This page has only limited features, please log in for full access.
Mounting evidence suggests that Type 3 Secretion Systems (T3SS) are widespread among Vibrio species, and are present in strains isolated from diverse sources such as human clinical infections, environmental reservoirs, and diseased marine life. Experiments evaluating Vibrio parahaemolyticus and Vibrio cholerae T3SS mediated virulence suggest that Vibrio T3SS pathogenicity islands have a tripartite composition. A conserved ‘core’ region encodes functions essential for colonization and disease in vivo, including modulation of innate immune signaling pathways and actin dynamics, whereas regions flanking core sequences are variable among strains and encode effector proteins performing a diverse array of activities. Characterizing novel functions associated with Vibrio-specific effectors is, therefore, essential for understanding how vibrios employ T3SS mechanisms to cause disease in a broad range of hosts and how T3SS island composition potentially defines species-specific disease.
Kelly A Miller; Katharine F Tomberlin; Michelle Dziejman. Vibrio variations on a type three theme. Current Opinion in Microbiology 2019, 47, 66 -73.
AMA StyleKelly A Miller, Katharine F Tomberlin, Michelle Dziejman. Vibrio variations on a type three theme. Current Opinion in Microbiology. 2019; 47 ():66-73.
Chicago/Turabian StyleKelly A Miller; Katharine F Tomberlin; Michelle Dziejman. 2019. "Vibrio variations on a type three theme." Current Opinion in Microbiology 47, no. : 66-73.
AM‐19226 is a pathogenic, non‐O1/non‐O139 serogroup strain of Vibrio cholerae that uses a Type 3 Secretion System (T3SS) mediated mechanism to colonize host tissues and disrupt homeostasis, causing cholera. Co‐culturing the Caco2‐BBE human intestinal epithelial cell line with AM‐19226 in the presence of bile results in rapid mammalian cell death that requires a functional T3SS. We examined the role of bile, sought to identify the mechanism, and evaluated the contributions of T3SS translocated effectors in in vitro cell death. Our results suggest that Caco2‐BBE cytotoxicity does not proceed by apoptotic or necrotic mechanisms, but rather displays characteristics consistent with osmotic lysis. Cell death was preceded by disassembly of epithelial junctions and reorganization of the cortical membrane skeleton, although neither cell death nor cell‐cell disruption required VopM or VopF, two effectors known to alter actin dynamics. Using deletion strains, we identified a subset of AM‐19226 Vops that are required for host cell death, which were previously assigned roles in protein translocation and colonization, suggesting that they function other than to promote cytotoxicity. The collective results therefore suggest that cooperative Vop activities are required to achieve cytotoxicity in vitro, or alternatively, that translocon pores destabilize the membrane in a bile dependent manner.
Kelly A. Miller; Mudit Chaand; Stacy Gregoire; Takeshi Yoshida; Lisa A. Beck; Andrei I. Ivanov; Michelle Dziejman. Characterization ofV.choleraeT3SS-dependent cytotoxicity in cultured intestinal epithelial cells. Cellular Microbiology 2016, 18, 1857 -1870.
AMA StyleKelly A. Miller, Mudit Chaand, Stacy Gregoire, Takeshi Yoshida, Lisa A. Beck, Andrei I. Ivanov, Michelle Dziejman. Characterization ofV.choleraeT3SS-dependent cytotoxicity in cultured intestinal epithelial cells. Cellular Microbiology. 2016; 18 (12):1857-1870.
Chicago/Turabian StyleKelly A. Miller; Mudit Chaand; Stacy Gregoire; Takeshi Yoshida; Lisa A. Beck; Andrei I. Ivanov; Michelle Dziejman. 2016. "Characterization ofV.choleraeT3SS-dependent cytotoxicity in cultured intestinal epithelial cells." Cellular Microbiology 18, no. 12: 1857-1870.
