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Quintero-Yanes A, Léger L, Collignon M, Mignon J, Mayard A, Michaux C, Hallez R. Regulation of potassium uptake in Caulobacter crescentus. J Bacteriol 2024; 206:e0010724. [PMID: 39133005 PMCID: PMC11411941 DOI: 10.1128/jb.00107-24] [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: 03/09/2024] [Accepted: 07/13/2024] [Indexed: 08/13/2024] Open
Abstract
Potassium (K+) is an essential physiological element determining membrane potential, intracellular pH, osmotic/turgor pressure, and protein synthesis in cells. Here, we describe the regulation of potassium uptake systems in the oligotrophic α-proteobacterium Caulobacter crescentus known as a model for asymmetric cell division. We show that C. crescentus can grow in concentrations from the micromolar to the millimolar range by mainly using two K+ transporters to maintain potassium homeostasis, the low-affinity Kup and the high-affinity Kdp uptake systems. When K+ is not limiting, we found that the kup gene is essential while kdp inactivation does not impact the growth. In contrast, kdp becomes critical but not essential and kup dispensable for growth in K+-limited environments. However, in the absence of kdp, mutations in kup were selected to improve growth in K+-depleted conditions, likely by increasing the affinity of Kup for K+. In addition, mutations in the KdpDE two-component system, which regulates kdpABCDE expression, suggest that the inner membrane sensor regulatory component KdpD mainly works as a phosphatase to limit the growth when cells reach late exponential phase. Our data therefore suggest that KdpE is phosphorylated by another non-cognate histidine kinase. On top of this, we determined the KdpE-dependent and independent K+ transcriptome. Together, our work illustrates how an oligotrophic bacterium responds to fluctuation in K+ availability.IMPORTANCEPotassium (K+) is a key metal ion involved in many essential cellular processes. Here, we show that the oligotroph Caulobacter crescentus can support growth at micromolar concentrations of K+ by mainly using two K+ uptake systems, the low-affinity Kup and the high-affinity Kdp. Using genome-wide approaches, we also determined the entire set of genes required for C. crescentus to survive at low K+ concentration as well as the full K+-dependent regulon. Finally, we found that the transcriptional regulation mediated by the KdpDE two-component system is unconventional since unlike Escherichia coli, the inner membrane sensor regulatory component KdpD seems to work rather as a phosphatase on the phosphorylated response regulator KdpE~P.
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Affiliation(s)
- Alex Quintero-Yanes
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Loïc Léger
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Madeline Collignon
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Julien Mignon
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, Namur Institute of Structured Matter (NISM), Namur Research Institute for Life Sciences (NARILIS), Universite de Namur, Namur, Belgium
| | - Aurélie Mayard
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Catherine Michaux
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, Namur Institute of Structured Matter (NISM), Namur Research Institute for Life Sciences (NARILIS), Universite de Namur, Namur, Belgium
| | - Régis Hallez
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
- WEL Research Institute, University of Namur, Namur, Belgium
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Hu J, Yao J, Lei C, Sun X. c-di-AMP accumulation impairs toxin expression of Bacillus anthracis by down-regulating potassium importers. Microbiol Spectr 2024; 12:e0378623. [PMID: 38899864 PMCID: PMC11302148 DOI: 10.1128/spectrum.03786-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 04/20/2024] [Indexed: 06/21/2024] Open
Abstract
The Gram-positive bacterium Bacillus anthracis is the causative agent of anthrax and a bioterrorism threat worldwide. As a crucial second messenger in many bacterial species, cyclic di-AMP (c-di-AMP) modulates various key processes for bacterial homeostasis and pathogenesis. Overaccumulation of c-di-AMP alters cellular growth and reduces anthrax toxin expression as well as virulence in Bacillus anthracis by unresolved underlying mechanisms. In this report, we discovered that c-di-AMP binds to a series of receptors involved in potassium uptake in B. anthracis. By analyzing Kdp and Ktr mutants for osmotic stress, gene expression, and anthrax toxin expression, we also showed that c-di-AMP inhibits Kdp operon expression through binding to the KdpD and ydaO riboswitch; up-regulating intracellular potassium promotes anthrax toxin expression in c-di-AMP accumulated B. anthracis. Decreased anthrax toxin expression at high c-di-AMP occurs through the inhibition of potassium uptake. Understanding the molecular basis of how potassium uptake affects anthrax toxin has the potential to provide new insight into the control of B. anthracis.IMPORTANCEThe bacterial second messenger cyclic di-AMP (c-di-AMP) is a conserved global regulator of potassium homeostasis. How c-di-AMP regulates bacterial virulence is unknown. With this study, we provide a link between potassium uptake and anthrax toxin expression in Bacillus anthracis. c-di-AMP accumulation might inhibit anthrax toxin expression by suppressing potassium uptake.
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Affiliation(s)
- Jia Hu
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Junmin Yao
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chengfeng Lei
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Xiulian Sun
- Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
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Rocha R, Jorge JMP, Teixeira-Duarte CM, Figueiredo-Costa IR, Cereija TB, Ferreira-Teixeira PF, Herzberg C, Stülke J, Morais-Cabral JH. c-di-AMP determines the hierarchical organization of bacterial RCK proteins. Proc Natl Acad Sci U S A 2024; 121:e2318666121. [PMID: 38652747 PMCID: PMC11067040 DOI: 10.1073/pnas.2318666121] [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: 10/25/2023] [Accepted: 03/13/2024] [Indexed: 04/25/2024] Open
Abstract
In bacteria, intracellular K+ is involved in the regulation of membrane potential, cytosolic pH, and cell turgor as well as in spore germination, environmental adaptation, cell-to-cell communication in biofilms, antibiotic sensitivity, and infectivity. The second messenger cyclic-di-AMP (c-di-AMP) has a central role in modulating the intracellular K+ concentration in many bacterial species, controlling transcription and function of K+ channels and transporters. However, our understanding of how this regulatory network responds to c-di-AMP remains poor. We used the RCK (Regulator of Conductance of K+) proteins that control the activity of Ktr channels in Bacillus subtilis as a model system to analyze the regulatory function of c-di-AMP with a combination of in vivo and in vitro functional and structural characterization. We determined that the two RCK proteins (KtrA and KtrC) are neither physiologically redundant or functionally equivalent. KtrC is the physiologically dominant RCK protein in the regulation of Ktr channel activity. In explaining this hierarchical organization, we found that, unlike KtrA, KtrC is very sensitive to c-di-AMP inactivation and lack of c-di-AMP regulation results in RCK protein toxicity, most likely due to unregulated K+ flux. We also found that KtrC can assemble with KtrA, conferring c-di-AMP regulation to the functional KtrA/KtrC heteromers and potentially compensating KtrA toxicity. Altogether, we propose that the central role of c-di-AMP in the control of the K+ machinery, by modulating protein levels through gene transcription and by regulating protein activity, has determined the evolutionary selection of KtrC as the dominant RCK protein, shaping the hierarchical organization of regulatory components of the K+ machinery.
