scholarly journals ToxR-Independent Expression of Cholera Toxin from the Replicative Form of CTXφ

1998 ◽  
Vol 66 (1) ◽  
pp. 394-397 ◽  
Author(s):  
Sara Lazar ◽  
Matthew K. Waldor
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Toxin Production ◽  
Recipient Strain ◽  
Replicative Form ◽  
Filamentous Bacteriophage ◽  
Infant Mouse ◽  
Mouse Intestine

ABSTRACT The ctxAB operon, which encodes cholera toxin, resides in the genome of CTXφ, a filamentous bacteriophage. WithinVibrio cholerae cells, the CTXφ genome can exist either as a replicating plasmid or as a prophage integrated into the chromosome. Previous work established that ToxR is required for chromosomal ctxAB expression. We have learned that strains harboring the CTXφ replicative form produce cholera toxin under all conditions tested, independently of ToxR. During passage of CTXφ lysogens through the infant mouse intestine, transduction of CTXφ to a recipient strain can be detected, indicating that phage excision and replication occur in vivo. These results suggest that phage induction might provide a novel mechanism for the regulation of cholera toxin production.

scholarly journals Characterization of Ferric and Ferrous Iron Transport Systems in Vibrio cholerae

2006 ◽  
Vol 188 (18) ◽  
pp. 6515-6523 ◽  
Author(s):  
Elizabeth E. Wyckoff ◽  
Alexandra R. Mey ◽  
Andreas Leimbach ◽  
Carolyn F. Fisher ◽  
Shelley M. Payne
Keyword(s):  
Vibrio Cholerae ◽  
Transport System ◽  
Iron Transport ◽  
Iron Acquisition ◽  
Shigella Flexneri ◽  
Transport Systems ◽  
Infant Mouse ◽  
Mouse Intestine ◽  
Dependent Transport

ABSTRACT Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.

scholarly journals Activation of the Vibrio cholerae SOS Response Is Not Required for Intestinal Cholera Toxin Production or Colonization

2006 ◽  
Vol 74 (2) ◽  
pp. 927-930 ◽  
Author(s):  
Mariam Quinones ◽  
Brigid M. Davis ◽  
Matthew K. Waldor
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Sos Response ◽  
Toxin Production ◽  
Mrna Levels ◽  
Suckling Mouse ◽  
Potent Inducer ◽  
Genes Encoding ◽  
Mouse Intestine ◽  
Ctx Prophage

ABSTRACT Cholera toxin, one of the main virulence factors of Vibrio cholerae, is encoded in the genome of CTXφ, a V. cholerae-specific lysogenic filamentous bacteriophage. Although the genes encoding cholera toxin, ctxAB, are known to have their own promoter, the toxin genes can also be transcribed from an upstream CTXφ promoter, PrstA . The V. cholerae SOS response to DNA damage induces the CTX prophage by stimulating gene expression initiating from PrstA . Here, we investigated whether ctxA mRNA levels increase along with the levels of the transcripts for the other CTXφ genes following stimulation of the V. cholerae SOS response. Treatment of V. cholerae with the SOS-inducing agent mitomycin C increased the level of ctxA mRNA approximately sevenfold, apparently by augmenting the activity of PrstA . However, using suckling mice as a model host, we found that intraintestinal ctxA transcription does not depend on PrstA . In fact, the suckling mouse intestine does not appear to be a potent inducer of the V. cholerae SOS response. Furthermore, alleviation of LexA-mediated repression of the V. cholerae SOS regulon was not required for V. cholerae growth in the suckling mouse intestine. Our observations suggest that pathogenicity of V. cholerae does not depend on its SOS response.

scholarly journals In vitro and in vivo cholera toxin production by classical and El Tor isolates of Vibrio cholerae.

