Coordinated regulation of various acid survival systems in response to environmental stimuli is crucial for the adaptation of enteropathogenic bacteria to acidic environments such as the stomach. In this study, we demonstrated that the RovM protein, a central regulator of the CsrABC-RovM-RovA cascade, conversely regulates the expression of two acid survival systems in Yersinia pseudotuberculosis by acting as a dual transcriptional regulator. RovM activated the expression of T6SS4, which is essential for bacterial survival under mild acidic conditions, by binding upstream of the T6SS4 promoter. On the contrary, RovM repressed the expression of a functional arginine-dependent acid resistance system (AR3), which is crucial for bacterial survival under strong acidic conditions, by directly binding to the -35 element in the AR3 promoter. Consistent with previous findings that rovM expression responds to the availability of nutrients, the expression of T6SS4 and AR3 was differentially regulated by nutritional status. Based on these results, a dynamic model whereby RovM coordinately regulates the expression of AR3 and T6SS4 in response to the availability of nutrients in the environment was proposed.
© 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.