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Affiliation(s)
- Rita Rocha
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | - João M. P. Jorge
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | - Celso M. Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
| | | | - Tatiana B. Cereija
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
| | | | - Christina Herzberg
- Department of General Microbiology, Institute for Microbiology and Genetics, Georg-August-University Göttingen, Göttingen37073, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute for Microbiology and Genetics, Georg-August-University Göttingen, Göttingen37073, Germany
| | - João H. Morais-Cabral
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto4200-135, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto4200-135, Portugal
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Wang XY, Li P, Du XJ, Wang S. Effect of glutathione-transport-related gene gsiD on desiccation tolerance of Cronobacter sakazakii and its related regulatory mechanism. Appl Environ Microbiol 2024; 90:e0156223. [PMID: 38289135 PMCID: PMC10880603 DOI: 10.1128/aem.01562-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/16/2023] [Indexed: 02/22/2024] Open
Abstract
The outstanding desiccation tolerance of Cronobacter sakazakii (C. sakazakii) enables long-term persistence in food products with low-water activity to increase the infection risk, especially in low-birth-weight, immuno-compromised neonates, and infants less than 4 weeks of age. In our previous study, the disruption of glutathione transport-related gene gsiD by transposon was found to significantly increase its inactivation rate under drying stress challenges. However, the mechanism underlying the association between glutathione transport and desiccation tolerance of C. sakazakii remains to be clarified. In this study, the mechanism underlying their association was investigated in detail by constructing the gsiD gene deletion mutant. gsiD gene deletion was found to cause the dysfunction of the glutathione transport system GsiABCD and the limitation of glutathione import. The resulting decrease in intracellular glutathione caused the decreased potassium ions uptake and increased potassium ions efflux, inhibited the proline synthesis process, limited extracellular glutathione utilization, increased oxidant stress, reduced biofilm formation, and increased outer membrane permeability, which may be the main reasons for the significant reduction of the desiccation tolerance of C. sakazakii.IMPORTANCEContributing to its superior environmental adaptability, Cronobacter sakazakii can survive under many abiotic stress conditions. The outstanding desiccation tolerance makes this species persist in low-water activity foods, which increases harm to humans. For decades, many studies have focused on the desiccation tolerance of C. sakazakii, but the existing research is still insufficient. Our study found that gsiD gene deletion inhibited glutathione uptake and further decreased intracellular glutathione content, causing a decrease in desiccation tolerance and biofilm formation and an increase in outer membrane permeability. Moreover, the expression level of relative genes verified that gsiD gene deletion made the mutant not conducive to surviving in dry conditions due to restricting potassium ions uptake and efflux, inhibiting the conversion of glutamate to compatible solute proline, and increasing the oxidative stress of C. sakazakii. The above results enrich our knowledge of the desiccation tolerance mechanism of C. sakazakii.
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Affiliation(s)
- Xiao-yi Wang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Ping Li
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Xin-jun Du
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Shuo Wang
- State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
- Tianjin Key Laboratory of Food Science and Health, College of Medicine, Nankai University, Tianjin, China
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5
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Merkushova AV, Shikov AE, Nizhnikov AA, Antonets KS. For Someone, You Are the Whole World: Host-Specificity of Salmonella enterica. Int J Mol Sci 2023; 24:13670. [PMID: 37761974 PMCID: PMC10530738 DOI: 10.3390/ijms241813670] [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: 08/08/2023] [Revised: 08/27/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023] Open
Abstract
Salmonella enterica is a bacterial pathogen known to cause gastrointestinal infections in diverse hosts, including humans and animals. Despite extensive knowledge of virulence mechanisms, understanding the factors driving host specificity remains limited. In this study, we performed a comprehensive pangenome-wide analysis of S. enterica to identify potential loci determining preference towards certain hosts. We used a dataset of high-quality genome assemblies grouped into 300 reference clusters with a special focus on four host groups: humans, pigs, cattle, and birds. The reconstructed pangenome was shown to be open and enriched with the accessory component implying high genetic diversity. Notably, phylogenetic inferences did not correspond to the distribution of affected hosts, as large compact phylogenetic groups were absent. By performing a pangenome-wide association study, we identified potential host specificity determinants. These included multiple genes encoding proteins involved in distinct infection stages, e.g., secretion systems, surface structures, transporters, transcription regulators, etc. We also identified antibiotic resistance loci in host-adapted strains. Functional annotation corroborated the results obtained with significant enrichments related to stress response, antibiotic resistance, ion transport, and surface or extracellular localization. We suggested categorizing the revealed specificity factors into three main groups: pathogenesis, resistance to antibiotics, and propagation of mobile genetic elements (MGEs).
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Affiliation(s)
- Anastasiya V. Merkushova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
| | - Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.V.M.); (A.E.S.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia
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6
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Zou R, Zhao L, Shen D, Wu Y. TrkA serves as a virulence modulator in Porphyromonas gingivalis by maintaining heme acquisition and pathogenesis. Front Cell Infect Microbiol 2022; 12:1012316. [PMID: 36405968 PMCID: PMC9666725 DOI: 10.3389/fcimb.2022.1012316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/12/2022] [Indexed: 01/25/2023] Open
Abstract
Periodontitis is an inflammatory disease of the supporting tissues of the teeth, with polymicrobial infection serving as the major pathogenic factor. As a periodontitis-related keystone pathogen, Porphyromonas gingivalis can orchestrate polymicrobial biofilm skewing into dysbiosis. Some metatranscriptomic studies have suggested that modulation of potassium ion uptake might serve as a signal enhancing microbiota nososymbiocity and periodontitis progression. Although the relationship between potassium transport and virulence has been elucidated in some bacteria, less is mentioned about the periodontitis-related pathogen. Herein, we centered on the virulence modulation potential of TrkA, the potassium uptake regulatory protein of P. gingivalis, and uncovered TrkA as the modulator in the heme acquisition process and in maintaining optimal pathogenicity in an experimental murine model of periodontitis. Hemagglutination and hemolytic activities were attenuated in the case of trkA gene loss, and the entire transcriptomic profiling revealed that the trkA gene can control the expression of genes in relation to electron transport chain activity and translation, as well as some transcriptional factors, including cdhR, the regulator of the heme uptake system hmuYR. Collectively, these results link the heme acquisition process to the potassium transporter, providing new insights into the role of potassium ion in P. gingivalis pathogenesis.
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Affiliation(s)
| | | | | | - Yafei Wu
- *Correspondence: Daonan Shen, ; Yafei Wu,
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7
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Transcriptome sequencing reveals the difference in the expression of biofilm and planktonic cells between two strains of Salmonella Typhimurium. Biofilm 2022; 4:100086. [PMID: 36254114 PMCID: PMC9568869 DOI: 10.1016/j.bioflm.2022.100086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/22/2022] Open
Abstract
Salmonela enterica serovar Typhimurium (S. Typhimurium) is a food-borne pathogen that can form biofilms to increase its resistance to the external environment. Through the detection of biofilm of several S. Typhimurium strains in this study, strain CDC3 with strong biofilm forming capacity and strain CVCC3384 with weak biofilm forming capacity were identified. The genes expressed in planktonic and biofilm cells of two S. Typhimurium strains were analysed by transcriptome sequencing. Results showed that the genes related to the signal transduction pathway were upregulated and genes related to motility were downregulated in strain CDC3. By comparing biofilms and planktonic cells of the two strains, we found that CDC3 regulates biofilm formation mainly through the two-component system kdpABC, while strain CVCC3384 does so mainly through motility and quorum sensing. This study revealed regulation mechanism of biofilms formation between different biofilm forming capacity strains, and provided a theoretical basis for subsequent research.
