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Halder M, Saha S, Mookerjee S, Palit A. Exploring the dynamics of toxigenic environmental Vibrio mimicus and its comparative analysis with Vibrio cholerae of the southern Gangetic delta. Arch Microbiol 2022; 204:420. [PMID: 35748957 DOI: 10.1007/s00203-022-03028-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 05/27/2022] [Accepted: 06/01/2022] [Indexed: 11/02/2022]
Abstract
Vibrio mimicus and Vibrio cholerae are closely related species. Environmental V.mimicus were comparatively analyzed with V.cholerae, for the presence of virulence genes, antibiotic susceptibility, resistance genes, in-vitro hemolysis, and biofilm formation. Phylogenetic analysis was performed depending on toxin-gene disposition and isolation area. One V.mimicus isolate harbored ctxA, tcp El-Tor, toxT and toxS, whereas several strains contained incomplete copies of virulence cassettes and associated toxin genes. V.cholerae isolates harbored ctx, tcp and toxT genes, with a higher preponderance of hlyA, rtxA and toxR genes. V.mimicus were highly sensitive to amino/carboxy-penicillins, furazolidone & gentamycin, with quinolone & tetracycline resistance genes. V.cholerae isolates were sensitive to penicillins and cephalosporins, with 29% of the strains bearing the sxt gene. Phylogenetically, the apomorphic strains of both species were unique to the inland sites. V.cholerae has embodied an enormous public health burden globally but our findings emphasize the role of V.mimicus as an emerging etiological agent with similar epidemic potential.
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Affiliation(s)
- Madhumanti Halder
- Division of Bacteriology, Indian Council of Medical Research- National Institute of Cholera & Enteric Diseases, P- 33, Scheme-XM, CIT Road, Beliaghata, Kolkata, 700 010, India
| | - Suvajit Saha
- Division of Bacteriology, Indian Council of Medical Research- National Institute of Cholera & Enteric Diseases, P- 33, Scheme-XM, CIT Road, Beliaghata, Kolkata, 700 010, India
| | - Subham Mookerjee
- Division of Bacteriology, Indian Council of Medical Research- National Institute of Cholera & Enteric Diseases, P- 33, Scheme-XM, CIT Road, Beliaghata, Kolkata, 700 010, India
| | - Anup Palit
- Division of Bacteriology, Indian Council of Medical Research- National Institute of Cholera & Enteric Diseases, P- 33, Scheme-XM, CIT Road, Beliaghata, Kolkata, 700 010, India.
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Zambelloni R, Marquez R, Roe AJ. Development of Antivirulence Compounds: A Biochemical Review. Chem Biol Drug Des 2014; 85:43-55. [DOI: 10.1111/cbdd.12430] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 08/20/2014] [Accepted: 08/26/2014] [Indexed: 01/09/2023]
Affiliation(s)
- Riccardo Zambelloni
- Institute of Infection Immunity and Inflammation; University of Glasgow; Sir Graeme Davies Building 120 University Place Glasgow G12 8TA UK
- Institute of Molecular and Cell Biology and Chemistry; University of Glasgow; Joseph Black Building Glasgow G12 8QQ UK
| | - Rudi Marquez
- Institute of Molecular and Cell Biology and Chemistry; University of Glasgow; Joseph Black Building Glasgow G12 8QQ UK
| | - Andrew J. Roe
- Institute of Molecular and Cell Biology and Chemistry; University of Glasgow; Joseph Black Building Glasgow G12 8QQ UK
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Shakhnovich EA, Sturtevant D, Mekalanos JJ. Molecular mechanisms of virstatin resistance by non-O1/non-O139 strains of Vibrio cholerae. Mol Microbiol 2007; 66:1331-41. [DOI: 10.1111/j.1365-2958.2007.05984.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Shakhnovich EA, Hung DT, Pierson E, Lee K, Mekalanos JJ. Virstatin inhibits dimerization of the transcriptional activator ToxT. Proc Natl Acad Sci U S A 2007; 104:2372-7. [PMID: 17283330 PMCID: PMC1892951 DOI: 10.1073/pnas.0611643104] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of antimicrobials is critical in this time of increasing antibiotic resistance of most clinically relevant bacteria. To date, all current antibiotics focus on inhibiting crucial enzymatic activities of their protein targets (i.e., trimethoprim for dihydrofolate reductase), thus disrupting in vitro essential gene functions. In contrast, we have previously reported the identification of virstatin, a small molecule that inhibits virulence regulation in Vibrio cholerae, thereby preventing intestinal colonization in an infant mouse model for cholera. Virstatin prevents expression of the two major V. cholerae virulence factors, cholera toxin (CT) and the toxin coregulated pilus, by inhibiting the virulence transcriptional activator ToxT. It has previously been described that the N-terminal domain of ToxT has the ability to form homodimers. We now demonstrate that virstatin inhibits ToxT dimerization, thus demonstrating that it further falls into a unique class of inhibitors that works by disrupting protein-protein interactions, particularly homodimerization. Using virstatin, truncation mutants of ToxT, and a virstatin-resistant mutant, we show that dimerization is required for ToxT activation of the ctx promoter. In contrast, ToxT dimerization does not appear to be required at all of the other ToxT-regulated promoters, suggesting multiple mechanisms may exist for its transcriptional activity.