Genes carried on the type 3 secretion system (T3SS) pathogenicity island of Vibrio cholerae non-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affecting in vitro cell death, including bacterial load and the role of three transmembrane transcriptional regulatory proteins, VttR A , VttR B , and ToxR. VttR A and VttR B are encoded on the horizontally acquired T3SS genomic island, whereas ToxR is encoded on the ancestral chromosome. While strains carrying deletions in any one of the three transcriptional regulatory genes are unable to cause eukaryotic cell death, the results of complementation studies point to a hierarchy of regulatory control that converges on vttR B expression. The data suggest both that ToxR and VttR A act upstream of VttR B and that modifying the level of either vttR A or vttR B expression can strongly influence T3SS gene expression. We therefore propose a model whereby T3SS activity and, hence, in vitro cytotoxicity are ultimately regulated by vttR B expression. IMPORTANCE In contrast to O1 and O139 serogroup V. cholerae strains that cause cholera using two main virulence factors (toxin-coregulated pilus [TCP] and cholera toxin [CT]), O39 serogroup strain AM-19226 uses a type 3 secretion system as its principal virulence mechanism. Although the regulatory network governing TCP and CT expression is well understood, the factors influencing T3SS-associated virulence are not. Using an in vitro mammalian cell model to investigate the role of three ToxR-like transmembrane transcriptional activators in causing T3SS-dependent cytotoxicity, we found that expression levels and a hierarchical organization were important for promoting T3SS gene expression. Furthermore, our results suggest that horizontally acquired, ToxR-like proteins act in concert with the ancestral ToxR protein to orchestrate T3SS-mediated pathogenicity.
Kelly A. Miller; Madeline K. Sofia; Jacob W. A. Weaver; Christopher H. Seward; Michelle Dziejman. Regulation by ToxR-Like Proteins Converges on vttR B Expression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae. Journal of Bacteriology 2016, 198, 1675 -1682.
AMA StyleKelly A. Miller, Madeline K. Sofia, Jacob W. A. Weaver, Christopher H. Seward, Michelle Dziejman. Regulation by ToxR-Like Proteins Converges on vttR B Expression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae. Journal of Bacteriology. 2016; 198 (11):1675-1682.
Chicago/Turabian StyleKelly A. Miller; Madeline K. Sofia; Jacob W. A. Weaver; Christopher H. Seward; Michelle Dziejman. 2016. "Regulation by ToxR-Like Proteins Converges on vttR B Expression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae." Journal of Bacteriology 198, no. 11: 1675-1682.
Most pathogenic, non-O1/non-O139 serogroup Vibrio cholerae strains cause diarrheal disease in the absence of cholera toxin. Instead, many use Type 3 Secretion System (T3SS) mediated mechanisms to disrupt host cell homeostasis. We identified a T3SS effector protein, VopX, which is translocated into mammalian cells during in vitro co-culture. In a S. cerevisiae model system, we found that expression of VopX resulted in a severe growth defect that was partially suppressed by a deletion of RLM1, encoding the terminal transcriptional regulator of the Cell Wall Integrity MAP kinase (CWI) regulated pathway. Growth of yeast cells in the presence of sorbitol also suppressed the defect, supporting a role for VopX in destabilizing the cell wall. Expression of VopX activated expression of β-galactosidase from an RLM1-reponsive element reporter fusion, but failed to do so in cells lacking MAP kinases upstream of Rlm1. The results suggest that VopX inhibits cell growth by stimulating the CWI pathway through Rlm1. Rlm1 is an ortholog of mammalian MEF2 transcription factors that are proposed to regulate cell differentiation, proliferation, and apoptosis. The collective findings suggest that VopX contributes to disease by activating MAP kinase cascades that elicit changes in cellular transcriptional programs.
Christopher H. Seward; Alexander Manzella; Ashfaqul Alam; J. Scott Butler; Michelle Dziejman. Using S. cerevisiae as a Model System to Investigate V. cholerae VopX-Host Cell Protein Interactions and Phenotypes. Toxins 2015, 7, 4099 -4110.
