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Maciel-Guerra A, Babaarslan K, Baker M, Rahman A, Hossain M, Sadique A, Alam J, Uzzaman S, Ferdous Rahman Sarker M, Sultana N, Islam Khan A, Ara Begum Y, Hassan Afrad M, Senin N, Hossain Habib Z, Shirin T, Qadri F, Dottorini T. Core and accessory genomic traits of Vibrio cholerae O1 drive lineage transmission and disease severity. Nat Commun 2024; 15:8231. [PMID: 39313510 PMCID: PMC11420230 DOI: 10.1038/s41467-024-52238-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 08/30/2024] [Indexed: 09/25/2024] Open
Abstract
In Bangladesh, Vibrio cholerae lineages are undergoing genomic evolution, with increased virulence and spreading ability. However, our understanding of the genomic determinants influencing lineage transmission and disease severity remains incomplete. Here, we developed a computational framework using machine-learning, genome scale metabolic modelling (GSSM) and 3D structural analysis, to identify V. cholerae genomic traits linked to lineage transmission and disease severity. We analysed in-patients isolates from six Bangladeshi regions (2015-2021), and uncovered accessory genes and core SNPs unique to the most recent dominant lineage, with virulence, motility and bacteriophage resistance functions. We also found a strong correlation between V. cholerae genomic traits and disease severity, with some traits overlapping those driving lineage transmission. GSMM and 3D structure analysis unveiled a complex interplay between transcription regulation, protein interaction and stability, and metabolic networks, associated to lifestyle adaptation, intestinal colonization, acid tolerance and symptom severity. Our findings support advancing therapeutics and targeted interventions to mitigate cholera spread.
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Affiliation(s)
- Alexandre Maciel-Guerra
- School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK
| | - Kubra Babaarslan
- School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK
| | - Michelle Baker
- School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK
| | - Aura Rahman
- NSU Genome Research Institute (NGRI), North South University, Baridhara, Bashundhara, Dhaka, 1229, Bangladesh
| | - Maqsud Hossain
- School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK
- NSU Genome Research Institute (NGRI), North South University, Baridhara, Bashundhara, Dhaka, 1229, Bangladesh
| | - Abdus Sadique
- NSU Genome Research Institute (NGRI), North South University, Baridhara, Bashundhara, Dhaka, 1229, Bangladesh
| | - Jahidul Alam
- NSU Genome Research Institute (NGRI), North South University, Baridhara, Bashundhara, Dhaka, 1229, Bangladesh
| | - Salim Uzzaman
- Institute of Epidemiology, Disease Control and Research (IEDCR), 44, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Mohammad Ferdous Rahman Sarker
- Institute of Epidemiology, Disease Control and Research (IEDCR), 44, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Nasrin Sultana
- Institute of Epidemiology, Disease Control and Research (IEDCR), 44, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Ashraful Islam Khan
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), 68, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Yasmin Ara Begum
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), 68, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Mokibul Hassan Afrad
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), 68, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Nicola Senin
- Department of Engineering, University of Perugia, 06125, Perugia, Italy
| | - Zakir Hossain Habib
- Institute of Epidemiology, Disease Control and Research (IEDCR), 44, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Tahmina Shirin
- Institute of Epidemiology, Disease Control and Research (IEDCR), 44, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr, b), 68, Shaheed Tajuddin Ahmed Sarani Mohakhali, Dhaka, 1212, Bangladesh
| | - Tania Dottorini
- School of Veterinary Medicine and Science, University of Nottingham, College Road, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK.
- Centre for Smart Food Research, Nottingham Ningbo China Beacons of Excellence Research and Innovation Institute, University of Nottingham Ningbo China, Ningbo, 315100, P. R. China.
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Montero DA, Vidal RM, Velasco J, George S, Lucero Y, Gómez LA, Carreño LJ, García-Betancourt R, O’Ryan M. Vibrio cholerae, classification, pathogenesis, immune response, and trends in vaccine development. Front Med (Lausanne) 2023; 10:1155751. [PMID: 37215733 PMCID: PMC10196187 DOI: 10.3389/fmed.2023.1155751] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/14/2023] [Indexed: 05/24/2023] Open
Abstract
Vibrio cholerae is the causative agent of cholera, a highly contagious diarrheal disease affecting millions worldwide each year. Cholera is a major public health problem, primarily in countries with poor sanitary conditions and regions affected by natural disasters, where access to safe drinking water is limited. In this narrative review, we aim to summarize the current understanding of the evolution of virulence and pathogenesis of V. cholerae as well as provide an overview of the immune response against this pathogen. We highlight that V. cholerae has a remarkable ability to adapt and evolve, which is a global concern because it increases the risk of cholera outbreaks and the spread of the disease to new regions, making its control even more challenging. Furthermore, we show that this pathogen expresses several virulence factors enabling it to efficiently colonize the human intestine and cause cholera. A cumulative body of work also shows that V. cholerae infection triggers an inflammatory response that influences the development of immune memory against cholera. Lastly, we reviewed the status of licensed cholera vaccines, those undergoing clinical evaluation, and recent progress in developing next-generation vaccines. This review offers a comprehensive view of V. cholerae and identifies knowledge gaps that must be addressed to develop more effective cholera vaccines.
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Affiliation(s)
- David A. Montero
- Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Roberto M. Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Juliana Velasco
- Unidad de Paciente Crítico, Clínica Hospital del Profesor, Santiago, Chile
- Programa de Formación de Especialista en Medicina de Urgencia, Universidad Andrés Bello, Santiago, Chile
| | - Sergio George
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Yalda Lucero
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Pediatría y Cirugía Infantil, Hospital Dr. Roberto del Rio, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Leonardo A. Gómez
- Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Leandro J. Carreño
- Instituto Milenio de Inmunología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Programa de Inmunología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Richard García-Betancourt
- Programa de Inmunología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Miguel O’Ryan
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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Grant TA, López-Pérez M, Haro-Moreno JM, Almagro-Moreno S. Allelic diversity uncovers protein domains contributing to the emergence of antimicrobial resistance. PLoS Genet 2023; 19:e1010490. [PMID: 36972246 PMCID: PMC10079234 DOI: 10.1371/journal.pgen.1010490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 04/06/2023] [Accepted: 03/06/2023] [Indexed: 03/29/2023] Open
Abstract
Antimicrobial resistance (AMR) remains a major threat to global health. To date, tractable approaches that decipher how AMR emerges within a bacterial population remain limited. Here, we developed a framework that exploits genetic diversity from environmental bacterial populations to decode emergent phenotypes such as AMR. OmpU is a porin that can make up to 60% of the outer membrane of Vibrio cholerae, the cholera pathogen. This porin is directly associated with the emergence of toxigenic clades and confers resistance to numerous host antimicrobials. In this study, we examined naturally occurring allelic variants of OmpU in environmental V. cholerae and established associations that connected genotypic variation with phenotypic outcome. We covered the landscape of gene variability and found that the porin forms two major phylogenetic clusters with striking genetic diversity. We generated 14 isogenic mutant strains, each encoding a unique ompU allele, and found that divergent genotypes lead to convergent antimicrobial resistance profiles. We identified and characterized functional domains in OmpU unique to variants conferring AMR-associated phenotypes. Specifically, we identified four conserved domains that are linked with resistance to bile and host-derived antimicrobial peptides. Mutant strains for these domains exhibit differential susceptibility patterns to these and other antimicrobials. Interestingly, a mutant strain in which we exchanged the four domains of the clinical allele for those of a sensitive strain exhibits a resistance profile closer to a porin deletion mutant. Finally, using phenotypic microarrays, we uncovered novel functions of OmpU and their connection with allelic variability. Our findings highlight the suitability of our approach towards dissecting the specific protein domains associated with the emergence of AMR and can be naturally extended to other bacterial pathogens and biological processes.
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Affiliation(s)
- Trudy-Ann Grant
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
| | - Mario López-Pérez
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
| | - Jose Manuel Haro-Moreno
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, San Juan, Alicante, Spain
| | - Salvador Almagro-Moreno
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, United States of America
- * E-mail:
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Kostiuk B, Becker ME, Churaman CN, Black JJ, Payne SM, Pukatzki S, Koestler BJ. Vibrio cholerae Alkalizes Its Environment via Citrate Metabolism to Inhibit Enteric Growth In Vitro. Microbiol Spectr 2023; 11:e0491722. [PMID: 36916917 PMCID: PMC10100763 DOI: 10.1128/spectrum.04917-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/22/2023] [Indexed: 03/16/2023] Open
Abstract
Vibrio cholerae is a Gram-negative pathogen, living in constant competition with other bacteria in marine environments and during human infection. One competitive advantage of V. cholerae is the ability to metabolize diverse carbon sources, such as chitin and citrate. We observed that when some V. cholerae strains were grown on a medium with citrate, the medium's chemical composition turned into a hostile alkaline environment for Gram-negative bacteria, such as Escherichia coli and Shigella flexneri. We found that although the ability to exclude competing bacteria was not contingent on exogenous citrate, V. cholerae C6706 citrate metabolism mutants ΔoadA-1, ΔcitE, and ΔcitF were not able to inhibit S. flexneri or E. coli growth. Lastly, we demonstrated that while the V. cholerae C6706-mediated increased medium pH was necessary for the enteric exclusion phenotype, secondary metabolites, such as bicarbonate (protonated to carbonate in the raised pH) from the metabolism of citrate, enhanced the ability to inhibit the growth of E. coli. These data provide a novel example of how V. cholerae outcompetes other Gram-negative bacteria. IMPORTANCE Vibrio cholerae must compete with other bacteria in order to cause disease. Here, we show that V. cholerae creates an alkaline environment, which is able to inhibit the growth of other enteric bacteria. We demonstrate that V. cholerae environmental alkalization is linked to the capacity of the bacteria to metabolize citrate. This behavior could potentially contribute to V. cholerae's ability to colonize the human intestine.
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Affiliation(s)
- Benjamin Kostiuk
- Department of Medical Microbiology and Immunology, 6-020 Katz Group Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Mark E. Becker
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Candice N. Churaman
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan, USA
| | - Joshua J. Black
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shelley M. Payne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Stefan Pukatzki
- Department of Biology, The City College of New York, New York, New York, USA
| | - Benjamin J. Koestler
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan, USA
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5
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Cutugno L, Tamayo BKS, Lens PN, O'Byrne C, Pané-Farré J, Boyd A. In vivo characterisation of the Vibrio vulnificus stressosome: A complex involved in reshaping glucose metabolism and motility regulation, in nutrient- and iron-limited growth conditions. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 4:100186. [PMID: 36936406 PMCID: PMC10014275 DOI: 10.1016/j.crmicr.2023.100186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
Stressosomes are signal-sensing and integration hubs identified in many bacteria. At present, the role of the stressosome has only been investigated in Gram-positive bacteria. This work represents the first in vivo characterisation of the stressosome in a Gram-negative bacterium, Vibrio vulnificus. Previous in vitro characterisation of the complex has led to the hypothesis of a complex involved in iron metabolism and control of c-di-GMP levels. We demonstrate that the stressosome is probably involved in reshaping the glucose metabolism in Fe- and nutrient-limited conditions and mutations of the locus affect the activation of the glyoxylate shunt. Moreover, we show that the stressosome is needed for the transcription of fleQ and to promote motility, consistent with the hypothesis that the stressosome is involved in regulating c-di-GMP. This report highlights the potential role of the stressosome in a Gram-negative bacterium, with implications for the metabolism and motility of this pathogen.
