Dataset Information

The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.

ABSTRACT: ToxR of Vibrio cholerae directly activates the ompU promoter, but requires a second activator, TcpP to activate the toxT promoter. ompU encodes a porin, while toxT encodes the transcription factor, ToxT, which activates V. cholerae virulence genes including cholera toxin and the toxin co-regulated pilus. Using an ompU-sacB transcriptional fusion, toxR mutant alleles were identified that encode ToxR molecules defective for ompU promoter activation. Many toxR mutants defective for ompU activation affected residues involved in DNA binding. Mutants defective for ompU activation were also tested for activation of the toxT promoter. ToxR-F69A and ToxR-V71A, both in the ?-loop of ToxR, were preferentially defective for ompU activation, with ToxR-V71A nearly completely defective. Six mutants from the ompU-sacB selection showed more dramatic defects in toxT activation than ompU activation. All but one of the affected residues map to the wing domain of the winged helix-turn-helix of ToxR. Some ToxR mutants preferentially affecting toxT activation had partial DNA-binding defects, and one mutant, ToxR-P101L, had altered interactions with TcpP. These data suggest that while certain residues in the ?-loop of ToxR are utilized to activate the ompU promoter, the wing domain of ToxR contributes to both promoter binding and ToxR/TcpP interaction facilitating toxT activation.

SUBMITTER: Morgan SJ

PROVIDER: S-EPMC3124598 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.

Morgan Sarah J SJ Felek Suleyman S Gadwal Shilpa S Koropatkin Nicole M NM Perry Jeffrey W JW Bryson Alyson B AB Krukonis Eric S ES

Molecular microbiology 20110605 1

ToxR of Vibrio cholerae directly activates the ompU promoter, but requires a second activator, TcpP to activate the toxT promoter. ompU encodes a porin, while toxT encodes the transcription factor, ToxT, which activates V. cholerae virulence genes including cholera toxin and the toxin co-regulated pilus. Using an ompU-sacB transcriptional fusion, toxR mutant alleles were identified that encode ToxR molecules defective for ompU promoter activation. Many toxR mutants defective for ompU activation ...[more]

PMID: 21542860

Similar Datasets

Project description:UnlabelledVibrio cholerae, a Gram-negative bacterium, infects humans and causes cholera, a severe disease characterized by vomiting and diarrhea. These symptoms are primarily caused by cholera toxin (CT), whose production by V. cholerae is tightly regulated by the virulence cascade. In this study, we designed and carried out a high-throughput chemical genetic screen to identify inhibitors of the virulence cascade. We identified three compounds, which we named toxtazin A and toxtazin B and B', representing two novel classes of toxT transcription inhibitors. All three compounds reduce production of both CT and the toxin-coregulated pilus (TCP), an important colonization factor. We present evidence that toxtazin A works at the level of the toxT promoter and that toxtazins B and B' work at the level of the tcpP promoter. Treatment with toxtazin B results in a 100-fold reduction in colonization in an infant mouse model of infection, though toxtazin A did not reduce colonization at the concentrations tested. These results add to the growing body of literature indicating that small-molecule inhibitors of virulence genes could be developed to treat infections, as alternatives to antibiotics become increasingly needed.ImportanceV. cholerae caused more than 580,000 infections worldwide in 2011 alone (WHO, Wkly. Epidemiol. Rec. 87:289-304, 2012). Cholera is treated with an oral rehydration therapy consisting of water, glucose, and electrolytes. However, as V. cholerae is transmitted via contaminated water, treatment can be difficult for communities whose water source is contaminated. In this study, we address the need for new therapeutic approaches by targeting the production of the main virulence factor, cholera toxin (CT). The high-throughput screen presented here led to the identification of two novel classes of inhibitors of the virulence cascade in V. cholerae, toxtazin A and toxtazins B and B'. We demonstrate that (i) small-molecule inhibitors of virulence gene production can be identified in a high-throughput screen, (ii) targeting virulence gene production is an effective therapeutic strategy, and (iii) small-molecule inhibitors can uncover unknown layers of gene regulation, even in well-studied regulatory cascades.

Dataset Information

The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.

Publications

The two faces of ToxR: activator of ompU, co-regulator of toxT in Vibrio cholerae.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure