Genomic characterization of non-O1, non-O139
            <i>Vibrio cholerae</i>
            reveals genes for a type III secretion system

Dziejman, Michelle; Serruto, Davide; Tam, Vincent C.; Sturtevant, Derek; Diraphat, Pornphan; Faruque, Shah M.; Rahman, Mustafizur; Heidelberg, John F.; Decker, Jeremy; Li, Li; Montgomery, Kate; Grills, George S.; Kucherlapati, Raju; Mekalanos, John J.

doi:10.1073/pnas.0409918102

Cited by 197 publications

(236 citation statements)

References 62 publications

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“…In L. pneumophila, these genes are nonessential components of the type IV secretion system (T4SS) required for cytotoxicity of L. pneumophila toward mammalian and D. discoideum cells (11,12). IcmF and IcmH (DotU) are thought to be accessory proteins that work in concert to improve the efficiency of T4SS translocation of bacterial effector proteins into the cytosol of eukaryotic target cells (13,14 (17), the V52 genome does not encode a T3SS other than the typical one required for flagella biosynthesis. Thus, it is also notable that no Dictyostelium-attenuated mutants were found in any gene known to be involved in flagellar biosynthesis.…”

Section: Resultsmentioning

confidence: 99%

Identification of a conserved bacterial protein secretion system in Vibrio cholerae using the Dictyostelium host model system

Pukatzki

Sturtevant

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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The bacterium Vibrio cholerae, like other human pathogens that reside in environmental reservoirs, survives predation by unicellular eukaryotes. Strains of the O1 and O139 serogroups cause cholera, whereas non-O1͞non-O139 strains cause human infections through poorly defined mechanisms. Using Dictyostelium discoideum as a model host, we have identified a virulence mechanism in a non-O1͞non-O139 V. cholerae strain that involves extracellular translocation of proteins that lack N-terminal hydrophobic leader sequences. Accordingly, we have named these genes ''VAS'' genes for virulence-associated secretion, and we propose that these genes encode a prototypic ''type VI'' secretion system. We show that vas genes are required for cytotoxicity of V. cholerae cells toward Dictyostelium amoebae and mammalian J774 macrophages by a contact-dependent mechanism. A large number of Gram-negative bacterial pathogens carry genes homologous to vas genes and potential effector proteins secreted by this pathway (i.e., hemolysin-coregulated protein and VgrG). Mutations in vas homologs in other bacterial species have been reported to attenuate virulence in animals and cultured macrophages. Thus, the genes encoding the VAS-related, type VI secretion system likely play an important conserved function in microbial pathogenesis and represent an additional class of targets for vaccine and antimicrobial drug-based therapies.Dictyostelium discoideum ͉ type VI secretion ͉ virulence-associated secretion C holera is a severe, life-threatening diarrheal disease caused by Vibrio cholerae strains of the O1 and O139 serogroups. In contrast, non-O1, non-O139 strains of V. cholerae are primarily associated with isolated cases of extra-intestinal infection or gastroenteritis. An exception to this pattern was a large outbreak of a cholera-like illness that occurred in 1968 in Sudan, where an O37 strain of V. cholerae caused 460 cases and 125 deaths (1). The virulence mechanisms of O1 and O139 strains involve the elaboration of extracellular factors such as cholera enterotoxin and toxin coregulated pili. In contrast, the virulence mechanisms used by non-O1, non-O139 strains remain poorly defined (2). Using the social amoeba Dictyostelium discoideum as a model host, we have developed an experimental system designed to identify novel virulence mechanisms from pathogenic non-O1, non-O139 strains.D. discoideum is a eukaryotic organism that seeks out and preys on bacteria through its phagocytic feeding behavior. As such, it has been used as a model eukaryotic cell that mimics a mammalian macrophage in aspects of its cell biology and interaction with microbes. Several environmental pathogenic bacteria, including Legionella pneumophila, Mycobacterium marinum, and Pseudomonas aeruginosa (3), resist Dictyostelium predation by producing factors that either kill amoebae or allow successful intracellular survival and multiplication. In these cases, the same virulence mechanisms operative against mammalian cells have also been implicated in resistance to Dictyosteli...

