Quorum sensing regulates the transcription of lateral flagellar genes in Vibrio parahaemolyticus

: Aim: Investigation of the lateral flagellar (Laf) genes transcription by the quorum sensing (QS) regulators AphA and OpaR in Vibrio parahaemolyticus. Materials & methods: Regulation mechanisms were assessed by combined utilization of swarming motility assay, qPCR, LacZ fusion, EMSA and DNase I footprinting. Results: AphA and OpaR oppositely regulate swarming motility and Laf genes. At high cell density, OpaR bound to the regulatory regions of motY-lafK-fliEFGHIJ, fliMNPQR-flhBA, fliDSTKLA-motAB and lafA to repress their transcription. At low cell density, AphA indirectly activated their transcription. Conclusion: OpaR repression of swarming motility was via its direct repression of Laf genes, while AphA exerted its regulatory effect on swarming motility through unknown regulator(s).