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Affiliation(s)
- Laura Cutugno
- School of Natural Sciences, University of Galway, Ireland
| | | | - Piet N.L. Lens
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Conor O'Byrne
- School of Biological and Chemical Sciences, University of Galway, Ireland
| | - Jan Pané-Farré
- Centre for synthetic Microbiology (SYNMIKRO) & Department of Chemistry, Philipps-University Marburg, Germany
| | - Aoife Boyd
- School of Natural Sciences, University of Galway, Ireland
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Yang HW, Lee JH, Zhao Y. RpoN Regulon in Erwinia amylovora Revealed by Transcriptional Profiling and In Silico Binding Site Analysis. PHYTOPATHOLOGY 2023; 113:183-193. [PMID: 35994732 DOI: 10.1094/phyto-07-22-0255-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Erwinia amylovora causes a devastating fire blight disease in apples and pears. One of the main virulence determinants in E. amylovora is the hypersensitive response (HR) and pathogenicity (hrp)-type III secretion system (T3SS), which is activated by the RpoN-HrpL sigma factor cascade. However, the RpoN regulon in E. amylovora has not been investigated. In this study, we determined the RpoN regulon in E. amylovora by combining RNA-seq transcriptomic analysis with in silico binding site analysis. RNA-seq revealed that 262 genes, approximately 7.5% genes in the genome of E. amylovora, were differentially transcribed in the rpoN mutant as compared with the wild type. Specifically, genes associated with virulence, motility, nitrogen assimilation, the PspF system, stress response, and arginine biosynthesis are positively regulated by RpoN, whereas genes associated with biosynthesis of amino acids and sorbitol transport are negatively regulated by RpoN. In silico binding site analysis identified 46 potential target genes with a putative RpoN binding site, and the upstream sequences of six, three, and three genes also contain putative GlnG, PspF, and YfhA binding sites, respectively. Overall, RpoN directly regulates genes associated with virulence, nitrogen assimilation, the PspF system, motility and the YfhA/YfhK two-component regulatory system.
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Affiliation(s)
- Ho-Wen Yang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Jae-Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
- Department of Plant Pathology, WSU-IAREC, Prosser, WA 99350, U.S.A
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Marques PH, Prado LCDS, Felice AG, Rodrigues TCV, Pereira UDP, Jaiswal AK, Azevedo V, Oliveira CJF, Soares S. Insights into the Vibrio Genus: A One Health Perspective from Host Adaptability and Antibiotic Resistance to In Silico Identification of Drug Targets. Antibiotics (Basel) 2022; 11:1399. [PMID: 36290057 PMCID: PMC9598498 DOI: 10.3390/antibiotics11101399] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 10/08/2022] [Accepted: 10/08/2022] [Indexed: 11/23/2022] Open
Abstract
The genus Vibrio comprises an important group of ubiquitous bacteria of marine systems with a high infectious capacity for humans and fish, which can lead to death or cause economic losses in aquaculture. However, little is known about the evolutionary process that led to the adaptation and colonization of humans and also about the consequences of the uncontrollable use of antibiotics in aquaculture. Here, comparative genomics analysis and functional gene annotation showed that the species more related to humans presented a significantly higher amount of proteins associated with colonization processes, such as transcriptional factors, signal transduction mechanisms, and iron uptake. In comparison, those aquaculture-associated species possess a much higher amount of resistance-associated genes, as with those of the tetracycline class. Finally, through subtractive genomics, we propose seven new drug targets such as: UMP Kinase, required to catalyze the phosphorylation of UMP into UDP, essential for the survival of bacteria of this genus; and, new natural molecules, which have demonstrated high affinity for the active sites of these targets. These data also suggest that the species most adaptable to fish and humans have a distinct natural evolution and probably undergo changes due to anthropogenic action in aquaculture or indiscriminate/irregular use of antibiotics.
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Affiliation(s)
- Pedro Henrique Marques
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro, Uberaba 38025-180, MG, Brazil
| | - Lígia Carolina da Silva Prado
- Interunit Bioinformatics Post-Graduate Program, Federal University of Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Andrei Giacchetto Felice
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro, Uberaba 38025-180, MG, Brazil
| | | | - Ulisses de Padua Pereira
- Department of Preventive Veterinary Medicine, Londrina State University, Londrina 86057-970, PR, Brazil
| | - Arun Kumar Jaiswal
- Interunit Bioinformatics Post-Graduate Program, Federal University of Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Vasco Azevedo
- Department of Genetics, Ecology and Evolution, Federal University of Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Carlo José Freire Oliveira
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro, Uberaba 38025-180, MG, Brazil
| | - Siomar Soares
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro, Uberaba 38025-180, MG, Brazil
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Structure, regulation, and host interaction of outer membrane protein U (OmpU) of Vibrio species. Microb Pathog 2021; 162:105267. [PMID: 34718127 DOI: 10.1016/j.micpath.2021.105267] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/30/2021] [Accepted: 10/20/2021] [Indexed: 01/22/2023]
Abstract
OmpU is a multimeric, cation selective outer membrane protein of Vibrio and related species that non-covalently interact with peptidoglycan layer. Interaction of OmpU with human host cells triggers signaling pathways to promote cytokine secretion, reactive oxygen species production, and caspase independent death in immune and epithelial cells. Non-choleric OmpU imparts resistance to antimicrobial peptides and induces actin cytoskeletal reorganization in the host cells. Further, OmpU isolated from Vibrio species elicits an immune response in several aquaculture hosts. Importantly, in-vivo studies using recombinant OmpU or OmpU derived mimotopes reveal a short-lasting immunity, and protection against Vibrio in the aquaculture sector. In conclusion, OmpU is a key adhesion protein and an important virulence factor for successful colonization of Vibrio species into hosts. This review article provides a broad overview of structural, regulatory, and functional mechanisms of OmpU in normal and disease states.
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Gu D, Wang K, Lu T, Li L, Jiao X. Vibrio parahaemolyticus CadC regulates acid tolerance response to enhance bacterial motility and cytotoxicity. JOURNAL OF FISH DISEASES 2021; 44:1155-1168. [PMID: 33831221 PMCID: PMC8359830 DOI: 10.1111/jfd.13376] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/26/2021] [Indexed: 05/15/2023]
Abstract
Pathogens adapted to sub-lethal acidic conditions could increase the virulence and survival ability under lethal conditions. In the aquaculture industry, feed acidifiers have been used to increase the growth of aquatic animals. However, there is limited study on the effects of acidic condition on the virulence and survival of pathogens in aquaculture. In this study, we investigated the survival ability of Vibrio parahaemolyticus at lethal acidic pH (4.0) after adapted the bacteria to sub-lethal acidic pH (5.5) for 1 hr. Our results indicated that the adapted strain increased the survival ability at lethal acidic pH invoked by an inorganic (HCl) or organic (citric) acid. RNA-sequencing (RNA-seq) results revealed that 321 genes were differentially expressed at the sub-lethal acidic pH including cadC, cadBA and groES/groEL relating to acid tolerance response (ATR), as well as genes relating to outer membrane, heat-shock proteins, phosphotransferase system and flagella system. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed that cadC and cadBA were upregulated under sub-lethal acidic conditions. The CadC protein could directly regulate the expression of cadBA to modulate the ATR in V. parahaemolyticus. RNA-seq data also indicated that 113 genes in the CadC-dependent way and 208 genes in the CadC-independent way were differentially expressed, which were related to the regulation of ATR. Finally, the motility and cytotoxicity of the sub-lethal acidic adapted wild type (WT) were significantly increased compared with the unadapted strain. Our results demonstrated that the dietary acidifiers may increase the virulence and survival of V. parahaemolyticus in aquaculture.
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Affiliation(s)
- Dan Gu
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co‐innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou UniversityJiangsuChina
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and QualityMinistry of Agriculture of ChinaYangzhou UniversityYangzhouChina
- Joint International Research Laboratory of Agriculture and Agri‐product Safety of the Ministry of EducationYangzhou UniversityJiangsuChina
| | - Kangru Wang
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co‐innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou UniversityJiangsuChina
| | - Tianyu Lu
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co‐innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou UniversityJiangsuChina
| | - Lingzhi Li
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co‐innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou UniversityJiangsuChina
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co‐innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou UniversityJiangsuChina
- Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and QualityMinistry of Agriculture of ChinaYangzhou UniversityYangzhouChina
- Joint International Research Laboratory of Agriculture and Agri‐product Safety of the Ministry of EducationYangzhou UniversityJiangsuChina
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A Tail Fiber Protein and a Receptor-Binding Protein Mediate ICP2 Bacteriophage Interactions with Vibrio cholerae OmpU. J Bacteriol 2021; 203:e0014121. [PMID: 33875544 DOI: 10.1128/jb.00141-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
ICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor. In this study, we identify the ICP2 proteins that mediate interactions with OmpU by selecting for ICP2 host range mutants within infant rabbits infected with a mixture of wild-type and OmpU mutant strains. ICP2 host range mutants that can now infect OmpU mutant strains have missense mutations in the putative tail fiber gene gp25 and the putative adhesin gene gp23. Using site-specific mutagenesis, we show that single or double mutations in gp25 are sufficient to generate the host range mutant phenotype. However, at least one additional mutation in gp23 is required for robust plaque formation on specific OmpU mutants. Mutations in gp23 alone were insufficient to produce a host range mutant phenotype. All ICP2 host range mutants retained the ability to form plaques on wild-type V. cholerae cells. The strength of binding of host range mutants to V. cholerae correlated with plaque morphology, indicating that the selected mutations in gp25 and gp23 restore molecular interactions with the receptor. We propose that ICP2 host range mutants evolve by a two-step process. First, gp25 mutations are selected for their broad host range, albeit accompanied by low-level phage adsorption. Subsequent selection occurs for gp23 mutations that further increase productive binding to specific OmpU alleles, allowing for near-wild-type efficiencies of adsorption and subsequent phage multiplication. IMPORTANCE Concern over multidrug-resistant bacterial pathogens, including Vibrio cholerae, has led to renewed interest in phage biology and the potential for phage therapy. ICP2 is a genetically unique virulent phage isolated from cholera patient stool samples. It is also one of three phages in a prophylactic cocktail that have been shown to be effective in animal models of infection and the only one of the three that requires a protein receptor (OmpU). This study identifies an ICP2 tail fiber and a receptor binding protein and examines how ICP2 responds to the selective pressures of phage-resistant OmpU mutants. We found that this particular coevolutionary arms race presents fitness costs to both ICP2 and V. cholerae.
