Virstatin inhibits dimerization of the transcriptional activator ToxT

Shakhnovich, Elizabeth A.; Hung, Deborah T.; Pierson, Emily; Lee, Kyung-Ae; Mekalanos, John J.

doi:10.1073/pnas.0611643104

Cited by 117 publications

(135 citation statements)

References 26 publications

(29 reference statements)

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“…The type 2 interaction is very spacing sensitive, as a difference of even 1 bp from the wild-type spacing abrogates transcription activation at some promoters. However, the acfA and aldA promoters were the promoters least sensitive to virstatin treatment (37), suggesting that the type 2 interaction is virstatin insensitive. A type 3 interaction occurs between ␣-CTD and ToxT at a distal toxbox oriented so that it "points away" from the promoter.…”

Section: Discussionmentioning

confidence: 96%

“…Furthermore, insertion of 5 or 10 bp between the promoter-proximal toxbox and the Ϫ35 box at the tcpA promoter also abrogated transcription activation by ToxT (unpublished data), suggesting that the spacing of the toxboxes relative to the promoter is important for activation. There is evidence from domain swapping experiments that ToxT Nterminal domains can associate with each other to form dimers or multimers (33,37), but full-length ToxT was not observed to dimerize in such an assay (37). It is possible that ToxT monomers associate with each other at some promoters and that this association is important for transcription activation.…”

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confidence: 99%

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Flexibility of Vibrio cholerae ToxT in Transcription Activation of Genes Having Altered Promoter Spacing

Bellair

Withey

2008

J Bacteriol

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Cholera, a severe diarrheal disease, is caused by ingestion of the gram-negative bacterium Vibrio cholerae. Expression of V. cholerae virulence factors is highly regulated at the transcriptional and posttranscriptional levels by a complex network of proteins and small noncoding RNAs. The direct activator of transcription of most V. cholerae virulence genes is the ToxT protein. ToxT binds to a 13-bp sequence, the toxbox, located upstream of genes in its regulon. However, the organization of toxboxes relative to each other and to the core promoter elements at different genes varies dramatically. At different ToxT-activated genes a single toxbox may be necessary and sufficient for full activation, or pairs of toxboxes organized as either inverted or direct repeats may be required for full activation. Although all toxboxes are located at positions consistent with a class I promoter architecture, the locations of toxboxes relative to the transcription start site also vary from gene to gene. To further assess the ability of ToxT to activate transcription from different configurations relative to the core promoter elements, we constructed promoter-lacZ fusions having altered spacing both between toxbox pairs and between the promoter-proximal toxbox and the ؊35 box at five different ToxT-activated promoters. Our results suggest that that ToxT has remarkable flexibility in its positioning as a transcription activator and that different interactions between ToxT and RNA polymerase occur during transcription activation of promoters having different toxbox configurations.The gram-negative bacterium Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, continues to be a serious public health problem despite over 100 years of research on its pathogenesis. The current cholera pandemic, which began in 1961, continues unabated, and an estimated 5 million cases of cholera occur worldwide each year. Although over 200 known serogroups of V. cholerae have been identified, only the O1 and O139 serogroups are capable of causing pandemic cholera (34,35).Pandemic V. cholerae strains require two major virulence factors for colonization and pathogenesis. The first factor, cholera toxin, is an A 1 B 5 -type ADP-ribosylating toxin that is responsible for producing the voluminous watery diarrhea characteristic of cholera (8,26). The genes encoding cholera toxin, ctxAB, are carried in the genome of a lysogenic bacteriophage, CTX⌽ (40). The second major virulence factor is the toxin-coregulated pilus (TCP) (38), a type IV pilus that initiates microcolony formation and is required for intestinal colonization by V. cholerae (39). Genes encoding the TCP, which are in a long operon beginning with the tcpA pilin gene, are located in the Vibrio pathogenicity island (VPI) (22). In addition to its role as a colonization factor, the TCP is also the receptor for CTX⌽ and thus allows horizontal transfer of ctxAB to nontoxigenic V. cholerae carrying the VPI (40). In addition to the TCP-encoding genes, several other genes thought to...