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8
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Barcenilla C, Álvarez-Ordóñez A, López M, Alvseike O, Prieto M. Microbiological Safety and Shelf-Life of Low-Salt Meat Products-A Review. Foods 2022; 11:2331. [PMID: 35954097 PMCID: PMC9367943 DOI: 10.3390/foods11152331] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Salt is widely employed in different foods, especially in meat products, due to its very diverse and extended functionality. However, the high intake of sodium chloride in human diet has been under consideration for the last years, because it is related to serious health problems. The meat-processing industry and research institutions are evaluating different strategies to overcome the elevated salt concentrations in products without a quality reduction. Several properties could be directly or indirectly affected by a sodium chloride decrease. Among them, microbial stability could be shifted towards pathogen growth, posing a serious public health threat. Nonetheless, the majority of the literature available focuses attention on the sensorial and technological challenges that salt reduction implies. Thereafter, the need to discuss the consequences for shelf-life and microbial safety should be considered. Hence, this review aims to merge all the available knowledge regarding salt reduction in meat products, providing an assessment on how to obtain low salt products that are sensorily accepted by the consumer, technologically feasible from the perspective of the industry, and, in particular, safe with respect to microbial stability.
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Affiliation(s)
- Coral Barcenilla
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, University of León, 24071 León, Spain
| | - Avelino Álvarez-Ordóñez
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, University of León, 24071 León, Spain
- Institute of Food Science and Technology, University of León, 24007 León, Spain
| | - Mercedes López
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, University of León, 24071 León, Spain
- Institute of Food Science and Technology, University of León, 24007 León, Spain
| | - Ole Alvseike
- Animalia—Norwegian Meat and Poultry Research Centre, NO-0513 Oslo, Norway
| | - Miguel Prieto
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, University of León, 24071 León, Spain
- Institute of Food Science and Technology, University of León, 24007 León, Spain
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9
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The PTS
Ntr
-KdpDE-KdpFABC Pathway Contributes to Low Potassium Stress Adaptation and Competitive Nodulation of Sinorhizobium fredii. mBio 2022; 13:e0372121. [PMID: 35491828 PMCID: PMC9239096 DOI: 10.1128/mbio.03721-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In all ecological niches, potassium is actively consumed by diverse prokaryotes and their interacting eukaryote hosts. It is only just emerging that potassium is a key player in host-pathogen interactions, and the role of potassium in mutualistic interactions remains largely unknown.
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Liu BB, Salam N, Narsing Rao MP, Cheng S, Xie YG, Wang LY, Zhang YR, Yu XY, Guo SX, Li WJ. Haloterrigena gelatinilytica sp. nov., a new extremely halophilic archaeon isolated from salt-lake. Arch Microbiol 2022; 204:176. [PMID: 35166931 DOI: 10.1007/s00203-022-02783-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 12/01/2022]
Abstract
Two extremely halophilic strains, designated SYSU A558-1T and SYSU A121-1, were isolated from a saline sediment sample collected from Aiding salt-lake, China. Cells of strains SYSU A558-1T and SYSU A121-1 were Gram-stain-negative, coccoid, and non-motile. The strains were aerobic and grew at NaCl concentration of 10-30% (optimum, 20-22%), at 20-55 °C (optimum, 37-42 °C) and at pH 6.5-8.5 (optimum, 7.0-8.0). Cells lysed in distilled water. The polar lipids were phosphatidyl choline, phosphatidylglycerol phosphate methyl ester, disulfated diglycosyl diether-1 and unidentified glycolipid. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the two strains SYSU A558-1T and SYSU A121-1 were closely related to the membranes of the genus Haloterrigena. Phylogenetic and phylogenomic trees of strains SYSU A558-1T and SYSU A121-1 demonstrated a robust clade with Haloterrigena turkmenica, Haloterrigena salifodinae and Haloterrigena salina. The genomic DNA G + C content of strains SYSU A558-1T and SYSU A121-1 were 65.8 and 65.0%, respectively. Phenotypic, phylogenetic, chemotaxonomic and genome analysis suggested that the two strains SYSU A558-1T and SYSU A121-1 represent a novel species of the genus Haloterrigena, for which the name Haloterrigena gelatinilytica sp. nov. is proposed. The type strain is SYSU A558-1T (= KCTC 4259T = CGMCC 1.15953T).
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Affiliation(s)
- Bing-Bing Liu
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China
| | - Nimaichand Salam
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China
| | - Manik Prabhu Narsing Rao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China
| | - Shuang Cheng
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China
| | - Yuan-Guo Xie
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China
| | - Lai-You Wang
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China
| | - Yuan-Ru Zhang
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China
| | - Xin-Yuan Yu
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China
| | - Shu-Xian Guo
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China.
| | - Wen-Jun Li
- Henan Key Laboratory of Industrial Microbial Resources and Fermentation Technology, College of Biological and Chemical Engineering, Nanyang Institute of Technology, Nanyang, 473004, People's Republic of China. .,State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China. .,State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, 830011, People's Republic of China.
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11
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Wang S, Sun L, Narsing Rao MP, Liu GH, Jin PJ, Dong ZY, Lian ZH, Hao XY, Zhang MY, Li WJ. Alteribacter salitolerans sp. nov., isolated from a saline-alkaline soil. Arch Microbiol 2021; 204:53. [PMID: 34936048 DOI: 10.1007/s00203-021-02640-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/12/2021] [Accepted: 10/14/2021] [Indexed: 11/25/2022]
Abstract
A Gram-positive strain APA H-16(1)T was isolated from a saline-alkali soil sample collected from Heilongjiang Province, China. Cells were rod shaped, non-motile, endospore forming, and aerobic. Growth occurred at 10-45 °C (optimum, 35 °C), pH 7.0-10.5 (optimum, pH 9.5), and could tolerate NaCl up to 15.0% (w/v). Strain showed low 16S rRNA gene sequence similarities with Alteribacter natronophilus (97.8%), Alteribacter aurantiacus (97.7%), and Alteribacter populi (97.1%). The cell wall peptidoglycan was meso-diaminopimelic acid. The predominant menaquinone was MK-7. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipids, unidentified phospholipid, and unidentified lipid. The major fatty acids were anteiso-C15:0, and iso-C15:0. The genomic G + C content was 45.1%. The average nucleotide identity and digital DNA-DNA hybridization values between strain APA H-16(1)T and the most closely related species were below the cut-off level (95-96%; 70%) for species delineation. Based on phenotypic, phylogenetic, chemotaxonomic, and genome comparison, strain APA H-16(1)T represents a novel species of the genus Alteribacter, for which the name Alteribacter salitolerans sp. nov. is proposed. The type strain is APA H-16(1)T (= KCTC 43228T = CICC 25092T).
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Affiliation(s)
- Shuang Wang
- Heilongjiang Acacemy of Black Soil Conservation & Utilization, Heilongjiang Academy of Agricultural Sciences, Harbin, People's Republic of China
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, People's Republic of China
| | - Lei Sun
- Heilongjiang Acacemy of Black Soil Conservation & Utilization, Heilongjiang Academy of Agricultural Sciences, Harbin, People's Republic of China.
| | - Manik Prabhu Narsing Rao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China
| | - Guo-Hong Liu
- Agricultural Bio-Resources Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, People's Republic of China
| | - Pin-Jiao Jin
- Heilongjiang Acacemy of Black Soil Conservation & Utilization, Heilongjiang Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Zhou-Yan Dong
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, 264003, People's Republic of China
| | - Zheng-Han Lian
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China
| | - Xiao-Yu Hao
- Heilongjiang Acacemy of Black Soil Conservation & Utilization, Heilongjiang Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Ming-Yi Zhang
- Heilongjiang Acacemy of Black Soil Conservation & Utilization, Heilongjiang Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Wen-Jun Li
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, People's Republic of China.
