Identification of a domain within the multifunctional
            <i>Vibrio cholerae</i>
            RTX toxin that covalently cross-links actin

Sheahan, Kerri-Lynn; Cordero, Christina L.; Satchell, K.J.F.

doi:10.1073/pnas.0401104101

Cited by 124 publications

(145 citation statements)

References 18 publications

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“…By analogy to T3SS and T4SS (21,22), the extracellular secretion of Hcp, VgrG-1, and VgrG-2 may actually reflect a more complex process that involves the translocation of these proteins by V. cholerae into eukaryotic target cells. Recently, Sheahan et al (23) reported that VgrG-1 and the V. cholerae RtxA toxin share a subdomain that mediates actin covalent crosslinking and cytotoxicity when expressed in the cytosol of mammalian cells. The extracellular cytotoxin RtxA, however, is not required for Dictyostelium virulence, because a rtxA mutant of V52 still kills amoebae (data not shown).…”

Section: Cholerae Uses the Vas Pathway To Mediate Virulence Towardmentioning

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.

1,030

1,334

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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: Cholerae Uses the Vas Pathway To Mediate Virulence Towardmentioning

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.

1,030

1,334

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“…Although all VgrG proteins are related to each other through several conserved domains (see below), VgrG-1 is unique in that it carries a C-terminal extension of 446-aa residues that shares extensive homology to the actin cross-linking domain (ACD) of the V. cholerae RtxA toxin (25) [see supporting information (SI) Fig. 6].…”

Section: Secretion Of Hcp Requiresmentioning

confidence: 99%

“…6]. Indeed, ectopic expression of the ACD from VgrG-1 inside eukaryotic cells was reported to cause cell rounding and covalent cross-linking of actin (25).…”

Section: Secretion Of Hcp Requiresmentioning

confidence: 99%

“…This analysis is preliminary at best and suffers from multiple limitations, most notably the inability to perform comparisons with proteins that do not yet have solved crystal structures. For example, although VgrG-1 is highly homologous to the RtxA toxin of V. cholerae in their shared ACD domains (25), PSIPRED predictions did not identify this homology because the ACD domain of RtxA has not yet been crystallized. Nonetheless, we performed this analysis to understand some of the diversity in function that might be represented by the C-terminal domains of evolved VgrG proteins (SI Table 1).…”

Section: Functional Predictions For Vgrg Proteins Encoded By Other Gram-mentioning

confidence: 99%

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Type VI secretion system translocates a phage tail spike-like protein into target cells where it cross-links actin

Pukatzki

Revel

et al. 2007

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

661

879

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Genes encoding type VI secretion systems (T6SS) are widely distributed in pathogenic Gram-negative bacterial species. In Vibrio cholerae, T6SS have been found to secrete three related proteins extracellularly, VgrG-1, VgrG-2, and VgrG-3. VgrG-1 can covalently cross-link actin in vitro, and this activity was used to demonstrate that V. cholerae can translocate VgrG-1 into macrophages by a T6SS-dependent mechanism. Protein structure search algorithms predict that VgrG-related proteins likely assemble into a trimeric complex that is analogous to that formed by the two trimeric proteins gp27 and gp5 that make up the baseplate ''tail spike'' of Escherichia coli bacteriophage T4. VgrG-1 was shown to interact with itself, VgrG-2, and VgrG-3, suggesting that such a complex does form. Because the phage tail spike protein complex acts as a membrane-penetrating structure as well as a conduit for the passage of DNA into phage-infected cells, we propose that the VgrG components of the T6SS apparatus may assemble a ''cellpuncturing device'' analogous to phage tail spikes to deliver effector protein domains through membranes of target host cells.bacteriophage ͉ cytotoxicity ͉ Vibrio cholerae ͉ virulence

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“…Recently, the V. cholerae rtxA toxin has been recognized as one the most potent cytotoxic toxins, which display actin cross-linking activities and are secreted to the bacterial exterior by the type I secretion systems (TISS) consisting of rtxB, rtxD and rtxE (14,20,21). Another group has shown V. vulnificus RTX toxin to be a multifunctional cytotoxin, which performs a central role in the pathogenesis of V. vulni ficus infectious disease.…”

Section: Comparative Analysis Of Proteins In the Culture Supernatantsmentioning

confidence: 99%

Comparative analysis of proteins in the culture supernatants of human intestinal epithelial cells infected with the wild-type and rtxE mutant of Vibrio vulnificus

Lee

Kim²,

Choi

et al. 2011

Int J Mol Med

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Abstract. Bacterial virulence factors and secreted extracellular proteins from damaged host cells following infection have been recognized as key mediators in the pathophysiological alterations observed in septic shock, and have also been shown to have a synergistic influence on bacterial pathogenicity. We hypothesized that during infections, virulence factors as well as host-shed proteins may synergistically influence aspects of the pathogenicity of V. vulnificus, such as primary septic shock and overproduction of proinflammatory cytokines. However, virulence factors and host-derived proteins have yet to be clearly evaluated during V. vulnificus infection. In this study, we analyzed and compared the proteins in conditioned supernatants generated from co-cultures of host cells and either wild-type or rtxE mutant V. vulnificus using LC-QTOF-MS/ MS analysis. In a previous study, we determined that the culture supernatants of the rtxE mutant V. vulnificus-infected INT-407 cells induced significantly lower levels of IL-8 production from human intestinal epithelial cells than did the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. LC-QTOF-MS/MS analysis results demonstrated that levels of proteins such as HSP90 α/β, 14-3-3 γ, PRX II, hnRNP K, β-actin, α-tubulin and V. vulnificus flagellin were significantly lower in the culture supernatants of rtxE mutant V. vulnificusinfected INT-407 cells than in the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. These results demonstrate that V. vulnificus RTX toxins acting via rtxE, a transporter of virulence factors, play a very important role in the pathogenesis of V. vulnificus, as well as in its initial role in inducing pathogenic mediators from host cells.

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Identification of a domain within the multifunctional Vibrio cholerae RTX toxin that covalently cross-links actin

Cited by 124 publications

References 18 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

Type VI secretion system translocates a phage tail spike-like protein into target cells where it cross-links actin

Comparative analysis of proteins in the culture supernatants of human intestinal epithelial cells infected with the wild-type and rtxE mutant of Vibrio vulnificus

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