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Zhou Y, Lee ZL, Zhu J. On or Off: Life-Changing Decisions Made by Vibrio cholerae Under Stress. INFECTIOUS MICROBES & DISEASES 2020; 2:127-135. [PMID: 38630076 PMCID: PMC7769058 DOI: 10.1097/im9.0000000000000037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 11/25/2022]
Abstract
Vibrio cholerae, the causative agent of the infectious disease, cholera, is commonly found in brackish waters and infects human hosts via the fecal-oral route. V. cholerae is a master of stress resistance as V. cholerae's dynamic lifestyle across different physical environments constantly exposes it to diverse stressful circumstances. Specifically, V. cholerae has dedicated genetic regulatory networks to sense different environmental cues and respond to these signals. With frequent outbreaks costing a tremendous amount of lives and increased global water temperatures providing more suitable aquatic habitats for V. cholerae, cholera pandemics remain a probable catastrophic threat to humanity. Understanding how V. cholerae copes with different environmental stresses broadens our repertoire of measures against infectious diseases and expands our general knowledge of prokaryotic stress responses. In this review, we summarize the regulatory mechanisms of how V. cholerae fights against stresses in vivo and in vitro.
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Espinoza-Vergara G, Hoque MM, McDougald D, Noorian P. The Impact of Protozoan Predation on the Pathogenicity of Vibrio cholerae. Front Microbiol 2020; 11:17. [PMID: 32038597 PMCID: PMC6985070 DOI: 10.3389/fmicb.2020.00017] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/07/2020] [Indexed: 12/16/2022] Open
Abstract
In the aquatic environment, Vibrio spp. interact with many living organisms that can serve as a replication niche, including heterotrophic protists, or protozoa. Protozoa engulf bacteria and package them into phagosomes where the cells are exposed to low pH, antimicrobial peptides, reactive oxygen/nitrogen species, proteolytic enzymes, and low concentrations of essential metal ions such as iron. However, some bacteria can resist these digestive processes. For example, Vibrio cholerae and Vibrio harveyi can resist intracellular digestion. In order to survive intracellularly, bacteria have acquired and/or developed specific factors that help them to resist the unfavorable conditions encountered inside of the phagosomes. Many of these intra-phagosomal factors used to kill and digest bacteria are highly conserved between eukaryotic cells and thus are also expressed by the innate immune system in the gastrointestinal tract as the first line of defense against bacterial pathogens. Since pathogenic bacteria have been shown to be hypervirulent after they have passed through protozoa, the resistance to digestion by protist hosts in their natural environment plays a key role in enhancing the infectious potential of pathogenic Vibrio spp. This review will investigate the current knowledge in interactions of bacteria with protozoa and human host to better understand the mechanisms used by both protozoa and human hosts to kill bacteria and the bacterial response to them.
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Affiliation(s)
- Gustavo Espinoza-Vergara
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - M Mozammel Hoque
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
| | - Diane McDougald
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia.,Faculty of Science, Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Parisa Noorian
- Faculty of Science, The ithree Institute, University of Technology Sydney, Sydney, NSW, Australia
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13
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Lv T, Dai F, Zhuang Q, Zhao X, Shao Y, Guo M, Lv Z, Li C, Zhang W. Outer membrane protein OmpU is related to iron balance in Vibrio alginolyticus. Microbiol Res 2019; 230:126350. [PMID: 31629270 DOI: 10.1016/j.micres.2019.126350] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/01/2019] [Accepted: 10/06/2019] [Indexed: 12/14/2022]
Abstract
Outer membrane protein U (OmpU) is a major porin from Vibrio alginolyticus and has been considered a vaccine candidate against infection by V. alginolyticus. After pre-incubated with polyclonal antibody against rOmpU, V. alginolyticus showed a 78% decrease in extracellular iron level, suggesting that interruption of OmpU could increase intracellular iron level. The mRNA expression of ompU under iron-limited conditions was determined using real-time reverse transcriptase PCR. The mRNA level of ompU was downregulated to 0.27-, 0.036- and 0.019-fold after the addition of the iron chelator 2,2'-bipyridyl for 10, 30 and 60 min, respectively. In addition, the promoter of ompU contained a ferric uptake regulator (Fur) binding site, which revealed the potential regulation of ompU by Fur and iron. Fur from V. alginolyticus was purified and used for electrophoretic mobility shift assay. The result showed that in the absence of Fe2+, purified recombinant Fur could specifically bind to the promoter DNA of ompU, while in the presence of Fe2+, the binding of Fur and the promoter DNA was suppressed. Our study preliminarily explored the function of OmpU in iron balance in V. alginolyticus, and these findings were helpful in understanding iron metabolism in V. alginolyticus.
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Affiliation(s)
- Tengteng Lv
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Fa Dai
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Qiuting Zhuang
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Xuelin Zhao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Yina Shao
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Ming Guo
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Zhimeng Lv
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China
| | - Chenghua Li
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China
| | - Weiwei Zhang
- State Key Laboratory for Quality and Safety of Agro-products, Ningbo University, Ningbo, 315211, PR China.
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14
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Vibrio cholerae residing in food vacuoles expelled by protozoa are more infectious in vivo. Nat Microbiol 2019; 4:2466-2474. [PMID: 31570868 DOI: 10.1038/s41564-019-0563-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 07/19/2019] [Indexed: 11/09/2022]
Abstract
Vibrio cholerae interacts with many organisms in the environment, including heterotrophic protists (protozoa). Several species of protozoa have been reported to release undigested bacteria in expelled food vacuoles (EFVs) when feeding on some pathogens. While the production of EFVs has been reported, their biological role as a vector for the transmission of pathogens remains unknown. Here we report that ciliated protozoa release EFVs containing V. cholerae. The EFVs are stable, the cells inside them are protected from multiple stresses, and large numbers of cells escape when incubated at 37 °C or in the presence of nutrients. We show that OmpU, a major outer membrane protein positively regulated by ToxR, has a role in the production of EFVs. Notably, cells released from EFVs have growth and colonization advantages over planktonic cells both in vitro and in vivo. Our results suggest that EFVs facilitate V. cholerae survival in the environment, enhancing their infectious potential and may contribute to the dissemination of epidemic V. cholerae strains. These results improve our understanding of the mechanisms of persistence and the modes of transmission of V. cholerae and may further apply to other opportunistic pathogens that have been shown to be released by protists in EFVs.
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15
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Fadel HM, El-Lamie MM. Vibriosis and Aeromonas infection in shrimp: Isolation, sequencing, and control. INTERNATIONAL JOURNAL OF ONE HEALTH 2019. [DOI: 10.14202/ijoh.2019.38-48] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background and Aim: Shrimp is one of the most commonly consumed types of seafood. It is a very nutritious healthy food. Shrimp is low in calories and rich in protein and healthy fats. It also contains a treasure trove of vitamins and minerals. On the negative side, it may be affected by many bacterial diseases which affect its health. Furthermore, it may be incriminated as a vector of foodborne illnesses that range from mild gastrointestinal upset to life-threatening diseases. This study was designed to assess the clinical picture and zoonotic importance of vibriosis and Aeromonas infection in live shrimp and to study the antibacterial effect of citric acid (lemon juice) and acetic acid (vinegar) on these pathogens. Materials and Methods: A total of 170 live shrimp (Metapenaeus monoceros) samples were collected from Suez City, Egypt. The samples were examined clinically, and then, they were enriched into alkaline peptone water and cultivated on thiosulfate-citrate-bile salts-sucrose agar and ampicillin MacConkey agar for the isolation of Vibrio and Aeromonas species, respectively. The recovered isolates were confirmed biochemically and genotypically using duplex polymerase chain reaction (PCR) and sequencing. The germicidal effects of vinegar and lemon on artificially contaminated shrimp samples with Aeromonas hydrophila and Vibrio parahaemolyticus at different times (0.25, 1, 1.5, and 24 h) and temperatures (5° and 30°C) were studied. Results: The results revealed that some of the infected shrimp were hypoxic, lethargic with abnormal swimming behavior. In most cases, body appendages, telsons, uropods, and gills took black coloration. In addition, the hepatopancreas appeared soft, swollen, and congested. The prevalence rates of vibriosis in each of the musculature and hepatopancreas were 4.7%, while the prevalence rates of Aeromonas infection in the musculature and hepatopancreas were 11.8% and 11.2%, respectively. Duplex PCR showed that Aeromonas isolates gave double bands: 237 bp specific for gcat and 500 bp specific for 16S rRNA, while Vibrio spp. and Plesiomonas shigelloides isolates gave single band at 500 bp. The effect of organic acid treatment showed that acetic acid (vinegar 5%) had increasing reduction rates that reached its maximum level after 24 h; where it caused (100% inhibition) for A. hydrophila at both temperatures and (33.63% and 60% inhibition) for V. parahaemolyticus at refrigerator and room temperatures, respectively. Moreover, acetic acid was more effective at room temperature than at refrigerator temperature. Concerning the effect of lemon juice (citric acid), it was more effective than acetic acid at short marination (0.25 and 1 h) at both temperatures for the two pathogens. Moreover, lemon was more effective at refrigerator temperature than at room temperature at the same aforementioned time. The difference between the reduction effects of the two acids on both pathogens was statistically significant (p<0.0001). Conclusion: Overall, the examined shrimp samples were found to be vectors for Vibrio and Aeromonas spp. Application of hygienic measures during handling and cooking of shrimp should be esteemed. The organic acid treatment trial showed that vinegar and lemon juice can be used as a safe and economic method to limit the microbial contamination in seafood.
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Affiliation(s)
- Hanaa Mohamed Fadel
- Department of Animal Hygiene and Zoonoses, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
| | - Maather M.M. El-Lamie
- Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
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16
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Li L, Gao M, Lu T, Gu D. RETRACTED: Dissection of ToxR-dependent and ToxR-independent stress-regulated pathways in Vibrio parahaemolyticus. Microbiol Res 2019; 223-225:79-87. [PMID: 31178055 DOI: 10.1016/j.micres.2019.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/20/2019] [Accepted: 03/29/2019] [Indexed: 12/28/2022]
Abstract
This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).
This article has been retracted at the request of the authors. After having been alerted by an anonymous reader the authors found out that in order to substantiate one of their conclusions (DeltaToxR-reduced killing activity is mediated via T6SS2) more experiments are needed. To avoid any potentially wrong conclusions being published, the authors decided to retract the article and to resubmit their manuscript once the additional experiments have been completed. The Editor-in-Chief agreed to the retraction. The authors wish to apologize for any inconvenience caused.
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Affiliation(s)
- Lingzhi Li
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety/Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Yangzhou University, Yangzhou, 225009, China
| | - Miaomiao Gao
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety/Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Yangzhou University, Yangzhou, 225009, China
| | - Tianyu Lu
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety/Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Yangzhou University, Yangzhou, 225009, China
| | - Dan Gu
- Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety/Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Yangzhou University, Yangzhou, 225009, China.
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17
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DeAngelis CM, Saul-McBeth J, Matson JS. Vibrio responses to extracytoplasmic stress. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:511-521. [PMID: 30246498 DOI: 10.1111/1758-2229.12693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 06/08/2023]
Abstract
A critical factor for bacterial survival in any environment is the ability to sense and respond appropriately to any stresses encountered. This is especially important for bacteria that inhabit environments that are constantly changing, or for those that inhabit more than one biological niche. Vibrio species are unique in that they are aquatic organisms, and must adapt to ever-changing temperatures, salinity levels and nutrient concentrations. In addition, many species of Vibrio colonize other organisms, and must also deal with components of the host immune response. Vibrio infections of humans and other organisms have become more common in recent years, due to increasing water temperatures in many parts of the world. Therefore, understanding how these ubiquitous marine bacteria adapt to their changing environments is of importance. In this review, we discuss some of the ways that Vibrios sense and respond to the variety of stresses that negatively affect the bacterial cell envelope. Specifically, we will focus on what is currently known about the σE response, the Cpx response and the contributions of OmpU to extracytoplasmic stress relief.