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, People's Republic of China.
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12
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Cholo MC, Matjokotja MT, Osman AG, Anderson R. Role of the kdpDE Regulatory Operon of Mycobacterium tuberculosis in Modulating Bacterial Growth in vitro. Front Genet 2021; 12:698875. [PMID: 34394188 PMCID: PMC8358298 DOI: 10.3389/fgene.2021.698875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/12/2021] [Indexed: 11/18/2022] Open
Abstract
Bacteria use K+-uptake transporters differentially for adaptation in varying growth conditions. In Mycobacterium tuberculosis, two K+-uptake systems, the Trk comprising the CeoB and CeoC proteins and the Kdp consisting of the two-component system (TCS), KdpDE and KdpFABC, have been characterized, but their selective utilization during bacterial growth has not been completely explored. In the current study, the roles of the M. tuberculosis KdpDE regulatory system alone and in association with the Trk transporters in bacterial growth were investigated by evaluating the growth of M. tuberculosis KdpDE-deletion and KdpDE/Trk (KT)-double knockout mutant strains in planktonic culture under standard growth conditions. The KT-double knockout mutant strain was first constructed using homologous recombination procedures and was evaluated together with the KdpDE-deletion mutant and the wild-type (WT) strains with respect to their rates of growth, K+-uptake efficiencies, and K+-transporter gene expression during planktonic growth. During growth at optimal K+ concentrations and pH levels, selective deletion of the TCS KdpDE (KdpDE-deletion mutant) led to attenuation of bacterial growth and an increase in bacterial K+-uptake efficiency, as well as dysregulated expression of the kdpFABC and trk genes. Deletion of both the KdpDE and the Trk systems (KT-double knockout) also led to severely attenuated bacterial growth, as well as an increase in bacterial K+-uptake efficiency. These results demonstrate that the KdpDE regulatory system plays a key role during bacterial growth by regulating K+ uptake via modulation of the expression and activities of both the KdpFABC and Trk systems and is important for bacterial growth possibly by preventing cytoplasmic K+ overload.
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Affiliation(s)
- Moloko C Cholo
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Maborwa T Matjokotja
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Ayman G Osman
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Ronald Anderson
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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13
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Abstract
Potassium is an essential mineral nutrient required by all living cells for normal physiological function. Therefore, maintaining intracellular potassium homeostasis during bacterial infection is a requirement for the survival of both host and pathogen. However, pathogenic bacteria require potassium transport to fulfill nutritional and chemiosmotic requirements, and potassium has been shown to directly modulate virulence gene expression, antimicrobial resistance, and biofilm formation. Host cells also require potassium to maintain fundamental biological processes, such as renal function, muscle contraction, and neuronal transmission; however, potassium flux also contributes to critical immunological and antimicrobial processes, such as cytokine production and inflammasome activation. Here, we review the role and regulation of potassium transport and signaling during infection in both mammalian and bacterial cells and highlight the importance of potassium to the success and survival of each organism.
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14
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Stautz J, Hellmich Y, Fuss MF, Silberberg JM, Devlin JR, Stockbridge RB, Hänelt I. Molecular Mechanisms for Bacterial Potassium Homeostasis. J Mol Biol 2021; 433:166968. [PMID: 33798529 DOI: 10.1016/j.jmb.2021.166968] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/11/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022]
Abstract
Potassium ion homeostasis is essential for bacterial survival, playing roles in osmoregulation, pH homeostasis, regulation of protein synthesis, enzyme activation, membrane potential adjustment and electrical signaling. To accomplish such diverse physiological tasks, it is not surprising that a single bacterium typically encodes several potassium uptake and release systems. To understand the role each individual protein fulfills and how these proteins work in concert, it is important to identify the molecular details of their function. One needs to understand whether the systems transport ions actively or passively, and what mechanisms or ligands lead to the activation or inactivation of individual systems. Combining mechanistic information with knowledge about the physiology under different stress situations, such as osmostress, pH stress or nutrient limitation, one can identify the task of each system and deduce how they are coordinated with each other. By reviewing the general principles of bacterial membrane physiology and describing the molecular architecture and function of several bacterial K+-transporting systems, we aim to provide a framework for microbiologists studying bacterial potassium homeostasis and the many K+-translocating systems that are still poorly understood.
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Affiliation(s)
- Janina Stautz
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Yvonne Hellmich
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Michael F Fuss
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jakob M Silberberg
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jason R Devlin
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Randy B Stockbridge
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States.
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.
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15
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Röder J, Felgner P, Hensel M. Comprehensive Single Cell Analyses of the Nutritional Environment of Intracellular Salmonella enterica. Front Cell Infect Microbiol 2021; 11:624650. [PMID: 33834004 PMCID: PMC8021861 DOI: 10.3389/fcimb.2021.624650] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/25/2021] [Indexed: 12/11/2022] Open
Abstract
The facultative intracellular pathogen Salmonella enterica Typhimurium (STM) resides in a specific membrane-bound compartment termed the Salmonella-containing vacuole (SCV). STM is able to obtain all nutrients required for rapid proliferation, although being separated from direct access to host cell metabolites. The formation of specific tubular membrane compartments, called Salmonella-induced filaments (SIFs) are known to provides bacterial nutrition by giving STM access to endocytosed material and enabling proliferation. Additionally, STM expresses a range of nutrient uptake system for growth in nutrient limited environments to overcome the nutrition depletion inside the host. By utilizing dual fluorescence reporters, we shed light on the nutritional environment of intracellular STM in various host cells and distinct intracellular niches. We showed that STM uses nutrients of the host cell and adapts uniquely to the different nutrient conditions. In addition, we provide further evidence for improved nutrient supply by SIF formation or presence in the cytosol of epithelial cells, and the correlation of nutrient supply to bacterial proliferation.
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Affiliation(s)
- Jennifer Röder
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Pascal Felgner
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs – Center of Cellular Nanoanalytics, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
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16
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Fernandes AS, Pombinho A, Teixeira-Duarte CM, Morais-Cabral JH, Harley CA. Fluorometric Liposome Screen for Inhibitors of a Physiologically Important Bacterial Ion Channel. Front Microbiol 2021; 12:603700. [PMID: 33732218 PMCID: PMC7956971 DOI: 10.3389/fmicb.2021.603700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 02/01/2021] [Indexed: 11/13/2022] Open
Abstract
The bacterial K+ homeostasis machinery is widely conserved across bacterial species, and different from that in animals. Dysfunction in components of the machinery has an impact on intracellular turgor, membrane potential, adaptation to changes in both extracellular pH and osmolarity, and in virulence. Using a fluorescence-based liposome flux assay, we have performed a high-throughput screen to identify novel inhibitors of the KtrAB ion channel complex from Bacillus subtilis, a component of the K+ homeostasis machinery that is also present in many bacterial pathogens. The screen identified 41 compounds that inhibited K+ flux and that clustered into eight chemical groups. Many of the identified inhibitors were found to target KtrAB with an in vitro potency in the low μM range. We investigated the mechanisms of inhibition and found that most molecules affected either the membrane component of the channel, KtrB alone or the full KtrAB complex without a preference for the functional conformation of the channel, thus broadening their inhibitory action. A urea derivative molecule that inhibited the membrane component of KtrAB affected cell viability in conditions in which KtrAB activity is essential. With this proof-of-concept study, we demonstrate that targeting components of the K+ homeostasis machinery has the potential as a new antibacterial strategy and that the fluorescence-based flux assay is a robust tool for screening chemical libraries.
