Quorum sensing signal synthases enhance Vibrio parahaemolyticus swarming motility

Abstract

AbstractVibrio parahaemolyticus is a significant food‐borne pathogen that is found in diverse aquatic habitats. Quorum sensing (QS), a signaling system for cell–cell communication, plays an important role in V. parahaemolyticus persistence. We characterized the function of three V. parahaemolyticus QS signal synthases, CqsAvp, LuxMvp, and LuxSvp, and show that they are essential to activate QS and regulate swarming. We found that CqsAvp, LuxMvp, and LuxSvp activate a QS bioluminescence reporter through OpaR. However, V. parahaemolyticus exhibits swarming defects in the absence of CqsAvp, LuxMvp, and LuxSvp, but not OpaR. The swarming defect of this synthase mutant (termed Δ3AI) was recovered by overexpressing either LuxOvpD47A, a mimic of dephosphorylated LuxOvp mutant, or the scrABC operon. CqsAvp, LuxMvp, and LuxSvp inhibit lateral flagellar (laf) gene expression by inhibiting the phosphorylation of LuxOvp and the expression of scrABC. Phosphorylated LuxOvp enhances laf gene expression in a mechanism that involves modulating c‐di‐GMP levels. However, enhancing swarming requires phosphorylated and dephosphorylated LuxOvp which is regulated by the QS signals that are synthesized by CqsAvp, LuxMvp, and LuxSvp. The data presented here suggest an important strategy of swarming regulation by the integration of QS and c‐di‐GMP signaling pathways in V. parahaemolyticus.