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Affiliation(s)
- Cara M DeAngelis
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
| | - Jessica Saul-McBeth
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
| | - Jyl S Matson
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
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18
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Sakib SN, Reddi G, Almagro-Moreno S. Environmental role of pathogenic traits in Vibrio cholerae. J Bacteriol 2018; 200:e00795-17. [PMID: 29581410 PMCID: PMC6040180 DOI: 10.1128/jb.00795-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Vibrio cholerae is a natural inhabitant of aquatic ecosystems. Some strains of V. cholerae can colonize the human host and cause cholera, a profuse watery diarrhea. The major pathogenicity factors and virulence regulators of V. cholerae are either encoded in mobile genetic elements acquired in the environment (e.g. pathogenicity islands or lysogenic phages) or in the core genome. Several lines of evidence indicate that the emergence of numerous virulence traits of V. cholerae occurred in its natural environment due to biotic and abiotic pressures. Here, we discuss the connection between the human host and the potential ecological role of these virulent traits. Unraveling these connections will help us understand the emergence of this organism and other facultative bacterial pathogens.
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Affiliation(s)
- S Nazmus Sakib
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32816, USA
| | - Geethika Reddi
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32816, USA
| | - Salvador Almagro-Moreno
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida 32816, USA.
- National Center for Integrated Coastal Research, University of Central Florida, Orlando, Florida 32816, USA
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19
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Zhang Y, Gao H, Osei-Adjei G, Zhang Y, Yang W, Yang H, Yin Z, Huang X, Zhou D. Transcriptional Regulation of the Type VI Secretion System 1 Genes by Quorum Sensing and ToxR in Vibrio parahaemolyticus. Front Microbiol 2017; 8:2005. [PMID: 29085350 PMCID: PMC5650642 DOI: 10.3389/fmicb.2017.02005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/29/2017] [Indexed: 12/26/2022] Open
Abstract
Vibrio parahaemolyticus, the leading cause of seafood-associated gastroenteritis, harbors two separate T6SSs on chromosomes 1 and 2, i.e., T6SS1 (VP1386-1420) and T6SS2 (VPA1025-1046). T6SS1 contains at least 7 putative operons: VP1386-1387, VP1388-1390, VP1392-1391, VP1393-1406, VP1400-1406, VP1409-1407, and VP1410-1420. V. parahaemolyticus AphA and OpaR are the two master regulators of quorum sensing (QS) system that are highly expressed at low cell density and high cell density, respectively. ToxR is a membrane-bound virulence regulatory protein conserved across the Vibrio family. In the present work, we show that ToxR coordinates with AphA and OpaR to repress T6SS1 expression in V. parahaemolyticus. OpaR binds to the promoters of VP1388-1390, VP1400-1406, and VP1409-1407 to repress their transcription, but it appears to negatively regulate VP1393-1406 transcription in an indirect manner. By contrast, AphA negatively regulated the above four T6SS1 operons in an indirect manner. In addition, ToxR binds to the promoters of VP1400-1406 and VP1409-1407 to inhibit their transcription, but it presents an indirect interaction with VP1388-1390 and VP1393-1406 promoters. Notably, the expression of ToxR also manifested in a QS-dependent manner and the highest expression occurred at LCD. Meanwhile, the highest expression of T6SS1 occurred at an OD600 value of 0.6 to 0.8 due to the tight regulation of ToxR and QS, suggesting T6SS1 functions only during the mid-logarithmic growth phase. These observations provide significant insight into the molecular mechanism of T6SS1 gene regulation by QS and ToxR in V. parahaemolyticus.
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Affiliation(s)
- Yiquan Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - He Gao
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, China
| | | | - Ying Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Wenhui Yang
- Department of Biosafety, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Huiying Yang
- Department of Biosafety, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhe Yin
- Department of Biosafety, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xinxiang Huang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Dongsheng Zhou
- Department of Biosafety, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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20
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Yen M, Camilli A. Mechanisms of the evolutionary arms race between Vibrio cholerae and Vibriophage clinical isolates. Int Microbiol 2017; 20:116-120. [PMID: 29446802 PMCID: PMC7114818 DOI: 10.2436/20.1501.01.292] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 09/30/2017] [Indexed: 11/15/2022]
Abstract
This review highlights recent findings on the evolutionary arms race between the causative agent of cholera Vibrio cholerae and virulent bacteriophages (phages) ICP1, ICP2, and ICP3 isolated from cholera patient stool samples. We discuss mechanisms of phage resistance such as a unique phage-inhibitory chromosomal island and mutations that affect phage receptor expression. We also discuss the molecular characterization of ICP1 and its unique CRISPR-Cas system, which it uses to combat the phage-inhibitory chromosomal island. The role of phages in the life cycle of V. cholerae has been increasingly recognized and investigated in the past decade. This article will review hypotheses as to how the predator-prey relationship may have an impact on infections within individuals and on the self-limiting nature of cholera epidemics. In addition, we put forth a strategy of using phages as an intervention to reduce household transmission of cholera within a community.
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Affiliation(s)
- Minmin Yen
- Department of Molecular Biology & Microbiology and Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Andrew Camilli
- Department of Molecular Biology & Microbiology and Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, MA 02111, USA
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21
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Midgett CR, Almagro-Moreno S, Pellegrini M, Taylor RK, Skorupski K, Kull FJ. Bile salts and alkaline pH reciprocally modulate the interaction between the periplasmic domains of Vibrio cholerae ToxR and ToxS. Mol Microbiol 2017; 105:258-272. [PMID: 28464377 DOI: 10.1111/mmi.13699] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2017] [Indexed: 12/31/2022]
Abstract
ToxR is a transmembrane transcription factor that is essential for virulence gene expression and human colonization by Vibrio cholerae. ToxR requires its operon partner ToxS, a periplasmic integral membrane protein, for full activity. These two proteins are thought to interact through their respective periplasmic domains, ToxRp and ToxSp. In addition, ToxR is thought to be responsive to various environmental cues, such as bile salts and alkaline pH, but how these factors influence ToxR is not yet understood. Using NMR and reciprocal pull down assays, we present the first direct evidence that ToxR and ToxS physically interact. Furthermore, using NMR and DSF, it was shown that the bile salts cholate and chenodeoxycholate interact with purified ToxRp and destabilize it. Surprisingly, bile salt destabilization of ToxRp enhanced the interaction between ToxRp and ToxSp. In contrast, alkaline pH, which is one of the factors that leads to ToxR proteolysis, decreased the interaction between ToxRp and ToxSp. Taken together, these data suggest a model whereby bile salts or other detergents destabilize ToxR, increasing its interaction with ToxS to promote full ToxR activity. Subsequently, as V. cholerae alkalinizes its environment in late stationary phase, the interaction between the two proteins decreases, allowing ToxR proteolysis to proceed.
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Affiliation(s)
| | - Salvador Almagro-Moreno
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32816, USA
| | - Maria Pellegrini
- Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA
| | - Ronald K Taylor
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Karen Skorupski
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - F Jon Kull
- Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA
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22
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Origins of pandemic Vibrio cholerae from environmental gene pools. Nat Microbiol 2016; 2:16240. [DOI: 10.1038/nmicrobiol.2016.240] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 10/27/2016] [Indexed: 11/08/2022]
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Abstract
Similar to other genera and species of bacteria, whole genomic sequencing has revolutionized how we think about and address questions of basic Vibrio biology. In this review we examined 36 completely sequenced and annotated members of the Vibrionaceae family, encompassing 12 different species of the genera Vibrio, Aliivibrio, and Photobacterium. We reconstructed the phylogenetic relationships among representatives of this group of bacteria by using three housekeeping genes and 16S rRNA sequences. With an evolutionary framework in place, we describe the occurrence and distribution of primary and alternative sigma factors, global regulators present in all bacteria. Among Vibrio we show that the number and function of many of these sigma factors differs from species to species. We also describe the role of the Vibrio-specific regulator ToxRS in fitness and survival. Examination of the biochemical capabilities was and still is the foundation of classifying and identifying new Vibrio species. Using comparative genomics, we examine the distribution of carbon utilization patterns among Vibrio species as a possible marker for understanding bacteria-host interactions. Finally, we discuss the significant role that horizontal gene transfer, specifically, the distribution and structure of integrons, has played in Vibrio evolution.
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Kazi MI, Conrado AR, Mey AR, Payne SM, Davies BW. ToxR Antagonizes H-NS Regulation of Horizontally Acquired Genes to Drive Host Colonization. PLoS Pathog 2016; 12:e1005570. [PMID: 27070545 PMCID: PMC4829181 DOI: 10.1371/journal.ppat.1005570] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/22/2016] [Indexed: 02/04/2023] Open
Abstract
The virulence regulator ToxR initiates and coordinates gene expression needed by Vibrio cholerae to colonize the small intestine and cause disease. Despite its prominence in V. cholerae virulence, our understanding of the direct ToxR regulon is limited to four genes: toxT, ompT, ompU and ctxA. Here, we determine ToxR’s genome-wide DNA-binding profile and demonstrate that ToxR is a global regulator of both progenitor genome-encoded genes and horizontally acquired islands that encode V. cholerae’s major virulence factors and define pandemic lineages. We show that ToxR shares more than a third of its regulon with the histone-like nucleoid structuring protein H-NS, and antagonizes H-NS binding at shared binding locations. Importantly, we demonstrate that this regulatory interaction is the critical function of ToxR in V. cholerae colonization and biofilm formation. In the absence of H-NS, ToxR is no longer required for V. cholerae to colonize the infant mouse intestine or for robust biofilm formation. We further illustrate a dramatic difference in regulatory scope between ToxR and other prominent virulence regulators, despite similar predicted requirements for DNA binding. Our results suggest that factors in addition to primary DNA structure influence the ability of ToxR to recognize its target promoters. The transcription factor ToxR initiates a virulence regulatory cascade required for V. cholerae to express essential host colonization factors and cause disease. Genome-wide expression studies suggest that ToxR regulates many genes important for V. cholerae pathogenesis, yet our knowledge of the direct regulon controlled by ToxR is limited to just four genes. Here, we determine ToxR’s genome-wide DNA-binding profile and show that ToxR is a global regulator of both progenitor genome-encoded genes and horizontally acquired islands that encode V. cholerae’s major virulence factors. Our results suggest that ToxR has gained regulatory control over important acquired elements that not only drive V. cholerae pathogenesis, but also define the major transitions of V. cholerae pandemic lineages. We demonstrate that ToxR shares more than a third of its regulon with the histone-like nucleoid structuring protein H-NS, and antagonizes H-NS for control of critical colonization functions. This regulatory interaction is the major role of ToxR in V. cholerae colonization, since deletion of hns abrogates the need for ToxR in V. cholerae host colonization. By comparing the genome-wide binding profiles of ToxR and other critical virulence regulators, we show that, despite similar predicted DNA binding requirements, ToxR is unique in its global control of progenitor-encoded and acquired genes. Our results suggest that factors in addition to primary DNA structure determine selection of ToxR binding sites.