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Affiliation(s)
- Andreia S Fernandes
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - António Pombinho
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Celso M Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Carol A Harley
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
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17
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Abundant Monovalent Ions as Environmental Signposts for Pathogens during Host Colonization. Infect Immun 2021; 89:IAI.00641-20. [PMID: 33526568 DOI: 10.1128/iai.00641-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Host colonization by a pathogen requires proper sensing and response to local environmental cues, to ensure adaptation and continued survival within the host. The ionic milieu represents a critical potential source of environmental cues, and indeed, there has been extensive study of the interplay between host and pathogen in the context of metals such as iron, zinc, and manganese, vital ions that are actively sequestered by the host. The inherent non-uniformity of the ionic milieu also extends, however, to "abundant" ions such as chloride and potassium, whose concentrations vary greatly between tissue and cellular locations, and with the immune response. Despite this, the concept of abundant ions as environmental cues and key players in host-pathogen interactions is only just emerging. Focusing on chloride and potassium, this review brings together studies across multiple bacterial and parasitic species that have begun to define both how these abundant ions are exploited as cues during host infection, and how they can be actively manipulated by pathogens during host colonization. The close links between ion homeostasis and sensing/response to different ionic signals, and the importance of studying pathogen response to cues in combination, are also discussed, while considering the fundamental insight still to be uncovered from further studies in this nascent area of inquiry.
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18
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Berdejo D, Merino N, Pagán E, García-Gonzalo D, Pagán R. Genetic Variants and Phenotypic Characteristics of Salmonella Typhimurium-Resistant Mutants after Exposure to Carvacrol. Microorganisms 2020; 8:microorganisms8060937. [PMID: 32580471 PMCID: PMC7356045 DOI: 10.3390/microorganisms8060937] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 12/12/2022] Open
Abstract
The emergence of antimicrobial resistance has raised questions about the safety of essential oils and their individual constituents as food preservatives and as disinfection agents. Further research is required to understand how and under what conditions stable genotypic resistance might occur in food pathogens. Evolution experiments on Salmonella Typhimurium cyclically exposed to sublethal and lethal doses of carvacrol permitted the isolation of SeSCar and SeLCar strains, respectively. Both evolved strains showed a significant increase in carvacrol resistance, assessed by minimum inhibitory and bactericidal concentrations, the study of growth kinetics in the presence of carvacrol, and the evaluation of survival under lethal conditions. Moreover, antibiotic susceptibility tests revealed a development of SeLCar resistance to a wide range of antibiotics. Whole genome sequencing allowed the identification of single nucleotide variations in transcriptional regulators of oxidative stress-response: yfhP in SeSCar and soxR in SeLCar, which could be responsible for the increased resistance by improving the response to carvacrol and preventing its accumulation inside the cell. This study demonstrates the emergence of S. Typhimurium-resistant mutants against carvacrol, which might pose a risk to food safety and should therefore be considered in the design of food preservation strategies, or of cleaning and disinfection treatments.
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19
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Tascón I, Sousa JS, Corey RA, Mills DJ, Griwatz D, Aumüller N, Mikusevic V, Stansfeld PJ, Vonck J, Hänelt I. Structural basis of proton-coupled potassium transport in the KUP family. Nat Commun 2020; 11:626. [PMID: 32005818 PMCID: PMC6994465 DOI: 10.1038/s41467-020-14441-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/10/2020] [Indexed: 12/05/2022] Open
Abstract
Potassium homeostasis is vital for all organisms, but is challenging in single-celled organisms like bacteria and yeast and immobile organisms like plants that constantly need to adapt to changing external conditions. KUP transporters facilitate potassium uptake by the co-transport of protons. Here, we uncover the molecular basis for transport in this widely distributed family. We identify the potassium importer KimA from Bacillus subtilis as a member of the KUP family, demonstrate that it functions as a K+/H+ symporter and report a 3.7 Å cryo-EM structure of the KimA homodimer in an inward-occluded, trans-inhibited conformation. By introducing point mutations, we identify key residues for potassium and proton binding, which are conserved among other KUP proteins. KUP transporters facilitate potassium uptake by the co-transport of protons and are key players in potassium homeostasis. Here authors identify the potassium importer KimA from Bacillus subtilis as a new member of the KUP transporter family and show the cryo-EM structure of KimA in an inward-occluded, trans-inhibited conformation.
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Affiliation(s)
- Igor Tascón
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Joana S Sousa
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - David Griwatz
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Nadine Aumüller
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Vedrana Mikusevic
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK.,School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.
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20
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MacGilvary NJ, Kevorkian YL, Tan S. Potassium response and homeostasis in Mycobacterium tuberculosis modulates environmental adaptation and is important for host colonization. PLoS Pathog 2019; 15:e1007591. [PMID: 30716121 PMCID: PMC6375644 DOI: 10.1371/journal.ppat.1007591] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 02/14/2019] [Accepted: 01/22/2019] [Indexed: 11/19/2022] Open
Abstract
Successful host colonization by bacteria requires sensing and response to the local ionic milieu, and coordination of responses with the maintenance of ionic homeostasis in the face of changing conditions. We previously discovered that Mycobacterium tuberculosis (Mtb) responds synergistically to chloride (Cl-) and pH, as cues to the immune status of its host. This raised the intriguing concept of abundant ions as important environmental signals, and we have now uncovered potassium (K+) as an ion that can significantly impact colonization by Mtb. The bacterium has a unique transcriptional response to changes in environmental K+ levels, with both distinct and shared regulatory mechanisms controlling Mtb response to the ionic signals of K+, Cl-, and pH. We demonstrate that intraphagosomal K+ levels increase during macrophage phagosome maturation, and find using a novel fluorescent K+-responsive reporter Mtb strain that K+ is not limiting during macrophage infection. Disruption of Mtb K+ homeostasis by deletion of the Trk K+ uptake system results in dampening of the bacterial response to pH and Cl-, and attenuation in host colonization, both in primary murine bone marrow-derived macrophages and in vivo in a murine model of Mtb infection. Our study reveals how bacterial ionic homeostasis can impact environmental ionic responses, and highlights the important role that abundant ions can play during host colonization by Mtb.
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Affiliation(s)
- Nathan J. MacGilvary
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Yuzo L. Kevorkian
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, United States of America
| | - Shumin Tan
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, United States of America
- * E-mail:
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21
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Blaženović I, Oh YT, Li F, Ji J, Nguyen AK, Wancewicz B, Bender JM, Fiehn O, Youn JH. Effects of Gut Bacteria Depletion and High-Na + and Low-K + Intake on Circulating Levels of Biogenic Amines. Mol Nutr Food Res 2018; 63:e1801184. [PMID: 30513547 DOI: 10.1002/mnfr.201801184] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/13/2018] [Indexed: 12/18/2022]
Abstract
SCOPE High-sodium and low-potassium (HNaLK) content in Western diets increases the risk of hypertension and cardiovascular disease (CVD). It is investigated if the dietary minerals interact with gut bacteria to modulate circulating levels of biogenic amines, which are implicated in various pathologies, including hypertension and CVD. METHODS AND RESULTS Using a metabolomic approach to target biogenic amines, the effects of gut bacteria depletion and HNaLK intake on circulating levels of biogenic amines in rats are examined. Forty-five metabolites whose plasma levels are significantly altered by gut bacteria depletion (p < 0.05) are found, indicating their regulation by gut bacteria. Many of them are not previously linked to gut bacteria; therefore, these data provide novel insights into physiological or pathological roles of gut bacteria. A number of plasma metabolites that are altered both by gut bacteria and HNaLK intake are also found, suggesting possible interactions of the diet and gut bacteria in the modulation of these metabolites. The diet effects are observed with significant changes in the gut bacterial taxa Porphyromonadaceae and Prevotellaceae (p < 0.05). CONCLUSION The dietary minerals may regulate abundances of certain gut bacteria to alter circulating levels of biogenic amines, which may be linked to host physiology or pathology.
