Quorum sensing and QsvR tightly control the transcription of encoding an active RNase II-type protein in .

Vibrio parahaemolyticus, a Gram-negative, halophilic bacterium, is a leading cause of acute gastroenteritis in humans. AphA and OpaR are the master quorum sensing (QS) regulators operating at low cell density (LCD) and high cell density (HCD), respectively. QsvR is an AraC-type protein that integrates into the QS system to control gene expression by directly controlling the transcription of and . However, the regulation of QsvR itself remains unclear to date. In this study, we show that and are transcribed as an operon, -. AphA indirectly activates the transcription of at LCD, whereas OpaR and QsvR directly repress transcription at HCD, leading to the highest expression levels of occurs at LCD. Moreover, VPA0607 acts as an active RNase II-type protein in and feedback inhibits the expression of QsvR at the post-transcriptional level. Taken together, this work deepens our understanding of the regulation of QsvR and enriches the integration mechanisms of QsvR with the QS system in .