, but the regulatory pathways are poorly established. To unravel how micro-environmental signals are processed and integrated into coordinated action, we constructed in-frame non-polar deletions of 83 regulators inferred to play a role in Salmonella enteriditis Typhimurium (STM) virulence and tested them in three virulence assays (intraperitoneal [i.p.], and intragastric [i.g.] infection in BALB/c mice, and persistence in 129X1/SvJ mice). Overall, 35 regulators were identified whose absence attenuated virulence in at least one assay, and of those, 14 regulators were required for systemic mouse infection, the most stringent virulence assay. As a first step towards understanding the interplay between a pathogen and its host from a systems biology standpoint, we focused on these 14 genes. Transcriptional profiles were obtained for deletions of each of these 14 regulators grown under four different environmental conditions. These results, as well as publicly available transcriptional profiles, were analyzed using both network inference and cluster analysis algorithms. The analysis predicts a regulatory network in which all 14 regulators control the same set of genes necessary for Salmonella to cause systemic infection. We tested the regulatory model by expressing a subset of the regulators in trans and monitoring transcription of 7 known virulence factors located within Salmonella pathogenicity island 2 (SPI-2). These experiments validated the regulatory model and showed that the response regulator SsrB and the MarR type regulator, SlyA, are the terminal regulators in a cascade that integrates multiple signals. Furthermore, experiments to demonstrate epistatic relationships showed that SsrB can replace SlyA and, in some cases, SlyA can replace SsrB for expression of SPI-2 encoded virulence factors.
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Affiliation(s)
- Hyunjin Yoon
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Jason E. McDermott
- Pacific Northwest National Laboratories, Richland, Washington, United States of America
| | - Steffen Porwollik
- The Sydney Kimmel Cancer Center, San Diego, California, United States of America
| | - Michael McClelland
- The Sydney Kimmel Cancer Center, San Diego, California, United States of America
| | - Fred Heffron
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
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50
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A dual-signal regulatory circuit activates transcription of a set of divergent operons in Salmonella typhimurium. Proc Natl Acad Sci U S A 2008; 105:20924-9. [PMID: 19091955 DOI: 10.1073/pnas.0807071106] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a molecular mechanism for signal transduction that activates transcription of the SlyA regulon in Salmonella typhimurium. We demonstrate that SlyA mediates transcriptional activation in response to guanosine tetraphosphate, ppGpp, according to the following observations: (i) in vivo transcription of SlyA-dependent genes is repressed when ppGpp is absent; this transcription can be restored by overproducing SlyA; (ii) in vivo dimerization and binding of SlyA to the target promoter are facilitated in the presence of ppGpp; and (iii) in vitro SlyA binding to the target promoter is enhanced when ppGpp is supplemented. Thus, ppGpp must be the cytoplasmic component that stimulates SlyA regulatory function by interacting directly with this regulator in Salmonella. This signaling domain, integrated by the PhoP/PhoQ 2-component system that activates slyA transcription by sensing Mg(2+), forms feedforward loops that regulate chromosomal loci identified through a motif search over the S. typhimurium genome. Many such loci are divergent operons, each formed by 2 neighboring genes in which transcription of these 2 loci proceeds in opposite directions. Both genes, however, are controlled by PhoP and SlyA through a single shared PhoP box and SlyA box present in their intergenic regions. A substitution in either box sequence causes a simultaneous cessation of transcription of a divergent operon, pagD-pagC, equivalent to the phenotype in a phoP or slyA mutant. We also identified several chromosomal loci that possess pagC-type genes without the cognate pagD-type genes. Therefore, our results provide a molecular basis for the understanding of SlyA-dependent phenotypes associated with Salmonella virulence.
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