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Affiliation(s)
- Ivana Blaženović
- West Coast Metabolomics Center, University of California Davis Genome Center, Davis, CA 95616, USA
| | - Young Taek Oh
- Department of Physiology and Neuroscience, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
| | - Fan Li
- Single Cell, Sequencing, and CyTOF Core Lab, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Jian Ji
- West Coast Metabolomics Center, University of California Davis Genome Center, Davis, CA 95616, USA.,School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, School of Food Science Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China
| | - Ahn-Khoi Nguyen
- Department of Exercise Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Benjamin Wancewicz
- West Coast Metabolomics Center, University of California Davis Genome Center, Davis, CA 95616, USA
| | - Jeffrey M Bender
- USC Keck School of Medicine and Children's Hospital Los Angeles, Los Angeles, CA 90027, USA
| | - Oliver Fiehn
- West Coast Metabolomics Center, University of California Davis Genome Center, Davis, CA 95616, USA.,Department of Biochemistry, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Jang H Youn
- Department of Physiology and Neuroscience, Keck School of Medicine of USC, Los Angeles, CA 90089, USA
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22
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Silva AF, Borges A, Freitas CF, Hioka N, Mikcha JMG, Simões M. Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal and Erythrosine Is Effective in the Control of Food-Related Bacteria in Planktonic and Biofilm States. Molecules 2018; 23:molecules23092288. [PMID: 30205468 PMCID: PMC6225188 DOI: 10.3390/molecules23092288] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 08/28/2018] [Accepted: 09/05/2018] [Indexed: 12/19/2022] Open
Abstract
The thermal and chemical-based methods applied for microbial control in the food industry are not always environmentally friendly and may change the nutritional and organoleptic characteristics of the final products. Moreover, the efficacy of sanitizing agents may be reduced when microbial cells are enclosed in biofilms. The objective of this study was to investigate the effect of photodynamic inactivation, using two xanthene dyes (rose bengal and erythrosine) as photosensitizing agents and green LED as a light source, against Staphylococcus aureus, Listeria innocua, Enterococcus hirae and Escherichia coli in both planktonic and biofilm states. Both photosensitizing agents were able to control planktonic cells of all bacteria tested. The treatments altered the physicochemical properties of cells surface and also induced potassium leakage, indicating damage of cell membranes. Although higher concentrations of the photosensitizing agents (ranging from 0.01 to 50.0 μmol/L) were needed to be applied, the culturability of biofilm cells was reduced to undetectable levels. This finding was confirmed by the live/dead staining, where propidium iodide-labeled bacteria numbers reached up to 100%. The overall results demonstrated that photoinactivation by rose bengal and erythrosine may be a powerful candidate for the control of planktonic cells and biofilms in the food sector.
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Affiliation(s)
- Alex Fiori Silva
- Postgraduate Program of Health Sciences, State University of Maringá, Av. Colombo, 5790, Maringá 87020-900, Paraná, Brazil.
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
| | - Anabela Borges
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
| | - Camila Fabiano Freitas
- Department of Chemistry, State University of Maringa, Av. Colombo, 5790, Maringá 87020-900, Paraná, Brazil.
| | - Noboru Hioka
- Department of Chemistry, State University of Maringa, Av. Colombo, 5790, Maringá 87020-900, Paraná, Brazil.
| | - Jane Martha Graton Mikcha
- Postgraduate Program of Health Sciences, State University of Maringá, Av. Colombo, 5790, Maringá 87020-900, Paraná, Brazil.
| | - Manuel Simões
- LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
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Kaur UJ, Preet S, Rishi P. Augmented antibiotic resistance associated with cadmium induced alterations in Salmonella enterica serovar Typhi. Sci Rep 2018; 8:12818. [PMID: 30143701 PMCID: PMC6109086 DOI: 10.1038/s41598-018-31143-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 08/13/2018] [Indexed: 01/09/2023] Open
Abstract
In view of the reports on co-selection of metal and antibiotic resistance, recently we have reported that increased cadmium accumulation in Salmonella Typhi Ty2 leads to increased antibiotic resistance. In continuation, the present study was carried to substantiate this association in clinical isolates. Interestingly, the levels of cadmium were found to be more in the clinical isolates which co-related with their antibiotic sensitivity/resistance pattern. On cadmium accumulation, antibiotic(s) sensitive isolates were rendered resistant and the resistant isolates were rendered more resistant as per their minimum inhibitory concentration(s). Further, after subjecting the pathogen to cadmium accumulation, alterations occurring in the cells were assessed. Transgenerational cadmium exposure led to changes in growth response, morphology, proteome, elevated antioxidants other than SOD, increased biofilm formation, decreased intracellular macrophage killing coupled with upregulation of genes encoding metallothionein and metal transporters. Thus, these results indicate that cadmium, if acquired from the environment, being non-degradable can exert a long-lasting selective pressure on Salmonella in the host which may display antibiotic resistance later on, as a result of co-selection. Therefore, appropriate strategies need to be developed to inhibit such an enduring pressure of heavy metals, as these represent one of the factors for the emerging antibiotic resistance in pathogens.
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Affiliation(s)
- Ujjwal Jit Kaur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Simran Preet
- Department of Biophysics, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Panjab University, Chandigarh, India.
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Stress Responses, Adaptation, and Virulence of Bacterial Pathogens During Host Gastrointestinal Colonization. Microbiol Spectr 2017; 4. [PMID: 27227312 DOI: 10.1128/microbiolspec.vmbf-0007-2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Invading pathogens are exposed to a multitude of harmful conditions imposed by the host gastrointestinal tract and immune system. Bacterial defenses against these physical and chemical stresses are pivotal for successful host colonization and pathogenesis. Enteric pathogens, which are encountered due to the ingestion of or contact with contaminated foods or materials, are highly successful at surviving harsh conditions to colonize and cause the onset of host illness and disease. Pathogens such as Campylobacter, Helicobacter, Salmonella, Listeria, and virulent strains of Escherichia have evolved elaborate defense mechanisms to adapt to the diverse range of stresses present along the gastrointestinal tract. Furthermore, these pathogens contain a multitude of defenses to help survive and escape from immune cells such as neutrophils and macrophages. This chapter focuses on characterized bacterial defenses against pH, osmotic, oxidative, and nitrosative stresses with emphasis on both the direct and indirect mechanisms that contribute to the survival of each respective stress response.
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25
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McDonough AA, Youn JH. Potassium Homeostasis: The Knowns, the Unknowns, and the Health Benefits. Physiology (Bethesda) 2017; 32:100-111. [PMID: 28202621 PMCID: PMC5337831 DOI: 10.1152/physiol.00022.2016] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Potassium homeostasis has a very high priority because of its importance for membrane potential. Although extracellular K+ is only 2% of total body K+, our physiology was evolutionarily tuned for a high-K+, low-Na+ diet. We review how multiple systems interface to accomplish fine K+ balance and the consequences for health and disease.
