Project description:Vibrio cholerae is a Gram negative, motile, facultative anaerobic bacterium, and the causative agent of cholera, a severe diarrhoeal disease, which untreated can rapidly lead to dehydration, hypotensive shock, and death. Cholera is a significant human disease that is estimated to affect 3-5 million people each year. The mechanism by which V. cholerae regulates virulence gene expression in vivo is unknown, but a number of studies have suggested that low molecular weight signally molecules may be important in modulating gene expression. cFP is a low molecular weight cyclic dipeptide produced by multiple Vibrio species. Evidence previously generated in our laboratory showed that cFP inhibited the production of the virulence factors cholera toxin (CT) and the toxin coregulated pilus (TCP) in O1 El Tor V. cholerae strain N16961 during growth under virulence gene inducing conditions. cFP inhibition of CT and TCP production correlated with reduced transcription of several regulators that belong to the ToxR regulon. To identify additional cFP-responsive genes we performed microarray experiments with the O1 El Tor V. cholerae strain N16961. In these experiments N16961 was grown under virulence gene inducing conditions in the presence and absence of cFP before RNA was extracted and hybridized to microarrays. The results showed that cFP positively affected the expression of the LysR-family regulatory protein LeuO. This finding suggests the possibility that LeuO may be mediating cFP-dependent regulation of gene expression in response to environmental cFP.
Project description:The transcriptional factor ToxR initiates a virulence regulatory cascade required for V. cholerae to express critical 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 encoding the majority of 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 that also define the major transitions of V. cholerae pandemic lineages. We demonstrate that ToxR shares nearly half 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 H-NS abrogates the need of 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, like H-NS, factors in addition to linear DNA sequence drive selection of ToxR binding sites.
Project description:The transcriptional factor ToxR initiates a virulence regulatory cascade required for V. cholerae to express critical 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 encoding the majority of 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 that also define the major transitions of V. cholerae pandemic lineages. We demonstrate that ToxR shares nearly half 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 H-NS abrogates the need of 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, like H-NS, factors in addition to linear DNA sequence drive selection of ToxR binding sites.
Project description:The transcriptional factor ToxR initiates a virulence regulatory cascade required for V. cholerae to express critical 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 encoding the majority of 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 that also define the major transitions of V. cholerae pandemic lineages. We demonstrate that ToxR shares nearly half 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 H-NS abrogates the need of 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, like H-NS, factors in addition to linear DNA sequence drive selection of ToxR binding sites.
Project description:Vibrio cholerae is a Gram negative, motile, facultative anaerobic bacterium, and the causative agent of cholera, a severe diarrhoeal disease, which untreated can rapidly lead to dehydration, hypotensive shock, and death. Cholera is a significant human disease that is estimated to affect 3-5 million people each year. The mechanism by which V. cholerae regulates virulence gene expression in vivo is unknown, but a number of studies have suggested that low molecular weight signally molecules may be important in modulating gene expression. cFP is a low molecular weight cyclic dipeptide produced by multiple Vibrio species. Evidence previously generated in our laboratory showed that cFP inhibited the production of the virulence factors cholera toxin (CT) and the toxin coregulated pilus (TCP) in O1 El Tor V. cholerae strain N16961 during growth under virulence gene inducing conditions. cFP inhibition of CT and TCP production correlated with reduced transcription of several regulators that belong to the ToxR regulon. To identify additional cFP-responsive genes we performed microarray experiments with the O1 El Tor V. cholerae strain N16961. In these experiments N16961 was grown under virulence gene inducing conditions in the presence and absence of cFP before RNA was extracted and hybridized to microarrays. The results showed that cFP positively affected the expression of the LysR-family regulatory protein LeuO. This finding suggests the possibility that LeuO may be mediating cFP-dependent regulation of gene expression in response to environmental cFP. V. cholerae N16961 was grown under AKI growth condition in the presence or absence of 1 mM cFP for 2.5 or 3 hours when total RNA was extracted, differentially labelled and hybridized to microarrays. Four independent experiments were performed.
Project description:In this study, we determined the TfoY regulon of V. cholerae using RNA-seq to better uderstand the protein's function. mRNA profiles of a WT V. cholerae O1 El Tor strain (A1552) and of a TfoY-producing derivative of the WT strain (A1552-TntfoY). 3 independent biological replicates are provided for each bacterial strain. The bacteria were grown to high cell density and in the presence of arabinose (to induce TfoY in strain A1552-TntfoY).
Project description:The transcriptional factor ToxR initiates a virulence regulatory cascade required for V. cholerae to express critical 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 ToxRâs genome-wide DNA-binding profile and show that ToxR is a global regulator of both progenitor genome-encoded genes and horizontally acquired islands encoding the majority of V. choleraeâs major virulence factors. Our results suggest that ToxR has gained regulatory control over important acquired elements that not only drive V. cholerae pathogenesis but that also define the major transitions of V. cholerae pandemic lineages. We demonstrate that ToxR shares nearly half 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 H-NS abrogates the need of 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, like H-NS, factors in addition to linear DNA sequence drive selection of ToxR binding sites. We used ChIP-seq to identify ToxR binding sites across the genome to determine the direct regulon of ToxR