Related Experiment Video
Updated: Jun 17, 2026

Laboratory Techniques Used to Maintain and Differentiate Biotypes of Vibrio cholerae Clinical and Environmental Isolates
Published on: May 30, 2017
Virulence regulator AphB enhances toxR transcription in Vibrio cholerae
Xiao Xu1, Andrew M Stern, Zhi Liu
1State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Beijing, PR China. allenxu426@hotmail.com
Background:
Vibrio cholerae is the causative agent of cholera. Extensive studies reveal that complicated regulatory cascades regulate expression of virulence genes, the products of which are required for V. cholerae to colonize and cause disease. In this study, we investigated the expression of the key virulence regulator ToxR under different conditions.
Results:
We found that compared to that of wild type grown to stationary phase, the toxR expression was lower in an aphB mutant strain. AphB has been previously shown to be a key virulence regulator that is required to activate the expression of tcpP. When expressed constitutively, AphB is able to activate the toxR promoter. Furthermore, gel shift analysis indicates that AphB binds toxR promoter region directly. We also characterize the effect of AphB on the levels of the outer membrane porins OmpT and OmpU, which are known to be regulated by ToxR.
Conclusions:
Our data indicate that V. cholerae possesses an additional regulatory loop that use AphB to activate the expression of two virulence regulators, ToxR and TcpP, which together control the expression of the master virulence regulator ToxT.
Related Concept Videos
Regulation of Bacterial Virulence
Cholera
Bacterial Toxins
Determinants of Bacterial Pathogenicity and Virulence
Other Stress Responses in Bacteria
Stringent Response in E. coli

