Host stimuli and operator binding sites controlling protein interactions between virulence master regulator ToxR and ToxS in Vibrio cholerae.

Protein-protein interactions (PPIs) are key mechanisms in the maintenance of biological regulatory networks. Herein, we characterize PPIs within ToxR and its co-activator, ToxS, to understand the mechanisms of ToxR transcription factor activation. ToxR is a key transcription activator that is supported by ToxS for virulence gene regulation in Vibrio cholerae.

Regulated Proteolysis in Allowing Rapid Adaptation to Stress Conditions.

The lifecycle of the causative agent of the severe secretory diarrheal disease cholera, , is characterized by the transition between two dissimilar habitats, i.e., as a natural inhabitant of aquatic ecosystems and as a pathogen in the human gastrointestinal tract.

Proteolysis of ToxR is controlled by cysteine-thiol redox state and bile salts in Vibrio cholerae.

In Vibrio cholerae, virulence gene expression is regulated by a transmembrane-localized transcription factor complex designated as ToxRS. ToxR harbours two cysteines in the periplasmic domain that can form inter- and intramolecular disulfide bonds. In this study, we investigated the σ -dependent inner membrane proteolysis of ToxR, which occurs via the periplasmic-localized proteases DegS and DegP.