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Affiliation(s)
- Misha I. Kazi
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Aaron R. Conrado
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Alexandra R. Mey
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
| | - Shelley M. Payne
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Bryan W. Davies
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of America
- Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Sakharwade SC, Mukhopadhaya A. Vibrio cholerae porin OmpU induces LPS tolerance by attenuating TLR-mediated signaling. Mol Immunol 2015; 68:312-24. [PMID: 26454478 DOI: 10.1016/j.molimm.2015.09.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/31/2022]
Abstract
Porins can act as pathogen-associated molecular patterns, can be recognized by the host immune system and modulate immune responses. Vibrio choleraeporin OmpU aids in bacterial survival in the human gut by increasing resistance against bile acids and anti-microbial peptides. V. choleraeOmpU is pro-inflammatory in nature. However, interestingly, it can also down-regulate LPS-mediated pro-inflammatory responses. In this study, we have explored how OmpU-pretreatment affects LPS-mediated responses. Our study indicates that OmpU-pretreatment followed by LPS-activation does not induce M2-polarization of macrophages/monocytes. Further, OmpU attenuates LPS-mediated TLR2/TLR6 signaling by decreasing the association of TLRs along with recruitment of MyD88 and IRAKs to the receptor complex. This results in decreased translocation of NFκB in the nucleus. Additionally, OmpU-pretreatment up-regulates expression of IRAK-M, a negative regulator of TLR signaling, in RAW 264.7 mouse macrophage cells upon LPS-stimulation. Suppressor cytokine IL-10 is partially involved in OmpU-induced down-regulation of LPS-mediated TNFα production in human PBMCs. Furthermore, OmpU-pretreatment also affects macrophage function, by enhancing phagocytosis in LPS-treated RAW 264.7 cells, and down-regulates LPS-induced cell surface expression of co-stimulatory molecules. Altogether, OmpU causes suppression of LPS-mediated responses by attenuating the LPS-mediated TLR signaling pathway.
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Affiliation(s)
- Sanica C Sakharwade
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Manauli, 140306 Punjab, India
| | - Arunika Mukhopadhaya
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Manauli, 140306 Punjab, India.
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Ante VM, Bina XR, Bina JE. The LysR-type regulator LeuO regulates the acid tolerance response in Vibrio cholerae. MICROBIOLOGY-SGM 2015; 161:2434-43. [PMID: 26424466 DOI: 10.1099/mic.0.000194] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Vibrio cholerae is a neutrophilic enteric pathogen that is extremely sensitive to acid. As V. cholerae passages through the host gastrointestinal tract it is exposed to a variety of environmental stresses including low pH and volatile fatty acids. Exposure to acidic environments induces expression of the V. cholerae acid tolerance response. A key component of the acid tolerance response is the cad system, which is encoded by cadC and the cadBA operon. CadB is a lysine/cadaverine antiporter and CadA is a lysine decarboxylase and these function together to counter low intracellular and extracellular pH. CadC is a membrane-associated transcription factor that activates cadBA expression in response to acidic conditions. Herein we investigated the role of the LysR-type transcriptional regulator LeuO in the V. cholerae acid tolerance response. Transcriptional reporter assays revealed that leuO expression repressed cadC transcription, indicating that LeuO was a cadC repressor. Consistent with this, leuO expression was inversely linked to lysine decarboxylase production and leuO overexpression resulted in increased sensitivity to organic acids. Overexpression of leuO in a cadA mutant potentiated killing by organic acids, suggesting that the function of leuO in the acid tolerance response extended beyond its regulation of the cad system. Collectively, these studies have identified a new physiological role for LeuO in V. cholerae acid tolerance.
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Affiliation(s)
- Vanessa M Ante
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - X Renee Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - James E Bina
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Almagro-Moreno S, Root MZ, Taylor RK. Role of ToxS in the proteolytic cascade of virulence regulator ToxR in Vibrio cholerae. Mol Microbiol 2015; 98:963-76. [PMID: 26316386 DOI: 10.1111/mmi.13170] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2015] [Indexed: 11/28/2022]
Abstract
Two of the primary virulence regulators of Vibrio cholerae, ToxR and TcpP, function together with cognate effector proteins. ToxR undergoes regulated intramembrane proteolysis (RIP) during late stationary phase in response to nutrient limitation at alkaline pH; however, the specific function of its cognate ToxS remains unresolved. In this work, we found that ToxR rapidly becomes undetectable in a ΔtoxS mutant when cultures are exposed to either starvation conditions or after alkaline pH shock individually. A ΔtoxS mutant enters into a dormant state associated with the proteolysis of ToxR at a faster rate than wild-type, closely resembling a ΔtoxR mutant. Using a mutant with a periplasmic substitution in ToxS, we found that the proteases DegS and DegP function additively with VesC and a novel protease, TapA, to degrade ToxR in the mutant. Overall, the results shown here reveal a role for ToxS in the stabilization of ToxR by protecting the virulence regulator from premature proteolysis.
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Affiliation(s)
- Salvador Almagro-Moreno
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Michael Z Root
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Ronald K Taylor
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
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Vibrio cholerae leuO Transcription Is Positively Regulated by ToxR and Contributes to Bile Resistance. J Bacteriol 2015; 197:3499-510. [PMID: 26303831 DOI: 10.1128/jb.00419-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/21/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Vibrio cholerae is an aquatic organism and facultative human pathogen that colonizes the small intestine. In the small intestine, V. cholerae is exposed to a variety of antimicrobial compounds, including bile. V. cholerae resistance to bile is multifactorial and includes alterations in the membrane permeability barrier that are mediated by ToxR, a membrane-associated transcription factor. ToxR has also been shown to be required for activation of the LysR family transcription factor leuO in response to cyclic dipeptides. LeuO has been implicated in the regulation of multiple V. cholerae phenotypes, including biofilm production and virulence. In this study, we investigated the effects of bile on leuO expression. We show that leuO transcription increased in response to bile and bile salts but not in response to other detergents. The bile-dependent increase in leuO expression was dependent on ToxR, which was found to bind directly to the leuO promoter. The periplasmic domain of ToxR was required for basal leuO expression and for the bile-dependent induction of both leuO and ompU transcription. V. cholerae mutants that did not express leuO exhibited increased bile susceptibility, suggesting that LeuO contributes to bile resistance. Our collective results demonstrate that ToxR activates leuO expression in response to bile and that LeuO is a component of the ToxR-dependent responses that contribute to bile resistance. IMPORTANCE The success of Vibrio cholerae as a human pathogen is dependent upon its ability to rapidly adapt to changes in its growth environment. Growth in the human gastrointestinal tract requires the expression of genes that provide resistance to host antimicrobial compounds, including bile. In this work, we show for the first time that the LysR family regulator LeuO mediates responses in V. cholerae that contribute to bile resistance.
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Chatterjee T, Mukherjee D, Banerjee M, Chatterjee BK, Chakrabarti P. Crystal structure and activity of protein L-isoaspartyl-O-methyltransferase from Vibrio cholerae, and the effect of AdoHcy binding. Arch Biochem Biophys 2015; 583:140-9. [PMID: 26255776 DOI: 10.1016/j.abb.2015.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/03/2015] [Accepted: 08/03/2015] [Indexed: 11/17/2022]
Abstract
The repair enzyme Protein L-isoaspartyl-O-methyltransferase (PIMT) is widely distributed in various organisms. PIMT catalyzes S-adenosylmethionine (AdoMet) dependent methylation of abnormal L-isoaspartyl residues, formed by the deamidation of asparagines and isomerization of aspartates. We report the crystal structure of PIMT of Vibrio cholerae (VcPIMT), the aetiological agent for cholera, complexed with the demethylated cofactor S-adenosyl-L-homocysteine (AdoHcy) to 2.05 Å resolution. A stretch of residues (39-58), lining the substrate-binding site, is disordered. Urea-induced unfolding free energy for apo and VcPIMT-AdoHcy complex reveals greater stability for the cofactor-bound protein. The kinetic parameters for the methyltransferase activity of the recombinant VcPIMT was determined using a continuous spectrophotometric color-based assay using the peptide substrate [VYP(L-isoD)HA]. The enzyme exhibited activity higher than the Escherichia coli enzyme and closer to those from thermophilic bacteria and the mammalian source. The association constant for substrate binding is 2.29 × 10(6) M(-1), quite similar to that for AdoHcy. The crystal structure and the model of the peptide-bound structure indicate that the majority of the interactions used for cofactor/substrate binding are provided by the main-chain atoms. Evolutionary relationships derived based on a phylogenetic tree constructed using the PIMT sequences are in conformity with the crystal structures of nine AdoHcy-bound PIMTs.
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Affiliation(s)
- Tanaya Chatterjee
- Department of Biochemistry, Bose Institute, P1/12, CIT Scheme VIIM, Kolkata 700054, India
| | - Debadrita Mukherjee
- Bioinformatics Centre, Bose Institute, P1/12, CIT Scheme VIIM, Kolkata 700054, India
| | - Mousumi Banerjee
- Department of Biotechnology, West Bengal University of Technology, Kolkata 700064, India
| | - Barun K Chatterjee
- Department of Physics, Bose Institute, 93/1APC Road, Kolkata 700009, India
| | - Pinak Chakrabarti
- Department of Biochemistry, Bose Institute, P1/12, CIT Scheme VIIM, Kolkata 700054, India; Bioinformatics Centre, Bose Institute, P1/12, CIT Scheme VIIM, Kolkata 700054, India.
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Varsaki A, Murphy C, Barczynska A, Jordan K, Carroll C. The acid adaptive tolerance response in Campylobacter jejuni induces a global response, as suggested by proteomics and microarrays. Microb Biotechnol 2015. [PMID: 26221965 PMCID: PMC4621450 DOI: 10.1111/1751-7915.12302] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Campylobacter jejuni CI 120 is a natural isolate obtained during poultry processing and has the ability to induce an acid tolerance response (ATR) to acid + aerobic conditions in early stationary phase. Other strains tested they did not induce an ATR or they induced it in exponential phase. Campylobacter spp. do not contain the genes that encode the global stationary phase stress response mechanism. Therefore, the aim of this study was to identify genes that are involved in the C. jejuni CI 120 early stationary phase ATR, as it seems to be expressing a novel mechanism of stress tolerance. Two-dimensional gel electrophoresis was used to examine the expression profile of cytosolic proteins during the C. jejuni CI 120 adaptation to acid + aerobic stress and microarrays to determine the genes that participate in the ATR. The results indicate induction of a global response that activated a number of stress responses, including several genes encoding surface components and genes involved with iron uptake. The findings of this study provide new insights into stress tolerance of C. jejuni, contribute to a better knowledge of the physiology of this bacterium and highlight the diversity among different strains.