1985 ◽  
Vol 21 (6) ◽  
pp. 884-890 ◽  
Author(s):  
P C Turnbull ◽  
J V Lee ◽  
M D Miliotis ◽  
C S Still ◽  
M Isaäcson ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Toxin Production ◽  
El Tor

Induction of the Lysogenic Phage Encoding Cholera Toxin in Naturally Occurring Strains of Toxigenic Vibrio cholerae O1 and O139

1998 ◽  
Vol 66 (8) ◽  
pp. 3752-3757 ◽  
Author(s):  
Shah M. Faruque ◽  
Asadulghani ◽  
A. R. M. Abdul Alim ◽  
M. John Albert ◽  
K. M. Nasirul Islam ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Natural Habitat ◽  
Recipient Strain ◽  
Dna Probe ◽  
Naturally Occurring ◽  
Vibrio Cholerae O1 ◽  
Probe Assay ◽  
Culture Positive

ABSTRACT In toxigenic Vibrio cholerae, the CTX genetic element which carries the genes for cholera toxin (CT) is the genome of a lysogenic bacteriophage (CTXΦ). Clinical and environmental strains ofV. cholerae O1 or O139 and stools that were culture positive for cholera were analyzed to study the induction and transmission of CTXΦ. To our knowledge, this is the first report of the examination of CTXΦ in clinical materials and in naturally occurring strains. DNA probe analysis revealed that 4.25% (6 of 141) of the isolated V. cholerae strains spontaneously produced a detectable level of extracellular CTXΦ particles in the culture supernatants whereas another 34.04% (48 of 141) produced CTXΦ particles when induced with mitomycin C. CTXΦ isolated from 10 clinical or environmental strains infected a CT-negative recipient strain, CVD103, both inside the intestines of infant mice and under laboratory conditions. All culture-positive stools analyzed were negative for the presence of CTXΦ both in the DNA probe assay and by in vivo assay for the infection of the recipient strain in infant mice. These results suggested that naturally occurring strains of toxigenicV. cholerae are inducible lysogens of CTXΦ but that cholera pathogenesis in humans is not associated with the excretion of CTXΦ particles in stools, indicating that induction of the phage may not occur efficiently inside the human intestine. However, in view of the efficient transmission of the phage under conditions conducive to the expression of toxin-coregulated pili, it appears that propagation of CTXΦ in the natural habitat may involve both environmental and host factors.

scholarly journals MetR-Regulated Vibrio cholerae Metabolism Is Required for Virulence

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Ryan W. Bogard ◽  
Bryan W. Davies ◽  
John J. Mekalanos
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Virulence Factor ◽  
Current Knowledge ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Content Type ◽  
Mouse Intestine

ABSTRACTLysR-type transcriptional regulators (LTTRs) are the largest, most diverse family of prokaryotic transcription factors, with regulatory roles spanning metabolism, cell growth and division, and pathogenesis. Using a sequence-defined transposon mutant library, we screened a panel ofV. choleraeEl Tor mutants to identify LTTRs required for host intestinal colonization. Surprisingly, out of 38 LTTRs, only one severely affected intestinal colonization in the suckling mouse model of cholera: the methionine metabolism regulator, MetR. Genetic analysis of genes influenced by MetR revealed thatglyA1andmetJwere also required for intestinal colonization. Chromatin immunoprecipitation of MetR and quantitative reverse transcription-PCR (qRT-PCR) confirmed interaction with and regulation ofglyA1, indicating that misregulation ofglyA1is likely responsible for the colonization defect observed in themetRmutant. TheglyA1mutant was auxotrophic for glycine but exhibited wild-type trimethoprim sensitivity, making folate deficiency an unlikely cause of its colonization defect. MetJ regulatory mutants are not auxotrophic but are likely altered in the regulation of amino acid-biosynthetic pathways, including those for methionine, glycine, and serine, and this misregulation likely explains its colonization defect. However, mutants defective in methionine, serine, and cysteine biosynthesis exhibited wild-type virulence, suggesting that these amino acids can be scavenged in vivo. Taken together, our results suggest that glycine biosynthesis may be required to alleviate an in vivo nutritional restriction in the mouse intestine; however, additional roles for glycine may exist. Irrespective of the precise nature of this requirement, this study illustrates the importance of pathogen metabolism, and the regulation thereof, as a virulence factor.IMPORTANCEVibrio choleraecontinues to be a severe cause of morbidity and mortality in developing countries. Identification ofV. choleraefactors critical to disease progression offers the potential to develop or improve upon therapeutics and prevention strategies. To increase the efficiency of virulence factor discovery, we employed a regulator-centric approach to multiplex our in vivo screening capabilities and allow whole regulons inV. choleraeto be interrogated for pathogenic potential. We identified MetR as a new virulence regulator and serine hydroxymethyltransferase GlyA1 as a new MetR-regulated virulence factor, both required byV. choleraeto colonize the infant mouse intestine. Bacterial metabolism is a prerequisite to virulence, and current knowledge of in vivo metabolism of pathogens is limited. Here, we expand the known role of amino acid metabolism and regulation in virulence and offer new insights into the in vivo metabolic requirements ofV. choleraewithin the mouse intestine.

