A new class of inhibitors of the AraC family virulence regulator Vibrio cholerae ToxT

Anne K Woodbrey,Evans O Onyango,F Jon Kull,Maria Pellegrini,Ronald K Taylor,Gordon W Gribble,Gabriela Kovacikova

doi:10.1038/srep45011

Abstract

Vibrio cholerae is responsible for the diarrheal disease cholera that infects millions of people worldwide. While vaccines protecting against cholera exist, and oral rehydration therapy is an effective treatment method, the disease will remain a global health threat until long-term solutions such as improved sanitation and access to clean water become widely available. Because of this, there is a pressing need for potent therapeutics that can either mitigate cholera symptoms, or act prophylactically to prevent the virulent effects of a cholera infection. Here we report the design, synthesis, and characterization of a set of compounds that bind and inhibit ToxT, the transcription factor that directly regulates the two primary V. cholerae virulence factors. Using the folded structure of the monounsaturated fatty acid observed in the X-ray structure of ToxT as a template, we designed ten novel compounds that inhibit the virulence cascade to a greater degree than any known inhibitor. Our findings provide a structural and functional basis for the development of viable antivirulence therapeutics that combat cholera and, potentially, other forms of bacterial pathogenic disease.

Highlights

Enteric diarrheal disease continues to be a global health concern and is especially deadly to children in third world countries[1,2]
We present evidence that our most potent small-molecule inhibitors inhibit expression of essential colonization genes at 50 nM concentrations. These compounds represent a set of potential drug therapeutics that we show to be the most effective inhibitors of ToxT-regulated virulence gene expression described to date
The search for a strategy to combat Vibrio cholerae infections has been an ongoing focus of research in the field

Summary

Introduction

Enteric diarrheal disease continues to be a global health concern and is especially deadly to children in third world countries[1,2]. While many enteric bacteria are acid labile, pathogens that survive conditions in the stomach[3,4,5,6] go on to produce virulence factors through a chain of transcriptional events initiated by environmental stimuli. The inhibitory effects of bile on V. cholerae virulence were eventually attributed to its unsaturated fatty acid (UFA) components[19] While these findings documented inhibition of ToxT-activated gene expression by UFAs, a direct link between ToxT and fatty acids was not revealed until the X-ray structure was solved[20]. We present evidence that our most potent small-molecule inhibitors inhibit expression of essential colonization genes at 50 nM concentrations These compounds represent a set of potential drug therapeutics that we show to be the most effective inhibitors of ToxT-regulated virulence gene expression described to date

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Results

Conclusion