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Affiliation(s)
- Athanasia Varsaki
- Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Caroline Murphy
- Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.,Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
| | - Alicja Barczynska
- Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Kieran Jordan
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
| | - Cyril Carroll
- Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
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Abstract
To cause the diarrheal disease cholera, Vibrio cholerae must effectively colonize the small intestine. In order to do so, the bacterium needs to successfully travel through the stomach and withstand the presence of agents such as bile and antimicrobial peptides in the intestinal lumen and mucus. The bacterial cells penetrate the viscous mucus layer covering the epithelium and attach and proliferate on its surface. In this review, we discuss recent developments and known aspects of the early stages of V. cholerae intestinal colonization and highlight areas that remain to be fully understood. We propose mechanisms and postulate a model that covers some of the steps that are required in order for the bacterium to efficiently colonize the human host. A deeper understanding of the colonization dynamics of V. cholerae and other intestinal pathogens will provide us with a variety of novel targets and strategies to avoid the diseases caused by these organisms.
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Affiliation(s)
- Salvador Almagro-Moreno
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
| | - Kali Pruss
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Ronald K. Taylor
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
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Almagro-Moreno S, Kim TK, Skorupski K, Taylor RK. Proteolysis of virulence regulator ToxR is associated with entry of Vibrio cholerae into a dormant state. PLoS Genet 2015; 11:e1005145. [PMID: 25849031 PMCID: PMC4388833 DOI: 10.1371/journal.pgen.1005145] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 03/16/2015] [Indexed: 12/20/2022] Open
Abstract
Vibrio cholerae O1 is a natural inhabitant of aquatic environments and causes the diarrheal disease, cholera. Two of its primary virulence regulators, TcpP and ToxR, are localized in the inner membrane. TcpP is encoded on the Vibrio Pathogenicity Island (VPI), a horizontally acquired mobile genetic element, and functions primarily in virulence gene regulation. TcpP has been shown to undergo regulated intramembrane proteolysis (RIP) in response to environmental conditions that are unfavorable for virulence gene expression. ToxR is encoded in the ancestral genome and is present in non-pathogenic strains of V. cholerae, indicating it has roles outside of the human host. In this study, we show that ToxR undergoes RIP in V. cholerae in response to nutrient limitation at alkaline pH, a condition that occurs during the stationary phase of growth. This process involves the site-2 protease RseP (YaeL), and is dependent upon the RpoE-mediated periplasmic stress response, as deletion mutants for the genes encoding these two proteins cannot proteolyze ToxR under nutrient limitation at alkaline pH. We determined that the loss of ToxR, genetically or by proteolysis, is associated with entry of V. cholerae into a dormant state in which the bacterium is normally found in the aquatic environment called viable but nonculturable (VBNC). Strains that can proteolyze ToxR, or do not encode it, lose culturability, experience a change in morphology associated with cells in VBNC, yet remain viable under nutrient limitation at alkaline pH. On the other hand, mutant strains that cannot proteolyze ToxR remain culturable and maintain the morphology of cells in an active state of growth. Overall, our findings provide a link between the proteolysis of a virulence regulator and the entry of a pathogen into an environmentally persistent state.
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Affiliation(s)
- Salvador Almagro-Moreno
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
| | - Tae K. Kim
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Karen Skorupski
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Ronald K. Taylor
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
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Taylor DL, Ante VM, Bina XR, Howard MF, Bina JE. Substrate-dependent activation of the Vibrio cholerae vexAB RND efflux system requires vexR. PLoS One 2015; 10:e0117890. [PMID: 25695834 PMCID: PMC4335029 DOI: 10.1371/journal.pone.0117890] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/05/2015] [Indexed: 01/08/2023] Open
Abstract
Vibrio cholerae encodes six resistance-nodulation-division (RND) efflux systems which function in antimicrobial resistance, virulence factor production, and intestinal colonization. Among the six RND efflux systems, VexAB exhibited broad substrate specificity and played a predominant role in intrinsic antimicrobial resistance. The VexAB system was encoded in an apparent three gene operon that included vexR; which encodes an uncharacterized TetR family regulator. In this work we examined the role of vexR in vexRAB expression. We found that VexR bound to the vexRAB promoter and vexR deletion resulted in decreased vexRAB expression and increased susceptibility to VexAB antimicrobial substrates. Substrate-dependent induction of vexRAB was dependent on vexR and episomal vexR expression provided a growth advantage in the presence of the VexAB substrate deoxycholate. The expression of vexRAB increased, in a vexR-dependent manner, in response to the loss of RND efflux activity. This suggested that VexAB may function to export intracellular metabolites. Support for this hypothesis was provided by data showing that vexRAB was upregulated in several metabolic mutants including tryptophan biosynthetic mutants that were predicted to accumulate indole. In addition, vexRAB was found to be upregulated in response to exogenous indole and to contribute to indole resistance. The collective results indicate that vexR is required for vexRAB expression in response to VexAB substrates and that the VexAB RND efflux system modulates the intracellular levels of metabolites that could otherwise accumulate to toxic levels.
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Affiliation(s)
- Dawn L. Taylor
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Vanessa M. Ante
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - X. Renee Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - Mondraya F. Howard
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
| | - James E. Bina
- University of Pittsburgh School of Medicine, Department of Microbiology and Molecular Genetics, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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AbuO, a TolC-like outer membrane protein of Acinetobacter baumannii, is involved in antimicrobial and oxidative stress resistance. Antimicrob Agents Chemother 2014; 59:1236-45. [PMID: 25512405 DOI: 10.1128/aac.03626-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although Acinetobacter baumannii is well accepted as a nosocomial pathogen, only a few of the outer membrane proteins (OMPs) have been functionally characterized. In this study, we demonstrate the biological functions of AbuO, a homolog of TolC from Escherichia coli. Inactivation of abuO led to increased sensitivity to high osmolarity and oxidative stress challenge. The ΔabuO mutant displayed increased susceptibility to antibiotics, such as amikacin, carbenicillin, ceftriaxone, meropenem, streptomycin, and tigecycline, and hospital-based disinfectants, such as benzalkonium chloride and chlorhexidine. The reverse transcription (RT)-PCR analysis indicated increased expression of efflux pumps (resistance nodulation cell division [RND] efflux pump acrD, 8-fold; SMR-type emrE homolog, 12-fold; and major facilitator superfamily [MFS]-type ampG homolog, 2.7-fold) and two-component response regulators (baeR, 4.67-fold; ompR, 10.43-fold) in the ΔabuO mutant together with downregulation of rstA (4.22-fold) and the pilin chaperone (9-fold). The isogenic mutant displayed lower virulence in a nematode model (P<0.01). Experimental evidence for the binding of MerR-type transcriptional regulator SoxR to radiolabeled abuO promoter suggests regulation of abuO by SoxR in A. baumannii.
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35
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Goulart CL, Bisch PM, von Krüger WMA, Homblé F. VCA1008: An Anion-Selective Porin of Vibrio Cholerae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:680-7. [PMID: 25462170 DOI: 10.1016/j.bbamem.2014.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/05/2014] [Accepted: 11/10/2014] [Indexed: 01/14/2023]
Abstract
A putative porin function has been assigned to VCA1008 of Vibrio cholerae. Its coding gene, vca1008, is expressed upon colonization of the small intestine in infant mice and human volunteers, and is essential for infection. In vitro, vca1008 is expressed under inorganic phosphate limitation and, in this condition, VCA1008 is the major outer membrane protein of the bacterium. Here, we provide the first functional characterization of VCA1008 reconstituted into planar lipid bilayers. Our main findings were: 1) VCA1008 forms an ion channel that, at high voltage (~±100 mV), presents a voltage-dependent activity and displays closures typical of trimeric porins, with a conductance of 4.28±0.04 nS (n=164) in 1M KCl; 2) It has a preferred selectivity for anions over cations; 3) Its conductance saturates with increasing inorganic phosphate concentration, suggesting VCA1008 contains binding site(s) for this anion; 4) Its ion selectivity is controlled by both fixed charged residues within the channel and diffusion along the pore; 5) Partitioning of poly (ethylene glycol)s (PEGs) of different molecular mass suggests that VCA1008 channel has a pore exclusion limit of 0.9 nm.
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Affiliation(s)
- Carolina L Goulart
- Structure et Fonction des Membranes Biologiques, Centre de Biologie Structurale et de Bioinformatique, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine (CP 206/2), B - 1050 Brussels, Belgium
| | - Paulo M Bisch
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Wanda M A von Krüger
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabrice Homblé
- Structure et Fonction des Membranes Biologiques, Centre de Biologie Structurale et de Bioinformatique, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine (CP 206/2), B - 1050 Brussels, Belgium.
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36
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The Vibrio cholerae Cpx envelope stress response senses and mediates adaptation to low iron. J Bacteriol 2014; 197:262-76. [PMID: 25368298 DOI: 10.1128/jb.01957-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Cpx pathway, a two-component system that employs the sensor histidine kinase CpxA and the response regulator CpxR, regulates crucial envelope stress responses across bacterial species and affects antibiotic resistance. To characterize the CpxR regulon in Vibrio cholerae, the transcriptional profile of the pandemic V. cholerae El Tor C6706 strain was examined upon overexpression of cpxR. Our data show that the Cpx regulon of V. cholerae is enriched in genes encoding membrane-localized and transport proteins, including a large number of genes known or predicted to be iron regulated. Activation of the Cpx pathway further led to the expression of TolC, the major outer membrane pore, and of components of two RND efflux systems in V. cholerae. We show that iron chelation, toxic compounds, or deletion of specific RND efflux components leads to Cpx pathway activation. Furthermore, mutations that eliminate the Cpx response or members of its regulon result in growth phenotypes in the presence of these inducers that, together with Cpx pathway activation, are partially suppressed by iron. Cumulatively, our results suggest that a major function of the Cpx response in V. cholerae is to mediate adaptation to envelope perturbations caused by toxic compounds and the depletion of iron.
