The membrane fusion protein (mfp) gene locus of Vibrio parahaemolyticus consists of two operons, cpsQ-mfpABC and mfpABC, which are both required for biofilm formation. ToxR and CalR are required for the full virulence of V. parahaemolyticus, and their mutual regulation has been demonstrated. Moreover, cell density-dependent expression of toxR was previously observed in V. parahaemolyticus, but details about the related mechanisms remained unclear. QsvR can work with the master quorum sensing (QS) regulators AphA and OpaR to regulate virulence expression and biofilm formation. In the present work, we showed that QsvR bound to the promoter-proximal DNA regions of toxR and calR to repress their transcription as well as occupying the regulatory regions of cpsQ-mfpABC and mfpABC to activate their transcription. Thus, we reconstructed the QsvR-dependent promoter organization of toxR, calR, cpsQ-mfpABC, and mfpABC. QsvR directly repressed toxR and calR transcription as well as directly activated cpsQ-mfpABC and mfpABC transcription. The data presented here promotes us to gain deeper knowledge of the regulatory network of the mfp locus in V. parahaemolyticus.

中文翻译：

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副溶血性弧菌毒力基因和生物膜形成相关操纵子的转录调控

副溶血性弧菌的膜融合蛋白（mfp）基因位点由两个操纵子cpsQ-mfpABC和mfpABC组成，这两个操纵子都是生物膜形成所必需的。ToxR和CalR是副溶血弧菌完全毒力所必需的，并且已经证明了它们的相互调节。此外，以前在副溶血性弧菌中观察到了细胞密度依赖性的toxR表达，但有关相关机制的细节仍不清楚。QsvR可以与主要群体感应（QS）调节器AphA和OpaR配合使用，以调节毒力表达和生物膜形成。在目前的工作中，我们表明QsvR绑定到toxR和calR的启动子近端DNA区，以抑制其转录，并占据cpsQ-mfpABC和mfpABC的调节区，以激活其转录。因此，我们重建了toxR，calR，cpsQ-mfpABC和mfpABC的QsvR依赖性启动子组织。QsvR直接抑制toxR和calR转录，以及直接激活cpsQ-mfpABC和mfpABC转录。此处提供的数据使我们获得了对溶血性弧菌mfp基因座调控网络的更深入的了解。