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Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

Flexibility of Vibrio cholerae ToxT in Transcription Activation of Genes Having Altered Promoter Spacing

Bellair

Withey

2008

J Bacteriol

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“…Consequently, development of anti-virulence drugs is proceeding (Waldor, 2006). An example is the small molecule inhibitor of V. cholerae intestinal colonization, virstatin [N-(1, 8-(naphthalimide)-n-butyric acid], which was identified in a high-throughput phenotypic screen (Hung et al, 2005;Shakhnovich et al, 2007Shakhnovich et al, , 2007a. This molecule inhibits ctxAB and tcpA transcription by preventing dimerization of their positive regulator, ToxT (Shakhnovich et al, 2007a).…”

Section: Significance To Anti-virulence Drug Discoverymentioning

confidence: 99%

“…An example is the small molecule inhibitor of V. cholerae intestinal colonization, virstatin [N-(1, 8-(naphthalimide)-n-butyric acid], which was identified in a high-throughput phenotypic screen (Hung et al, 2005;Shakhnovich et al, 2007Shakhnovich et al, , 2007a. This molecule inhibits ctxAB and tcpA transcription by preventing dimerization of their positive regulator, ToxT (Shakhnovich et al, 2007a). Another example is the newly identified inhibitor of the Na + -dependent flagellar motor, Q24DA, which could prevent infection dissemination by blocking motility and indirectly diminishing CT and TCP secretion (Rasmussen et al, 2010.…”

Section: Significance To Anti-virulence Drug Discoverymentioning

confidence: 99%

Integration of Global Regulatory Mechanisms Controlling Vibrio Cholerae Behavior

Benítez¹,

Silva²

2012

Cholera

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“…To examine whether dimerization played a role in the transcriptional regulation of msh genes by ToxT, we examined the effects of a known inhibitor of ToxT dimerization, virstatin (14,24), on the transcription of msh genes in E. coli (Fig. 1A).…”

Section: Identification Of Toxt Regulatory Sites At the Msh Locusmentioning

confidence: 99%

Direct Regulation by theVibrio choleraeRegulator ToxT To Modulate Colonization and Anticolonization Pilus Expression

Hsiao

Kan

et al. 2009

Infect Immun

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The pathogen Vibrio cholerae uses a large number of coordinated transcriptional regulatory events to transition from its environmental reservoir to the host and establish itself at its preferred colonization site at the host intestinal mucosa. The key regulator in this process is the AraC/XylS family transcription factor, ToxT, which plays critical roles in pathogenesis, including the regulation of two type IV pili, the anticolonization factor mannose-sensitive hemagglutinin and the toxin-coregulated pilus. Previously, it was thought ToxT required dimerization in order to effect transcriptional regulation at its cognate promoters. Here, we present evidence that ToxT directly represses transcription of the msh operon by binding to three promoters within this operon and that dimerization may not be required for transcriptional repression of target promoters by ToxT, suggesting that this regulator uses different mechanisms to modulate the transcriptional repertoire of V. cholerae.Vibrio cholerae is a gram-negative bacterium normally found in aquatic reservoirs. It is also the etiologic agent of cholera, a severe dehydrating diarrhea that affects hundreds of thousands of people each year. Cholera is characterized by voluminous diarrhea caused by the action of the cholera toxin (CT), produced by vibrios colonizing the mucosa of the small intestine. The transitions between the stages of the infectious cycle of this pathogen, between colonization, toxin production, and dissemination back into the aquatic reservoir, is governed by a transcriptional cascade that regulates the production of virulence factors such as CT and the biogenesis of the colonization determinant the toxin-coregulated pilus (TCP). In addition to these provirulence factors, some elements, including the mannose-sensitive hemagglutinin (MSHA) pilus and quorum-sensing systems, which as "anticolonization factors" can have a negative influence on pathogenesis, are downregulated during infection (12,16).The keystone of the transcriptional regulatory system that governs the phenotypic shifts in this transition from aquatic organism to human pathogen is the AraC/XylS family transcription factor ToxT, which is the major regulator of pathogenesis activated in response to entry into the intestine (5, 11). At the end of this cascade are the biogenesis systems for two related but functionally antagonistic type IV pili, the TCP, and MSHA pili. The tight regulation of pili biogenesis is critical for V. cholerae infection, as TCP is necessary for colonization of the host intestinal mucosa (10, 26). The presence of MSHA pili, on the other hand, is actively detrimental to survival in the host, since it binds secretory immunoglobulin A antibodies that, synergistically with the mucin glycocalyx of the intestinal mucosa (17), excludes pathogens such as V. cholerae from the epithelium. We have previously demonstrated that ToxT plays an important part in V. cholerae fitness in infection by resolving the conflicting pressures of these two type IV pili functions by downregul...

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Virstatin inhibits dimerization of the transcriptional activator ToxT

Cited by 117 publications

References 26 publications

Flexibility of Vibrio cholerae ToxT in Transcription Activation of Genes Having Altered Promoter Spacing

Flexibility of Vibrio cholerae ToxT in Transcription Activation of Genes Having Altered Promoter Spacing

Integration of Global Regulatory Mechanisms Controlling Vibrio Cholerae Behavior

Direct Regulation by theVibrio choleraeRegulator ToxT To Modulate Colonization and Anticolonization Pilus Expression

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