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Seed KD, Yen M, Shapiro BJ, Hilaire IJ, Charles RC, Teng JE, Ivers LC, Boncy J, Harris JB, Camilli A. Evolutionary consequences of intra-patient phage predation on microbial populations. eLife 2014; 3:e03497. [PMID: 25161196 PMCID: PMC4141277 DOI: 10.7554/elife.03497] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The impact of phage predation on bacterial pathogens in the context of human disease is not currently appreciated. Here, we show that predatory interactions of a phage with an important environmentally transmitted pathogen, Vibrio cholerae, can modulate the evolutionary trajectory of this pathogen during the natural course of infection within individual patients. We analyzed geographically and temporally disparate cholera patient stool samples from Haiti and Bangladesh and found that phage predation can drive the genomic diversity of intra-patient V. cholerae populations. Intra-patient phage-sensitive and phage-resistant isolates were isogenic except for mutations conferring phage resistance, and moreover, phage-resistant V. cholerae populations were composed of a heterogeneous mix of many unique mutants. We also observed that phage predation can significantly alter the virulence potential of V. cholerae shed from cholera patients. We provide the first molecular evidence for predatory phage shaping microbial community structure during the natural course of infection in humans. DOI:http://dx.doi.org/10.7554/eLife.03497.001 Cholera epidemics occur seasonally in areas such as Bangladesh, and outbreaks can also strike in vulnerable regions, as has occurred recently in Haiti. The disease is caused by Vibrio cholerae, a water-borne bacterium that colonizes the small intestine, and its symptoms include severe diarrhea and vomiting which can lead to death if the patient is not treated promptly. Lytic phages are viruses that specifically attack and kill bacteria. After replicating many times inside the bacterial cell, the phages break open and destroy the cell. Over time a bacterial population can evolve to resist this phage ‘predation’; however, it is not known if bacterial pathogens need to defend themselves against phage attack when they infect humans. It had been suggested that phages might affect the progress of cholera infections in people, but molecular evidence that supports this hypothesis was lacking. When testing stool samples from Haitian cholera patients, Seed et al. found one sample contained a lot of lytic phage relative to the amount of V. cholerae present. This phage was very similar to—but distinct from—a phage found in Bangladeshi patients. The V. cholerae bacteria isolated from the stool sample were resistant to attack by the phage. Sequencing the genome of individual bacteria from this sample revealed that each had a mutation that made them resistant to the phage; and while many types of these mutations were found, these were the only differences between all the V. cholerae bacteria in this patient sample. This suggests that this resistance developed independently many different times within the patient due to strong selective pressure from phage predation. When Seed et al. looked at a phage-positive stool sample from a Bangladeshi patient, more mutations that made the bacteria resistant to this phage were found; however, these mutations were different again from the ones in the Haitian bacteria. Because of the nature of these mutations the bacteria from this patient were rendered unable to cause disease and non-transmissible. This work shows that phages can indeed have access to pathogenic bacteria during human infection. It also indicates that the pressure imposed by phage predation can, in some cases, be so strong that the bacteria lose their virulence and ability to spread to other humans in order to become resistant to the phage. DOI:http://dx.doi.org/10.7554/eLife.03497.002
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Affiliation(s)
- Kimberley D Seed
- Department of Molecular Biology and Microbiology, Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, United States
| | - Minmin Yen
- Department of Molecular Biology and Microbiology, Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, United States
| | - B Jesse Shapiro
- Département de sciences biologiques, Université de Montréal, Montreal, Canada
| | | | - Richelle C Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, United States Department of Medicine, Harvard Medical School, Boston, United States
| | - Jessica E Teng
- Partners In Health, Boston, United States Division of Global Health Equity, Brigham and Women's Hospital, Boston, United States
| | - Louise C Ivers
- Partners In Health, Boston, United States Division of Global Health Equity, Brigham and Women's Hospital, Boston, United States Department of Global Health and Social Medicine, Harvard Medical School, Boston, United States
| | - Jacques Boncy
- National Public Health Laboratory, Port-au-Prince, Haiti
| | - Jason B Harris
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, United States Department of Medicine, Harvard Medical School, Boston, United States Department of Pediatrics, Harvard Medical School, Boston, United States
| | - Andrew Camilli
- Department of Molecular Biology and Microbiology, Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, United States
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Lund P, Tramonti A, De Biase D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol Rev 2014; 38:1091-125. [PMID: 24898062 DOI: 10.1111/1574-6976.12076] [Citation(s) in RCA: 282] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/31/2022] Open
Abstract
As part of their life cycle, neutralophilic bacteria are often exposed to varying environmental stresses, among which fluctuations in pH are the most frequent. In particular, acid environments can be encountered in many situations from fermented food to the gastric compartment of the animal host. Herein, we review the current knowledge of the molecular mechanisms adopted by a range of Gram-positive and Gram-negative bacteria, mostly those affecting human health, for coping with acid stress. Because organic and inorganic acids have deleterious effects on the activity of the biological macromolecules to the point of significantly reducing growth and even threatening their viability, it is not unexpected that neutralophilic bacteria have evolved a number of different protective mechanisms, which provide them with an advantage in otherwise life-threatening conditions. The overall logic of these is to protect the cell from the deleterious effects of a harmful level of protons. Among the most favoured mechanisms are the pumping out of protons, production of ammonia and proton-consuming decarboxylation reactions, as well as modifications of the lipid content in the membrane. Several examples are provided to describe mechanisms adopted to sense the external acidic pH. Particular attention is paid to Escherichia coli extreme acid resistance mechanisms, the activity of which ensure survival and may be directly linked to virulence.
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Affiliation(s)
- Peter Lund
- School of Biosciences, University of Birmingham, Birmingham, UK
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Chiang ML, Chen HC, Wu C, Chen MJ. Effect of Acid Adaptation on the Environmental Stress Tolerance of Three Strains ofVibrio parahaemolyticus. Foodborne Pathog Dis 2014; 11:287-94. [DOI: 10.1089/fpd.2013.1641] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ming-Lun Chiang
- Department of Tourism and Hospitality, Kainan University, Taoyuan, Taiwan
| | - Hsi-Chia Chen
- Food and Drug Administration, Ministry of Health and Welfare, Taipei, Taiwan
| | - Chieh Wu
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Ming-Ju Chen
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
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Sakharwade SC, Sharma PK, Mukhopadhaya A. Vibrio cholerae porin OmpU induces pro-inflammatory responses, but down-regulates LPS-mediated effects in RAW 264.7, THP-1 and human PBMCs. PLoS One 2013; 8:e76583. [PMID: 24086753 PMCID: PMC3785423 DOI: 10.1371/journal.pone.0076583] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 08/25/2013] [Indexed: 12/18/2022] Open
Abstract
Vibrio cholerae porin OmpU plays a crucial role in the survival of the organism in the human gut. Various observations suggest critical involvement of OmpU in V. cholerae pathogenesis. However, OmpU is poorly characterized in terms of its ability to evoke cellular responses, particularly in the context of host immune system. Therefore, towards characterizing V. cholerae OmpU for its host immunomodulatory functions, we have studied the ability of OmpU to elicit pro-inflammatory responses in a range of immune cells which include, mouse RAW 264.7 macrophages, human THP-1 monocytes and human PBMCs. We have observed that purified OmpU induces pro-inflammatory responses in terms of production of NO, TNFα and IL-6. Interestingly, pre-treatment of the cells with OmpU suppresses the production of NO, TNFα, IL-6 as well as IL-12 upon subsequent activation with LPS. Our results therefore suggest that V. cholerae OmpU may have a differential regulatory role in terms of host immunomodulatory function: it can induce pro-inflammatory responses in target host immune cells, whereas it can also exert suppressive effect on LPS-induced pro-inflammatory responses. In addition, our study indicates that purified OmpU may have the ability to skew the Th1 response towards the Th2 response, presumably via suppression of IL-12 production.
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Affiliation(s)
- Sanica C Sakharwade
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India
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Vibrio cholerae VttR(A) and VttR(B) regulatory influences extend beyond the type 3 secretion system genomic island. J Bacteriol 2013; 195:2424-36. [PMID: 23524608 DOI: 10.1128/jb.02151-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subset of non-O1/non-O139 serogroup strains of Vibrio cholerae cause disease using type 3 secretion system (T3SS)-mediated mechanisms. An ∼50-kb genomic island carries genes encoding the T3SS structural apparatus, effector proteins, and two transmembrane transcriptional regulators, VttR(A) and VttR(B), which are ToxR homologues. Previous experiments demonstrated that VttR(A) and VttR(B) are necessary for colonization in vivo and promote bile-dependent T3SS gene expression in vitro. To better understand the scope of genes that are potential targets of VttR(A) and VttR(B) regulation, we performed deep RNA sequencing using O39 serogroup strain AM-19226 and derivatives carrying deletions in vttR(A) and vttR(B) grown in bile. Comparison of the transcript profiles from ΔvttR(A) and ΔvttR(B) mutant strains to the isogenic parent strain confirmed that VttR(A) and VttR(B) regulate expression of some T3SS island genes and provided additional information about relative expression levels and operon organization. Interestingly, the data also suggested that additional genes, located outside the T3SS island and encoding functions involved in motility, chemotaxis, type 6 secretion, transcriptional regulation, and stress responses, may also by regulated by VttR(A) and VttR(B). We verified transcript levels for selected genes by quantitative reverse transcription (RT)-PCR and then focused additional studies on motility and biofilm formation. The results suggest that VttR(A) and VttR(B) act as part of a complex transcriptional network that coordinates virulence gene expression with multiple cellular phenotypes. VttR(A) and VttR(B) therefore represent horizontally acquired transcriptional regulators with the ability to influence global gene expression in addition to modulating gene expression within the T3SS genomic island.
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Story RJ, Aziz AA, Mohamad SAS, Abdullah MFF. The adaptative acid tolerance of Shigella flexneri strain 307. 2012 IEEE COLLOQUIUM ON HUMANITIES, SCIENCE AND ENGINEERING (CHUSER) 2012. [DOI: 10.1109/chuser.2012.6504293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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Cheng C, Wakefield MJ, Yang J, Tauschek M, Robins-Browne RM. Genome-wide analysis of the Pho regulon in a pstCA mutant of Citrobacter rodentium. PLoS One 2012; 7:e50682. [PMID: 23226353 PMCID: PMC3511308 DOI: 10.1371/journal.pone.0050682] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/26/2012] [Indexed: 11/19/2022] Open
Abstract
The phosphate-specific transport operon, pstSCAB-phoU, of Gram-negative bacteria is an essential part of the Pho regulon. Its key roles are to encode a high-affinity inorganic phosphate transport system and to prevent activation of PhoB in phosphate-rich environments. In general, mutations in pstSCAB-phoU lead to the constitutive expression of the Pho regulon. Previously, we constructed a pstCA deletion mutant of Citrobacter rodentium and found it to be attenuated for virulence in mice, its natural host. This attenuation was dependent on PhoB or PhoB-regulated gene(s) because a phoB mutation restored virulence for mice to the pstCA mutant. To investigate how downstream genes may contribute to the virulence of C. rodentium, we used microarray analysis to investigate global gene expression of C. rodentium strain ICC169 and its isogenic pstCA mutant when grown in phosphate-rich medium. Overall 323 genes of the pstCA mutant were differentially expressed by at least 1.5-fold compared to the wild-type C. rodentium. Of these 145 were up-regulated and 178 were down-regulated. Differentially expressed genes included some involved in phosphate homoeostasis, cellular metabolism and protein metabolism. A large number of genes involved in stress responses and of unknown function were also differentially expressed, as were some virulence-associated genes. Up-regulated virulence-associated genes in the pstCA mutant included that for DegP, a serine protease, which appeared to be directly regulated by PhoB. Down-regulated genes included those for the production of the urease, flagella, NleG8 (a type III-secreted protein) and the tad focus (which encodes type IVb pili in Yersinia enterocolitica). Infection studies using C57/BL6 mice showed that DegP and NleG8 play a role in bacterial virulence. Overall, our study provides evidence that Pho is a global regulator of gene expression in C. rodentium and indicates the presence of at least two previously unrecognized virulence determinants of C. rodentium, namely, DegP and NleG8.