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Affiliation(s)
- Elizabeth A. Shakhnovich
- *Department of Microbiology and Molecular Genetics, Harvard Medical School, Armenise Building, Room 425, 200 Longwood Avenue, Boston, MA 02115
| | - Deborah T. Hung
- *Department of Microbiology and Molecular Genetics, Harvard Medical School, Armenise Building, Room 425, 200 Longwood Avenue, Boston, MA 02115
- Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Simches Research Building 7208, 185 Cambridge Street, Boston, MA 02114
- Broad Institute of Massachusetts Institute of Technology and Harvard, 7 Cambridge Center, Cambridge, MA 02142; and
| | - Emily Pierson
- *Department of Microbiology and Molecular Genetics, Harvard Medical School, Armenise Building, Room 425, 200 Longwood Avenue, Boston, MA 02115
- Department of Molecular Biology, Center for Computational and Integrative Biology, Massachusetts General Hospital, Simches Research Building 7208, 185 Cambridge Street, Boston, MA 02114
- Broad Institute of Massachusetts Institute of Technology and Harvard, 7 Cambridge Center, Cambridge, MA 02142; and
| | - Kyungae Lee
- New England Regional Center of Excellence, 200 Longwood Avenue, Boston, MA 02114
| | - John J. Mekalanos
- *Department of Microbiology and Molecular Genetics, Harvard Medical School, Armenise Building, Room 425, 200 Longwood Avenue, Boston, MA 02115
- To whom correspondence should be addressed. E-mail:
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Rietsch A, Mekalanos JJ. Metabolic regulation of type III secretion gene expression in Pseudomonas aeruginosa. Mol Microbiol 2006; 59:807-20. [PMID: 16420353 PMCID: PMC2654213 DOI: 10.1111/j.1365-2958.2005.04990.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Type III secretion-mediated cytotoxicity is one of the key virulence mechanisms of the opportunistic pathogen Pseudomonas aeruginosa. Prior data from several laboratories have established that metabolism is a key factor in the regulation of type III secretion gene expression in P. aeruginosa. Here we use a fluorescence-activated cell sorter (FACS)-based approach to investigate expression of type III secretion genes at a single-cell level. The data demonstrate that the metabolic state regulates the percentage of cells that are able to induce type III secretion gene expression under inducing conditions. We also present evidence that this regulation is the result of an effect of the growth conditions on the ability of P. aeruginosa to assemble a functional type III secretion apparatus. Preliminary data suggest that the metabolite that controls type III secretion gene expression is derived from acetyl-CoA and that this regulation may, in part, be mediated by changes in the intracellular concentration of cyclic-AMP.
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Affiliation(s)
- Arne Rietsch
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave., Boston, MA 02115, USA
- Department of Molecular Biology and Microbiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - John J. Mekalanos
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave., Boston, MA 02115, USA
- For correspondence. E-mail ; Tel. (+1) 617 432 1935; Fax (+1) 617 738 7664
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Abstract
Vibrio cholerae is a Gram-negative bacterium that causes the acute diarrhoeal disease cholera. After the bacterium is ingested, it passes through the digestive tract, encountering various environmental stresses including the acidic milieu of the stomach and the toxic effects of bile in the duodenum. While these stresses serve as part of a host defence system, V. cholerae has evolved resistance mechanisms that allow it to evade these defences and establish infection. We examined the expression profiles of V. cholerae in response to bile or bile acids and found an induction of biofilm genes. We found that V. cholerae shows significantly enhanced biofilm formation in response to bile acids, and that bacteria within the biofilm are more resistant to the toxicity of bile acids compared with planktonic cells. Bile acid induction of biofilms was found to be dependent on the vps genes (Vibrio polysaccharide synthesis) and their transcriptional activator VpsR, but VpsT is not required. These results contribute to the developing picture of a complex relationship between V. cholerae and its environment within the host during infection.