AMA StyleChristopher H. Seward, Alexander Manzella, Ashfaqul Alam, J. Scott Butler, Michelle Dziejman. Using S. cerevisiae as a Model System to Investigate V. cholerae VopX-Host Cell Protein Interactions and Phenotypes. Toxins. 2015; 7 (10):4099-4110.
Chicago/Turabian StyleChristopher H. Seward; Alexander Manzella; Ashfaqul Alam; J. Scott Butler; Michelle Dziejman. 2015. "Using S. cerevisiae as a Model System to Investigate V. cholerae VopX-Host Cell Protein Interactions and Phenotypes." Toxins 7, no. 10: 4099-4110.
Vibrio cholerae is a genetically diverse species, and pathogenic strains can encode different virulence factors that mediate colonization and secretory diarrhea. Although the toxin-coregulated pilus (TCP) is the primary colonization factor in epidemic-causing V. cholerae strains, other strains do not encode the TCP and instead promote colonization via the activity of a type 3 secretion system (T3SS). Using the infant mouse model and T3SS-positive O39 serogroup strain AM-19226, we sought to determine which of 12 previously identified, T3SS-translocated proteins (Vops) are important for host colonization. We constructed in-frame deletions in each of the 12 loci in strain AM-19226 and identified five Vop deletion strains, including ΔVopM, which were severely attenuated for colonization. Interestingly, a subset of deletion strains was also incompetent for effector protein transport. Our collective data therefore suggest that several translocated proteins may also function as components of the structural apparatus or translocation machinery and indicate that while VopM is critical for establishing an infection, the combined activities of other effectors may also contribute to the ability of T3SS-positive strains to colonize host epithelial cell surfaces.
Mudit Chaand; Kelly A. Miller; Madeline K. Sofia; Cory Schlesener; Jacob W. A. Weaver; Vibha Sood; Michelle Dziejman. Type Three Secretion System Island-Encoded Proteins Required for Colonization by Non-O1/Non-O139 Serogroup Vibrio cholerae. Infection and Immunity 2015, 83, 2862 -2869.
AMA StyleMudit Chaand, Kelly A. Miller, Madeline K. Sofia, Cory Schlesener, Jacob W. A. Weaver, Vibha Sood, Michelle Dziejman. Type Three Secretion System Island-Encoded Proteins Required for Colonization by Non-O1/Non-O139 Serogroup Vibrio cholerae. Infection and Immunity. 2015; 83 (7):2862-2869.
Chicago/Turabian StyleMudit Chaand; Kelly A. Miller; Madeline K. Sofia; Cory Schlesener; Jacob W. A. Weaver; Vibha Sood; Michelle Dziejman. 2015. "Type Three Secretion System Island-Encoded Proteins Required for Colonization by Non-O1/Non-O139 Serogroup Vibrio cholerae." Infection and Immunity 83, no. 7: 2862-2869.
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 Δ vttR A and Δ vttR 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.
Mudit Chaand; Michelle Dziejman. Vibrio cholerae VttR A and VttR B Regulatory Influences Extend beyond the Type 3 Secretion System Genomic Island. Journal of Bacteriology 2013, 195, 2424 -2436.
AMA StyleMudit Chaand, Michelle Dziejman. Vibrio cholerae VttR A and VttR B Regulatory Influences Extend beyond the Type 3 Secretion System Genomic Island. Journal of Bacteriology. 2013; 195 (10):2424-2436.
Chicago/Turabian StyleMudit Chaand; Michelle Dziejman. 2013. "Vibrio cholerae VttR A and VttR B Regulatory Influences Extend beyond the Type 3 Secretion System Genomic Island." Journal of Bacteriology 195, no. 10: 2424-2436.