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Affiliation(s)
- Alicia A McDonough
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Jang H Youn
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
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Zhi XY, Jiang Z, Yang LL, Huang Y. The underlying mechanisms of genetic innovation and speciation in the family Corynebacteriaceae: A phylogenomics approach. Mol Phylogenet Evol 2017; 107:246-255. [DOI: 10.1016/j.ympev.2016.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/04/2016] [Accepted: 11/14/2016] [Indexed: 01/01/2023]
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Thornbrough JM, Gopinath A, Hundley T, Worley MJ. Human Genome-Wide RNAi Screen for Host Factors That Facilitate Salmonella Invasion Reveals a Role for Potassium Secretion in Promoting Internalization. PLoS One 2016; 11:e0166916. [PMID: 27880807 PMCID: PMC5120809 DOI: 10.1371/journal.pone.0166916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
Salmonella enterica can actively invade the gastro-intestinal epithelium. This frequently leads to diarrheal disease, and also gives the pathogen access to phagocytes that can serve as vehicles for dissemination into deeper tissue. The ability to invade host cells is also important in maintaining the carrier state. While much is known about the bacterial factors that promote invasion, relatively little is known about the host factors involved. To gain insight into how Salmonella enterica serovar Typhimurium is able to invade normally non-phagocytic cells, we undertook a global RNAi screen with S. Typhimurium-infected human epithelial cells. In all, we identified 633 genes as contributing to bacterial internalization. These genes fall into a diverse group of functional categories revealing that cytoskeletal regulators are not the only factors that modulate invasion. In fact, potassium ion transport was the most enriched molecular function category in our screen, reinforcing a link between potassium and internalization. In addition to providing new insights into the molecular mechanisms underlying the ability of pathogens to invade host cells, all 633 host factors identified are candidates for new anti-microbial targets for treating Salmonella infections, and may be useful in curtailing infections with other pathogens as well.
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Affiliation(s)
- Joshua M. Thornbrough
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Adarsh Gopinath
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Tom Hundley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Micah J. Worley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, 40202, United States of America
- * E-mail:
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28
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Durand A, Sinha AK, Dard-Dascot C, Michel B. Mutations Affecting Potassium Import Restore the Viability of the Escherichia coli DNA Polymerase III holD Mutant. PLoS Genet 2016; 12:e1006114. [PMID: 27280472 PMCID: PMC4900610 DOI: 10.1371/journal.pgen.1006114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 05/18/2016] [Indexed: 11/18/2022] Open
Abstract
Mutants lacking the ψ (HolD) subunit of the Escherichia coli DNA Polymerase III holoenzyme (Pol III HE) have poor viability, but a residual growth allows the isolation of spontaneous suppressor mutations that restore ΔholD mutant viability. Here we describe the isolation and characterization of two suppressor mutations in the trkA and trkE genes, involved in the main E. coli potassium import system. Viability of ΔholD trk mutants is abolished on media with low or high K+ concentrations, where alternative K+ import systems are activated, and is restored on low K+ concentrations by the inactivation of the alternative Kdp system. These findings show that the ΔholD mutant is rescued by a decrease in K+ import. The effect of trk inactivation is additive with the previously identified ΔholD suppressor mutation lexAind that blocks the SOS response indicating an SOS-independent mechanism of suppression. Accordingly, although lagging-strand synthesis is still perturbed in holD trkA mutants, the trkA mutation allows HolD-less Pol III HE to resist increased levels of the SOS-induced bypass polymerase DinB. trk inactivation is also partially additive with an ssb gene duplication, proposed to stabilize HolD-less Pol III HE by a modification of the single-stranded DNA binding protein (SSB) binding mode. We propose that lowering the intracellular K+ concentration stabilizes HolD-less Pol III HE on DNA by increasing electrostatic interactions between Pol III HE subunits, or between Pol III and DNA, directly or through a modification of the SSB binding mode; these three modes of action are not exclusive and could be additive. To our knowledge, the holD mutant provides the first example of an essential protein-DNA interaction that strongly depends on K+ import in vivo.
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Affiliation(s)
- Adeline Durand
- Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Anurag Kumar Sinha
- Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Cloelia Dard-Dascot
- High-throughput Sequencing facility, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Bénédicte Michel
- Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
- * E-mail:
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29
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Li D, Zeng S, He M, Gu AZ. Water Disinfection Byproducts Induce Antibiotic Resistance-Role of Environmental Pollutants in Resistance Phenomena. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:3193-201. [PMID: 26928861 PMCID: PMC6321747 DOI: 10.1021/acs.est.5b05113] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The spread of antibiotic resistance represents a global threat to public health, and has been traditionally attributed to extensive antibiotic uses in clinical and agricultural applications. As a result, researchers have mostly focused on clinically relevant high-level resistance enriched by antibiotics above the minimal inhibitory concentrations (MICs). Here, we report that two common water disinfection byproducts (chlorite and iodoacetic acid) had antibiotic-like effects that led to the evolution of resistant E. coli strains under both high (near MICs) and low (sub-MIC) exposure concentrations. The subinhibitory concentrations of DBPs selected strains with resistance higher than those evolved under above-MIC exposure concentrations. In addition, whole-genome analysis revealed distinct mutations in small sets of genes known to be involved in multiple drug and drug-specific resistance, as well as in genes not yet identified to play role in antibiotic resistance. The number and identities of genetic mutations were distinct for either the high versus low sub-MIC concentrations exposure scenarios. This study provides evidence and mechanistic insight into the sub-MIC selection of antibiotic resistance by antibiotic-like environmental pollutants such as disinfection byproducts in water, which may be important contributors to the spread of global antibiotic resistance. The results from this study open an intriguing and profound question on the roles of large amount and various environmental contaminants play in selecting and spreading the antibiotics resistance in the environment.
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Affiliation(s)
- Dan Li
- Environmental Simulation and Pollution Control (ESPC) State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, 100084, China
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts 02115, United States
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Siyu Zeng
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Miao He
- Environmental Simulation and Pollution Control (ESPC) State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, 100084, China
| | - April Z. Gu
- Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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30
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Li Y, Liu K, Shen J, Liu Y. Wheat bran intake can attenuate chronic cadmium toxicity in mice gut microbiota. Food Funct 2016; 7:3524-30. [DOI: 10.1039/c6fo00233a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Environmental exposure to pollutants such as heavy metals is responsible for various altered physiological functions that are detrimental to health.
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Affiliation(s)
- Yuhui Li
- Department of Biological and Environmental Engineering
- Hefei University
- China
| | - Kaiyong Liu
- School of Public Health
- Anhui Medical University
- China
| | - Jie Shen
- School of Public Health
- Anhui Medical University
- China
| | - Yehao Liu
- School of Public Health
- Anhui Medical University
- China
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31
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Ryan D, Pati NB, Ojha UK, Padhi C, Ray S, Jaiswal S, Singh GP, Mannala GK, Schultze T, Chakraborty T, Suar M. Global transcriptome and mutagenic analyses of the acid tolerance response of Salmonella enterica serovar Typhimurium. Appl Environ Microbiol 2015; 81:8054-65. [PMID: 26386064 PMCID: PMC4651094 DOI: 10.1128/aem.02172-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/01/2015] [Indexed: 01/18/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is one of the leading causative agents of food-borne bacterial gastroenteritis. Swift invasion through the intestinal tract and successful establishment in systemic organs are associated with the adaptability of S. Typhimurium to different stress environments. Low-pH stress serves as one of the first lines of defense in mammalian hosts, which S. Typhimurium must efficiently overcome to establish an infection. Therefore, a better understanding of the molecular mechanisms underlying the adaptability of S. Typhimurium to acid stress is highly relevant. In this study, we have performed a transcriptome analysis of S. Typhimurium under the acid tolerance response (ATR) and found a large number of genes (∼47%) to be differentially expressed (more than 1.5-fold or less than -1.5-fold; P < 0.01). Functional annotation revealed differentially expressed genes to be associated with regulation, metabolism, transport and binding, pathogenesis, and motility. Additionally, our knockout analysis of a subset of differentially regulated genes facilitated the identification of proteins that contribute to S. Typhimurium ATR and virulence. Mutants lacking genes encoding the K(+) binding and transport protein KdpA, hypothetical protein YciG, the flagellar hook cap protein FlgD, and the nitrate reductase subunit NarZ were significantly deficient in their ATRs and displayed varied in vitro virulence characteristics. This study offers greater insight into the transcriptome changes of S. Typhimurium under the ATR and provides a framework for further research on the subject.