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Section: Resultsmentioning

confidence: 99%

Identification of a conserved bacterial protein secretion system in Vibrio cholerae using the Dictyostelium host model system

Pukatzki

Sturtevant

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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1,019

1,334

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“…A method that utilizes RFLP and a 59-be probe (Clark et al, 2000) is able to identify general conserved fragments between strains; however, specific MGCs differing between strains cannot be identified. When a microarray based on N16961 is used (Dziejman et al, 2005), only comparisons with N16961 can be made, and only MGCs present in N16961 and absent in the tested strain can be identified. Thus, the ability of the method described here to identify the presence or absence of specific gene cassettes has applications in evaluating the MGC pool available to V. cholerae.…”

Section: Discussionmentioning

confidence: 99%

Use of chromosomal integron arrays as a phylogenetic typing system for Vibrio cholerae pandemic strains

et al. 2007

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Approximately 200 serogroups of Vibrio cholerae exist, with only two, O1 and O139, responsible for epidemic and pandemic cholera. Strains from these serogroups have evolved from a common progenitor, with lateral gene transfer largely driving their emergence. These strains are so closely related that separation using single-or multi-locus phylogeny has proven difficult. V. cholerae strains contain a genetic system called the integron that is located in the chromosome and that can integrate and excise DNA elements called mobile gene cassettes (MGCs) by site-specific recombination. Large arrays of MGCs are found in V. cholerae strains. For instance, the O1 El Tor strain N16961 contains 179 MGCs. Since integron arrays are dynamic through recombination and excision of MGCs, it was hypothesized that the MGC composition in a given V. cholerae pandemic strain would be useful as a phylogenetic typing system. To address this, a PCR-based method was used to rapidly characterize the MGC composition of V. cholerae arrays. The results showed that the MGC composition of pandemic V. cholerae cassette arrays is relatively conserved, providing further evidence that these strains have evolved from a common progenitor. Comparison of MGC composition between the V. cholerae pandemic strains was also able to resolve the evolution of O139 from a subgroup of O1 El Tor. This level of differentiation of closely related V. cholerae isolates was more sensitive than conventional single-gene phylogeny or multi-locus sequence analysis. Using this method, novel MGCs from an O1 classical strain and an Argentinian O139 isolate were also identified, and a major deletion in the MGC array in all pandemic O139 strains and a subset of O1 El Tor strains was identified. Analysis of sequenced V. cholerae integron arrays showed that their evolution can proceed by rearrangements and deletions/insertions of large portions of MGCs in addition to the insertion or excision of single MGCs.

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“…This hemolysis is called the Kanagawa phenomenon and is considered a useful marker for identifi cation of pathogenic strains. Recently, TTSS genes related to the TTSS2 cluster were reported in clinical and environmental non-O1, non-O139 V. cholerae strains (14).…”

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confidence: 99%

Epidemiology ofVibrio parahaemolyticusOutbreaks, Southern Chile

Harth

Matsuda²,

Hernández³

et al. 2009

Emerg. Infect. Dis.

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Disease outbreaks caused by Vibrio parahaemolyticus in Puerto Montt, Chile, began in 2004 and reached a peak in 2005 at 3,600 clinical cases. Until 2006, every analyzed case was caused by the serovar O3:K6 pandemic strain. In the summer of 2007, only 475 cases were reported; 73% corresponded to the pandemic strain. This decrease was associated with a change in serotype of many pandemic isolates to O3:K59 and the emergence of new clinical strains. One of these strains, associated with 11% of the cases, was genotypically different from the pandemic strain but contained genes that were identical to those found on its pathogenicity island. These fi ndings suggest that pathogenicity-related genes were laterally transferred from the pandemic strain to one of the different V. parahaemolyticus groups comprising the diverse and shifting bacterial population in shellfi sh in this region.

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Genomic characterization of non-O1, non-O139 Vibrio cholerae reveals genes for a type III secretion system

Cited by 197 publications

References 62 publications

Identification of a conserved bacterial protein secretion system in Vibrio cholerae using the Dictyostelium host model system

Identification of a conserved bacterial protein secretion system in Vibrio cholerae using the Dictyostelium host model system

Use of chromosomal integron arrays as a phylogenetic typing system for Vibrio cholerae pandemic strains

Epidemiology ofVibrio parahaemolyticusOutbreaks, Southern Chile

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