Numerous virulence factors have been associated with pathogenic non-O1/non-O139 serogroup strains ofVibrio cholerae. Among them are thethermostabledirecthemolysin (TDH) and theTDH-relatedhemolysin (TRH), which share amino acid similarities to the TDH and TRH proteins ofVibrio parahaemolyticus, where they have been shown to contribute to pathogenesis. Although TDH and TRH homologs can be encoded on extrachromosomal elements inV. cholerae, type III secretion system (T3SS)-positive strains, such as AM-19226, carry a copy oftrhwithin the T3SS genomic island. Transcriptional fusion analysis showed that in strain AM-19226,trhexpression is regulated in a bile-dependent manner by a family of transmembrane transcriptional regulators that includes VttRA, VttRB, and ToxR. Genes encoding T3SS structural components are expressed under similar conditions, suggesting that within the T3SS genomic island, genes encoding proteins unrelated to the T3SS and loci involved in T3SS synthesis are coregulated. Despite similarin vitroexpression patterns, however, TRH is not required for AM-19226 to colonize the infant mouse intestine, nor does it contribute to bile-mediated cytotoxicity when strain AM-19226 is cocultured with the mammalian cell line Caco2-BBE. Instead, we found that a functional T3SS is essential for AM-19226 to induce bile-mediated cytotoxicityin vitro. Collectively, the results are consistent with a more minor role for theV. choleraeTRH in T3SS-positive strains compared to the functions attributed to theV. parahaemolyticusTDH and TRH proteins.
Kelly A. Miller; Elaine Hamilton; Michelle Dziejman. The Vibrio cholerae trh Gene Is Coordinately RegulatedIn Vitrowith Type III Secretion System Genes by VttRA/VttRBbut Does Not Contribute to Caco2-BBE Cell Cytotoxicity. Infection and Immunity 2012, 80, 4444 -4455.
AMA StyleKelly A. Miller, Elaine Hamilton, Michelle Dziejman. The Vibrio cholerae trh Gene Is Coordinately RegulatedIn Vitrowith Type III Secretion System Genes by VttRA/VttRBbut Does Not Contribute to Caco2-BBE Cell Cytotoxicity. Infection and Immunity. 2012; 80 (12):4444-4455.
Chicago/Turabian StyleKelly A. Miller; Elaine Hamilton; Michelle Dziejman. 2012. "The Vibrio cholerae trh Gene Is Coordinately RegulatedIn Vitrowith Type III Secretion System Genes by VttRA/VttRBbut Does Not Contribute to Caco2-BBE Cell Cytotoxicity." Infection and Immunity 80, no. 12: 4444-4455.
AM-19226 is a pathogenic O39 serogroup Vibrio cholerae strain that lacks the typical virulence factors for colonization (toxin-coregulated pilus [TCP]) and toxin production (cholera toxin [CT]) and instead encodes a type III secretion system (T3SS). The mechanism of pathogenesis is unknown, and few effector proteins have been identified. We therefore undertook a survey of the open reading frames (ORFs) within the ∼49.7-kb T3SS genomic island to identify potential effector proteins. We identified 15 ORFs for their ability to inhibit growth when expressed in yeast and then used a β-lactamase (TEM1) fusion reporter system to demonstrate that 11 proteins were bona fide effectors translocated into HeLa cells in vitro in a T3SS-dependent manner. One effector, which we named VopX (A33_1663), is conserved only in V. cholerae and Vibrio parahaemolyticus T3SS-positive strains and has not been previously studied. A vopX deletion reduces the ability of strain AM-19226 to colonize in vivo , and the bile-induced expression of a vopX-lacZ transcriptional fusion in vitro is regulated by the T3SS-encoded transcriptional regulators VttR A and VttR B . An RLM1 yeast deletion strain rescued the growth inhibition induced by VopX expression, suggesting that VopX interacts with components of the cell wall integrity mitogen-activated protein kinase (MAPK) pathway. The collective results show that the V. cholerae T3SS encodes multiple effector proteins, one of which likely has novel activities that contribute to disease via interference with eukaryotic signaling pathways.
Ashfaqul Alam; Kelly A. Miller; Mudit Chaand; J. Scott Butler; Michelle Dziejman. Identification of Vibrio cholerae Type III Secretion System Effector Proteins. Infection and Immunity 2011, 79, 1728 -1740.
AMA StyleAshfaqul Alam, Kelly A. Miller, Mudit Chaand, J. Scott Butler, Michelle Dziejman. Identification of Vibrio cholerae Type III Secretion System Effector Proteins. Infection and Immunity. 2011; 79 (4):1728-1740.
