Modulation of CrbS-Dependent Activation of the Acetate Switch in Vibrio cholerae.

controls the pathogenicity of interactions with arthropod hosts via the activity of the CrbS/R two-component system. This signaling pathway regulates the consumption of acetate, which in turn alters the relative virulence of interactions with arthropods, including CrbS is a histidine kinase that links a transporter-like domain to its signaling apparatus via putative STAC and PAS domains. CrbS and its cognate response regulator are required for the expression of acetyl coenzyme A (acetyl-CoA) synthetase (product of ), which converts acetate to acetyl-CoA. We demonstrate that the STAC domain of CrbS is required for signaling in culture; without it, transcription is reduced in LB medium, and cannot grow on acetate minimal media. However, the strain remains virulent toward and expresses similarly to the wild type during infection. This suggests that there is a unique signal or environmental variable that modulates CrbS in the gastrointestinal tract of Second, we present evidence in support of CrbR, the response regulator that interacts with CrbS, binding directly to the promoter, and we identify a region of the promoter that CrbR may target. We further demonstrate that nutrient signals, together with the cAMP receptor protein (CRP)-cAMP system, control transcription, but regulation may occur indirectly, as CRP-cAMP activates the expression of the and genes. Finally, we define the role of the Pta-AckA system in and identify redundancy built into acetate excretion pathways in this pathogen. CrbS is a member of a unique family of sensor histidine kinases, as its structure suggests that it may link signaling to the transport of a molecule. However, mechanisms through which CrbS senses and communicates information about the outside world are unknown. In the , orthologs of CrbS regulate acetate metabolism, which can, in turn, affect interactions with host organisms. Here, we situate CrbS within a larger regulatory framework, demonstrating that is regulated by nutrient-sensing systems. Furthermore, CrbS domains may play various roles in signaling during infection and growth in culture, suggesting a unique mechanism of host recognition. Finally, we define the roles of additional pathways in acetate flux, as a foundation for further studies of this metabolic nexus point.