Expression of VjbR under Nutrient Limitation Conditions Is Regulated at the Post-Transcriptional Level by Specific Acidic pH Values and Urocanic Acid

摘要: VjbR is a LuxR homolog that regulates transcription of many genes including important virulence determinants the facultative intracellular pathogen Brucella abortus. This factor belongs to family regulators participate in cell-cell communication process called quorum sensing, which enables bacteria respond changes cell population density by monitoring concentration self produced autoinducer molecules. Unlike almost all other LuxR-type proteins, binds DNA and activates absence any signal. To investigate mechanisms induces VjbR-mediated transcriptional activation, determine how inappropriate spatio-temporal expression target prevented, we focused on study vjbR itself. By assaying different parameters related lifestyle Brucella, identified restricted set conditions triggers protein expression. Such required convergence two signals nature: specific pH value 5.5 presence urocanic acid, metabolite involved connection between metabolism Brucella. In addition, also observed an pH-dependent RibH2 VirB7, additional survival-related proteins Analysis promoter activities determination mRNA levels demonstrated acid-dependent induced VjbR, RibH2, VirB7 act at post-transcriptional level. Taken together, our findings support model whereby modulating response changing environment encountered within host.