Cholera Toxin Production Induced upon Anaerobic Respiration is Suppressed by Glucose Fermentation in Vibrio cholerae

2016 ◽  
Vol 26 (3) ◽  
pp. 627-636 ◽  
Author(s):  
Young Taek Oh ◽  
Kang-Mu Lee ◽  
Wasimul Bari ◽  
Hwa Young Kim ◽  
Hye Jin Kim ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Anaerobic Respiration ◽  
Toxin Production ◽  
Glucose Fermentation

scholarly journals The El Tor Biotype of Vibrio cholerae Exhibits a Growth Advantage in the Stationary Phase in Mixed Cultures with the Classical Biotype

2009 ◽  
Vol 192 (4) ◽  
pp. 955-963 ◽  
Author(s):  
Subhra Pradhan ◽  
Amit K. Baidya ◽  
Amalendu Ghosh ◽  
Kalidas Paul ◽  
Rukhsana Chowdhury
Keyword(s):  
Amino Acids ◽  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Competitive Growth ◽  
Small Peptides ◽  
Ileal Loop ◽  
Infant Mouse ◽  
Culture Filtrates ◽  
El Tor

ABSTRACT Vibrio cholerae strains of the O1 serogroup that typically cause epidemic cholera can be classified into two biotypes, classical and El Tor. The El Tor biotype emerged in 1961 and subsequently displaced the classical biotype as a cause of cholera throughout the world. In this study we demonstrate that when strains of the El Tor and classical biotypes were cocultured in standard LB medium, the El Tor strains clearly had a competitive growth advantage over the classical biotype starting from the late stationary phase and could eventually take over the population. The classical biotype produces extracellular protease(s) in the stationary phase, and the amounts of amino acids and small peptides in the late stationary and death phase culture filtrates of the classical biotype were higher than those in the corresponding culture filtrates of the El Tor biotype. The El Tor biotype cells could utilize the amino acids more efficiently than the classical biotype under the alkaline pH of the stationary phase cultures but not in medium buffered to neutral pH. The growth advantage of the El Tor biotype was also observed in vivo using the ligated rabbit ileal loop and infant mouse animal models.

scholarly journals Spatiotemporal Analysis of Acid Adaptation-Mediated Vibrio cholerae Hyperinfectivity

2004 ◽  
Vol 72 (4) ◽  
pp. 2405-2407 ◽  
Author(s):  
Michael J. Angelichio ◽  
D. Scott Merrell ◽  
Andrew Camilli
Keyword(s):  
Small Intestine ◽  
Vibrio Cholerae ◽  
Spatiotemporal Analysis ◽  
Rapid Onset ◽  
Multiplication Rate ◽  
Acid Adaptation ◽  
Infant Mouse ◽  
Mouse Intestine ◽  
Kinetics Of ◽  
Transcriptional Induction

ABSTRACT Acid adaptation has previously been shown to increase the infectivity of Vibrio cholerae in the infant mouse model. To better understand this phenomenon, we monitored the spatial distribution and temporal changes in the ratios of acid-adapted cells to unadapted V. cholerae cells in the small intestine, as well as the timing of virulence factor expression. We found that the competitive advantage afforded by acid adaptation does not become manifest until greater than 3 h postinfection; thus, acid adaptation does not increase V. cholerae passage through the gastric acid barrier. Additionally, acid-adapted and unadapted V. cholerae cells colonize the same sections of the small intestine and show similar kinetics of transcriptional induction of the virulence genes tcpA and ctxA. These studies suggest that the increased infectivity of acid-adapted V. cholerae is due to a more rapid onset of multiplication and/or to an increased multiplication rate within the infant mouse intestine.

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