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Affiliation(s)
- Daniel Ryan
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Niladri Bhusan Pati
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Urmesh K Ojha
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | | | - Shilpa Ray
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Sangeeta Jaiswal
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Gajinder P Singh
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
| | - Gopala K Mannala
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tilman Schultze
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Trinad Chakraborty
- Institute of Medical Microbiology, German Centre of Infection Research, Site Giessen-Marburg-Langen, Justus-Liebig-University Giessen, Giessen, Germany
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India
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32
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Liu WH, Liu TC, Mong MC. Antibacterial effects and action modes of asiatic acid. Biomedicine (Taipei) 2015; 5:16. [PMID: 26280399 PMCID: PMC10723755 DOI: 10.7603/s40681-015-0016-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 07/20/2015] [Indexed: 12/17/2023] Open
Abstract
In this study, the antibacterial effects and action modes of asiatic acid against the foodborne bacterial pathogens Escherichia coli O157:H7, Salmonella Typhimurium DT104, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus were examined. Minimal inhibitory concentrations (MICs) of asiatic acid against these bacteria were in the range of 20-40 μg/mL. Minimum bactericidal concentrations of asiatic acid were in the range of 32-52 μg/mL. Asiatic acid at 2X MIC effectively reduced bacterial numbers from 6 log10 to < 2 log10 in all test bacteria within 6 h (P < 0.05). The antibacterial activity of asiatic acid was not affected by heat treatments from 25 to 100°C. Asiatic acid at 1 or 2X MICs caused 40-56% and 71-89% membrane damage in test bacteria within 2 h, respectively In addition, asiatic acid at 1 or 2X MICs led to 1.5-2.4 ppm and 2.9-4.1 ppm K(+) release within 2 hr, respectively. Asiatic acid treatments dose-dependently increased bacterial nucleotide leakage (P < 0.05). After 3 days of storage at 25°C, the addition of asiatic acid dose-dependently inhibited the growth of test bacteria in ground beef (P < 0.05), in which 8 mg asiatic acid treatments led to bacterial levels (log CFU/g) in said ground beef lower than 2. These findings suggest that asiatic acid might be a potent antibacterial agent to prevent food contamination.
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Affiliation(s)
- Wen-Hu Liu
- School of Nutrition, Chung Shan Medical University, 402, Taichung, Taiwan,
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33
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Yost S, Duran-Pinedo AE, Teles R, Krishnan K, Frias-Lopez J. Functional signatures of oral dysbiosis during periodontitis progression revealed by microbial metatranscriptome analysis. Genome Med 2015; 7:27. [PMID: 25918553 PMCID: PMC4410737 DOI: 10.1186/s13073-015-0153-3] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/09/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Periodontitis is a polymicrobial biofilm-induced inflammatory disease that affects 743 million people worldwide. The current model to explain periodontitis progression proposes that changes in the relative abundance of members of the oral microbiome lead to dysbiosis in the host-microbiome crosstalk and then to inflammation and bone loss. Using combined metagenome/metatranscriptome analysis of the subgingival microbiome in progressing and non-progressing sites, we have characterized the distinct molecular signatures of periodontitis progression. METHODS Metatranscriptome analysis was conducted on samples from subgingival biofilms from progressing and stable sites from periodontitis patients. Community-wide expression profiles were obtained using Next Generation Sequencing (Illumina). Sequences were aligned using 'bowtie2' against a constructed oral microbiome database. Differential expression analysis was performed using the non-parametric algorithm implemented on the R package 'NOISeqBio'. We summarized global functional activities of the oral microbial community by set enrichment analysis based on the Gene Ontology (GO) orthology. RESULTS Gene ontology enrichment analysis showed an over-representation in the baseline of active sites of terms related to cell motility, lipid A and peptidoglycan biosynthesis, and transport of iron, potassium, and amino acids. Periodontal pathogens (Tannerella forsythia and Porphyromonas gingivalis) upregulated different TonB-dependent receptors, peptidases, proteases, aerotolerance genes, iron transport genes, hemolysins, and CRISPR-associated genes. Surprisingly, organisms that have not been usually associated with the disease (Streptococcus oralis, Streptococcus mutans, Streptococcus intermedius, Streptococcus mitis, Veillonella parvula, and Pseudomonas fluorenscens) were highly active transcribing putative virulence factors. We detected patterns of activities associated with progression of clinical traits. Among those we found that the profiles of expression of cobalamin biosynthesis, proteolysis, and potassium transport were associated with the evolution towards disease. CONCLUSIONS We identified metabolic changes in the microbial community associated with the initial stages of dysbiosis. Regardless of the overall composition of the community, certain metabolic signatures are consistent with disease progression. Our results suggest that the whole community, and not just a handful of oral pathogens, is responsible for an increase in virulence that leads to progression. TRIAL REGISTRATION NCT01489839, 6 December 2011.
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Affiliation(s)
- Susan Yost
- />Forsyth Institute, 245 First Street, Cambridge, Massachusetts 02142 USA
| | - Ana E Duran-Pinedo
- />Forsyth Institute, 245 First Street, Cambridge, Massachusetts 02142 USA
| | - Ricardo Teles
- />University of North Carolina Chapel Hill, School of Dentistry, Chapel Hill, NC 27599-7450 USA
| | - Keerthana Krishnan
- />Forsyth Institute, 245 First Street, Cambridge, Massachusetts 02142 USA
| | - Jorge Frias-Lopez
- />Forsyth Institute, 245 First Street, Cambridge, Massachusetts 02142 USA
- />Harvard School of Dental Medicine, 188 Longwood Ave, Boston, MA 02115 USA
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34
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Gannoun-Zaki L, Belon C, Dupont C, Hilbert F, Kremer L, Blanc-Potard AB. Overexpression of theSalmonellaKdpF membrane peptide modulates expression ofkdpgenes and intramacrophage growth. FEMS Microbiol Lett 2014; 359:34-41. [DOI: 10.1111/1574-6968.12559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 07/09/2014] [Accepted: 07/25/2014] [Indexed: 11/30/2022] Open
Affiliation(s)
- Laila Gannoun-Zaki
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Claudine Belon
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Christian Dupont
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
| | - Friederike Hilbert
- Institute of Meat Hygiene; Meat Technology and Food Science; University of Veterinary Medicine Vienna; Vienna Austria
| | - Laurent Kremer
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
- INSERM; DIMNP; CNRS-UMR5235; Montpellier France
| | - Anne-Béatrice Blanc-Potard
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques; Universités de Montpellier 2 et 1; CNRS-UMR5235; Montpellier; France
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