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Affiliation(s)
- Catherine Cheng
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Matthew J. Wakefield
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Genetics, The University of Melbourne, Parkville, Victoria, Australia
| | - Ji Yang
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Marija Tauschek
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Roy M. Robins-Browne
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
- Murdoch Childrens Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
- * E-mail:
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The Vibrio parahaemolyticus ToxRS regulator is required for stress tolerance and colonization in a novel orogastric streptomycin-induced adult murine model. Infect Immun 2012; 80:1834-45. [PMID: 22392925 DOI: 10.1128/iai.06284-11] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Vibrio parahaemolyticus, a marine bacterium, is the causative agent of gastroenteritis associated with the consumption of seafood. It contains a homologue of the toxRS operon that in V. cholerae is the key regulator of virulence gene expression. We examined a nonpolar mutation in toxRS to determine the role of these genes in V. parahaemolyticus RIMD2210633, an O3:K6 isolate, and showed that compared to the wild type, ΔtoxRS was significantly more sensitive to acid, bile salts, and sodium dodecyl sulfate stresses. We demonstrated that ToxRS is a positive regulator of ompU expression, and that the complementation of ΔtoxRS with ompU restores stress tolerance. Furthermore, we showed that ToxRS also regulates type III secretion system genes in chromosome I via the regulation of the leuO homologue VP0350. We examined the effect of ΔtoxRS in vivo using a new orogastric adult murine model of colonization. We demonstrated that streptomycin-treated adult C57BL/6 mice experienced prolonged intestinal colonization along the entire intestinal tract by the streptomycin-resistant V. parahaemolyticus. In contrast, no colonization occurred in non-streptomycin-treated mice. A competition assay between the ΔtoxRS and wild-type V. parahaemolyticus strains marked with the β-galactosidase gene lacZ demonstrated that the ΔtoxRS strain was defective in colonization compared to the wild-type strain. This defect was rescued by ectopically expressing ompU. Thus, the defect in stress tolerance and colonization in ΔtoxRS is solely due to OmpU. To our knowledge, the orogastric adult murine model reported here is the first showing sustained intestinal colonization by V. parahaemolyticus.
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Contribution of the lipopolysaccharide to resistance of Shigella flexneri 2a to extreme acidity. PLoS One 2011; 6:e25557. [PMID: 21984920 PMCID: PMC3184986 DOI: 10.1371/journal.pone.0025557] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 09/07/2011] [Indexed: 11/19/2022] Open
Abstract
Shigella flexneri is endemic in most underdeveloped countries, causing diarrheal disease and dysentery among young children. In order to reach its target site, the colon, Shigella must overcome the acid environment of the stomach. Shigella is able to persist in this stressful environment and, because of this ability it can initiate infection following the ingestion of very small inocula. Thus, acid resistance is considered an important virulence trait of this bacterium. It has been reported that moderate acid conditions regulate the expression of numerous components of the bacterial envelope. Because the lipopolysaccharide (LPS) is the major component of the bacterial surface, here we have addressed the role of LPS in acid resistance of S. flexneri 2a. Defined deletion mutants in genes encoding proteins involved in the synthesis, assembly and length regulation of the LPS O antigen were constructed and assayed for resistance to pH 2.5 after adaptation to pH 5.5. The results showed that a mutant lacking O antigen was significantly more sensitive to extreme acid conditions than the wild type. Not only the presence of polymerized O antigen, but also a particular polymer length (S-OAg) was required for acid resistance. Glucosylation of the O antigen also contributed to this property. In addition, a moderate acidic pH induced changes in the composition of the lipid A domain of LPS. The main modification was the addition of phosphoethanolamine to the 1' phosphate of lipid A. This modification increased resistance of S. flexneri to extreme acid conditions, provide that O antigen was produced. Overall, the results of this work point out to an important role of LPS in resistance of Shigella flexneri to acid stress.
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Abstract
The transcription factor Fur regulates the expression of a number of genes in Vibrio cholerae in response to changes in the level of available iron. Fur usually acts as a repressor, but here we show that Fur positively regulates the expression of ompT, which encodes a major outer membrane porin. OmpT levels increased when the bacteria were grown in medium containing relatively high levels of iron, and this effect required Fur. The level of ompT mRNA also is increased in the presence of iron and Fur. The effect of iron on OmpT levels was independent of the known ompT regulators ToxR and Crp, and it did not require RyhB, which has been shown to be responsible for positive regulation by iron of some V. cholerae genes. Electrophoretic mobility shift assays showed that Fur binds upstream of the ompT transcription start site in a region overlapping known binding sites for ToxR and Crp. These data suggest that Fur and iron positively regulate ompT expression through the direct binding of Fur to the ompT promoter.
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Ruwandeepika HAD, Defoirdt T, Bhowmick PP, Karunasagar I, Karunasagar I, Bossier P. In vitro and in vivo expression of virulence genes in Vibrio isolates belonging to the Harveyi clade in relation to their virulence towards gnotobiotic brine shrimp (Artemia franciscana). Environ Microbiol 2010; 13:506-17. [PMID: 20946530 DOI: 10.1111/j.1462-2920.2010.02354.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Vibrios belonging to the Harveyi clade are pathogenic marine bacteria affecting both vertebrates and invertebrates, thereby causing a severe threat to the aquaculture industry. In this study, the expression of haemolysin, metalloprotease, serine protease, the quorum sensing master regulator LuxR and the virulence regulator ToxR in different Harveyi clade isolates was measured with reverse transcriptase real-time PCR with specific primers. There was relatively low variation in the in vitro expression levels of the quorum sensing master regulator luxR (sevenfold), whereas for the other genes, the difference in expression between the isolates showing lowest and highest expression levels was over 25-fold. Furthermore, there was a significant correlation between expression levels of toxR and luxR and between the expression levels of these regulators and the protease genes. The expression levels of luxR, toxR and haemolysin were negatively correlated with the survival of brine shrimp larvae challenged with the isolates. Finally, a non-virulent, a moderately virulent and a strongly virulent isolate were selected to study in vivo expression of the virulence genes during infection of gnotobiotic brine shrimp larvae. The in vivo gene expression study showed a clear difference in virulence gene expression between both virulent isolates and the non-virulent isolate.
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Song T, Sabharwal D, Wai SN. VrrA mediates Hfq-dependent regulation of OmpT synthesis in Vibrio cholerae. J Mol Biol 2010; 400:682-8. [PMID: 20595045 DOI: 10.1016/j.jmb.2010.05.061] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/21/2010] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
OmpT, an outer membrane porin of Vibrio cholerae, is tightly regulated by the organism in response to different environments. Two transcriptional regulators, cAMP receptor protein (CRP) and ToxR, compete at the ompT promoter region. CRP activates ompT transcription by a loop-forming mechanism, while ToxR functions as an antiactivator and repressor, depending on its interplay with CRP. VrrA, a 140-nt small noncoding RNA in V. cholerae, is controlled by the alternative sigma factor sigma(E). We have demonstrated previously that VrrA represses ompA translation by base-pairing with the 5' region of the mRNA, thereby affecting the release of outer membrane vesicles and modulating the colonization ability of V. cholerae. In this study, we demonstrate that VrrA RNA represses ompT translation by base-pairing with the 5' region of the mRNA and that regulation requires the RNA chaperone protein Hfq. These results add new insight into the regulation of OmpT. In addition to pH/temperature signals via the ToxR regulon and carbon source signals via the cAMP-CRP complex, OmpT is further regulated by signals received via the sigma(E) regulon through VrrA.
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Affiliation(s)
- Tianyan Song
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden, Umeå Center for Microbial Research, Umeå University, SE-901 87 Umeå, Sweden
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Modulation of responses of Vibrio parahaemolyticus O3:K6 to pH and temperature stresses by growth at different salt concentrations. Appl Environ Microbiol 2010; 76:4720-9. [PMID: 20472729 DOI: 10.1128/aem.00474-10] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio parahaemolyticus inhabits marine, brackish, and estuarine waters worldwide, where fluctuations in salinity pose a constant challenge to the osmotic stress response of the organism. Vibrio parahaemolyticus is a moderate halophile, having an absolute requirement for salt for survival, and is capable of growth at 1 to 9% NaCl. It is the leading cause of seafood-related bacterial gastroenteritis in the United States and much of Asia. We determined whether growth in differing NaCl concentrations alters the susceptibility of V. parahaemolyticus O3:K6 to other environmental stresses. Vibrio parahaemolyticus was grown at a 1% or 3% NaCl concentration, and the growth and survival of the organism were examined under acid or temperature stress conditions. Growth of V. parahaemolyticus in 3% NaCl versus that in 1% NaCl increased survival under both inorganic (HCl) and organic (acetic acid) acid conditions. In addition, at 42 degrees C and -20 degrees C, 1% NaCl had a detrimental effect on growth. The expression of lysine decarboxylase (encoded by cadA), the organism's main acid stress response system, was induced by both NaCl and acid conditions. To begin to address the mechanism of regulation of the stress response, we constructed a knockout mutation in rpoS, which encodes the alternative stress sigma factor, and in toxRS, a two-component regulator common to many Vibrio species. Both mutant strains had significantly reduced survival under acid stress conditions. The effect of V. parahaemolyticus growth in 1% or 3% NaCl was examined using a cytotoxicity assay, and we found that V. parahaemolyticus grown in 1% NaCl was significantly more toxic than that grown in 3% NaCl.
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Pilonieta MC, Erickson KD, Ernst RK, Detweiler CS. A protein important for antimicrobial peptide resistance, YdeI/OmdA, is in the periplasm and interacts with OmpD/NmpC. J Bacteriol 2009; 191:7243-52. [PMID: 19767429 PMCID: PMC2786563 DOI: 10.1128/jb.00688-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 09/10/2009] [Indexed: 01/02/2023] Open
Abstract
Antimicrobial peptides (AMPs) kill or prevent the growth of microbes. AMPs are made by virtually all single and multicellular organisms and are encountered by bacteria in diverse environments, including within a host. Bacteria use sensor-kinase systems to respond to AMPs or damage caused by AMPs. Salmonella enterica deploys at least three different sensor-kinase systems to modify gene expression in the presence of AMPs: PhoP-PhoQ, PmrA-PmrB, and RcsB-RcsC-RcsD. The ydeI gene is regulated by the RcsB-RcsC-RcsD pathway and encodes a 14-kDa predicted oligosaccharide/oligonucleotide binding-fold (OB-fold) protein important for polymyxin B resistance in broth and also for virulence in mice. We report here that ydeI is additionally regulated by the PhoP-PhoQ and PmrA-PmrB sensor-kinase systems, which confer resistance to cationic AMPs by modifying lipopolysaccharide (LPS). ydeI, however, is not important for known LPS modifications. Two independent biochemical methods found that YdeI copurifies with OmpD/NmpC, a member of the trimeric beta-barrel outer membrane general porin family. Genetic analysis indicates that ompD contributes to polymyxin B resistance, and both ydeI and ompD are important for resistance to cathelicidin antimicrobial peptide, a mouse AMP produced by multiple cell types and expressed in the gut. YdeI localizes to the periplasm, where it could interact with OmpD. A second predicted periplasmic OB-fold protein, YgiW, and OmpF, another general porin, also contribute to polymyxin B resistance. Collectively, the data suggest that periplasmic OB-fold proteins can interact with porins to increase bacterial resistance to AMPs.
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Affiliation(s)
- M. Carolina Pilonieta
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Kimberly D. Erickson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Robert K. Ernst
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, University of Maryland-Baltimore, Department of Microbial Pathogenesis, School of Dentistry, Baltimore, Maryland 21201
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