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Affiliation(s)
- Deborah T Hung
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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Hung DT, Mekalanos JJ. Bile acids induce cholera toxin expression in Vibrio cholerae in a ToxT-independent manner. Proc Natl Acad Sci U S A 2005; 102:3028-33. [PMID: 15699331 PMCID: PMC549475 DOI: 10.1073/pnas.0409559102] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The production of cholera toxin (CT) during Vibrio cholerae infection results in the hallmark diarrhea that characterizes the disease cholera. The transmembrane protein ToxR was originally identified as a functional transcriptional activator of ctxAB in a heterologous Escherichia coli system. However, direct ToxR activation of the ctxAB promoter in V. cholerae has not been previously demonstrated. Instead, a regulatory cascade has been defined in which the activators ToxRS and TcpPH modulate ctxAB expression by acting in concert to transcriptionally activate another regulator, ToxT. ToxT, in turn, directly activates ctxAB expression as well as expression of the tcp genes and other virulence-associated genes. In this study, we show that ToxRS directly activates ctxAB in a ToxT-independent manner in a classical biotype V. cholerae, and that this activation requires the presence of bile acids. Although the levels of CT induced by this mechanism are lower than levels induced under other in vitro conditions, the bile-dependent conditions described here are more physiologic, being independent of pH and temperature. We further show that the inability of bile acids to stimulate ToxRS-dependent expression of CT in El Tor biotype strains is related to the differences between classical and El Tor ctxAB promoters, which differ in the number of heptad TTTTGAT repeats in their respective upstream regions. The ability of bile acids to stimulate direct activation of ctxAB by ToxRS depends upon the transmembrane domain of ToxR, which may interact with bile acids in the inner membrane of V. cholerae.
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Affiliation(s)
- Deborah T Hung
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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Davis BM, Moyer KE, Boyd EF, Waldor MK. CTX prophages in classical biotype Vibrio cholerae: functional phage genes but dysfunctional phage genomes. J Bacteriol 2000; 182:6992-8. [PMID: 11092860 PMCID: PMC94825 DOI: 10.1128/jb.182.24.6992-6998.2000] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CTXphi is a filamentous, lysogenic bacteriophage whose genome encodes cholera toxin, the primary virulence factor produced by Vibrio cholerae. CTX prophages in O1 El Tor and O139 strains of V. cholerae are found within arrays of genetically related elements integrated at a single locus within the V. cholerae large chromosome. The prophages of O1 El Tor and O139 strains generally yield infectious CTXphi. In contrast, O1 classical strains of V. cholerae do not produce CTXphi, although they produce cholera toxin and they contain CTX prophages integrated at two sites. We have identified the second site of CTX prophage integration in O1 classical strains and characterized the classical prophage arrays genetically and functionally. The genes of classical prophages encode functional forms of all of the proteins needed for production of CTXphi. Classical CTX prophages are present either as solitary prophages or as arrays of two truncated, fused prophages. RS1, a genetic element that is closely related to CTXphi and is often interspersed with CTX prophages in El Tor strains, was not detected in classical V. cholerae. Our model for CTXphi production predicts that the CTX prophage arrangements in classical strains will not yield extrachromosomal CTX DNA and thus will not yield virions, and our experimental results confirm this prediction. Thus, failure of O1 classical strains of V. cholerae to produce CTXphi is due to overall deficiencies in the structures of the arrays of classical prophages, rather than to mutations affecting individual CTX prophage genes.
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Affiliation(s)
- B M Davis
- Howard Hughes Medical Institute, Tufts University School of Medicine, and Division of Geographic Medicine and Infectious Diseases, New England Medical Center, Boston, Massachusetts 02111, USA
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Killeen K, Spriggs D, Mekalanos J. Bacterial mucosal vaccines: Vibrio cholerae as a live attenuated vaccine/vector paradigm. Curr Top Microbiol Immunol 1999; 236:237-54. [PMID: 9893363 DOI: 10.1007/978-3-642-59951-4_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- K Killeen
- Virus Research Institute, Cambridge, USA
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