Chicago/Turabian StyleAshfaqul Alam; Kelly A. Miller; Mudit Chaand; J. Scott Butler; Michelle Dziejman. 2011. "Identification of Vibrio cholerae Type III Secretion System Effector Proteins." Infection and Immunity 79, no. 4: 1728-1740.
Members of the heterotrophic bacterial family Vibrionaceae are native inhabitants of aquatic environments worldwide, constituting a diverse and abundant component of marine microbial organisms. Over 60 species of the genus Vibrio have been identified (Thompson et al., 2004) and their phenotypic heterogeneity is well documented. The ecology of the genus remains less well understood, however, despite reports that vibrios are the dominant microorganisms inhabiting the superficial water layer and colonizing the chitinous exoskeleton of zooplankton (e.g., copepods, Thompson et al., 2004). Although some species were originally isolated from seawater as free living organisms, most were isolated in association with marine life such as bivalves, fish, eels, or shrimp.
Michelle Dziejman; Fitnat H. Yildiz. Genomics of Pathogenic Vibrio Species. Genomics of Foodborne Bacterial Pathogens 2010, 267 -310.
AMA StyleMichelle Dziejman, Fitnat H. Yildiz. Genomics of Pathogenic Vibrio Species. Genomics of Foodborne Bacterial Pathogens. 2010; ():267-310.
Chicago/Turabian StyleMichelle Dziejman; Fitnat H. Yildiz. 2010. "Genomics of Pathogenic Vibrio Species." Genomics of Foodborne Bacterial Pathogens , no. : 267-310.
Strain AM-19226 is a pathogenic non-O1/non-O139 serogroup Vibrio cholerae strain that does not encode the toxin-coregulated pilus or cholera toxin but instead causes disease using a type three secretion system (T3SS). Two genes within the T3SS pathogenicity island, herein named vttR A (locus tag A33_1664) and vttR B (locus tag A33_1675), are predicted to encode proteins that show similarity to the transcriptional regulator ToxR, which is found in all strains of V. cholerae . Strains with a deletion of vttR A or vttR B showed attenuated colonization in vivo , indicating that the T3SS-encoded regulatory proteins play a role in virulence. lacZ transcriptional reporter fusions to intergenic regions upstream of genes encoding the T3SS structural components identified growth in the presence of bile as a condition that modulates gene expression. Under this condition, VttR A and VttR B were necessary for maximal gene expression. In contrast, growth in bile did not substantially alter the expression of a reporter fusion to the vopF gene, which encodes an effector protein. Increased vttR B reporter fusion activity was observed in a Δ vttR B strain background, suggesting that VttR B may regulate its own expression. The collective results are consistent with the hypothesis that T3SS-encoded regulatory proteins are essential for pathogenesis and control the expression of selected T3SS genes.
Ashfaqul Alam; Vincent Tam; Elaine Hamilton; Michelle Dziejman. vttR A and vttR B Encode ToxR Family Proteins That Mediate Bile-Induced Expression of Type Three Secretion System Genes in a Non-O1/Non-O139 Vibrio cholerae Strain. Infection and Immunity 2010, 78, 2554 -2570.
AMA StyleAshfaqul Alam, Vincent Tam, Elaine Hamilton, Michelle Dziejman. vttR A and vttR B Encode ToxR Family Proteins That Mediate Bile-Induced Expression of Type Three Secretion System Genes in a Non-O1/Non-O139 Vibrio cholerae Strain. Infection and Immunity. 2010; 78 (6):2554-2570.
Chicago/Turabian StyleAshfaqul Alam; Vincent Tam; Elaine Hamilton; Michelle Dziejman. 2010. "vttR A and vttR B Encode ToxR Family Proteins That Mediate Bile-Induced Expression of Type Three Secretion System Genes in a Non-O1/Non-O139 Vibrio cholerae Strain." Infection and Immunity 78, no. 6: 2554-2570.