State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
Yantai Development Zone TianYuan Aquatic Products Co., Ltd., Yantai 264006, Shandong Province, China.
FEMS Microbiol Lett. 2019 Mar 1;366(6). doi: 10.1093/femsle/fnz056.
Quorum sensing (QS) system is an important bacterial cell-to-cell signaling system controlling expression of various genes in response to cell densities. In vibrios, LuxR/AphA are two established master QS regulators (MQSRs), and VqsA is recently identified to be the third putative MQSR. As a novel LysR-type regulator, the regulon and the underlying regulation mechanisms of VqsA remains to be elucidated. Here our investigation indicated that the yields of alkaline serine protease (Asp), the exotoxin in Vibrio alginolyticus was dependent on both LuxR and VqsA in growth phase dependent manner. Various in vivo and in vitro analyses including electrophoretic mobility shift assays (EMSA) along with DNase I footprinting investigations demonstrated that VqsA positively controls asp expression through directly binding to the partially palindromic 29 bp binding motif in the promoter region of asp. Moreover, RNA-seq analysis validated the regulatory roles of VqsA in various processes in the organism. Collectively, our data showed that VqsA positively regulates the expression of exotoxin and other virulence-associated genes and is essential for the QS regulation in V. alginolyticus.
群体感应 (QS) 系统是一种重要的细菌细胞间信号系统，可根据细胞密度响应调节各种基因的表达。在弧菌中，LuxR/AphA 是两个已确立的主要 QS 调节因子 (MQSR)，而 VqsA 最近被鉴定为第三个假定的 MQSR。作为一种新型的 LysR 型调节剂，VqsA 的调控基因和潜在的调控机制仍有待阐明。在这里，我们的研究表明，在生长阶段，碱性丝氨酸蛋白酶 (Asp) 的产量（溶藻弧菌的外毒素）依赖于 LuxR 和 VqsA。包括电泳迁移率变动分析 (EMSA) 以及 DNA 酶 I 足迹分析在内的各种体内和体外分析表明，VqsA 通过直接结合 asp 启动子区域的部分回文 29 个碱基对结合基序，正向调控 asp 的表达。此外，RNA-seq 分析验证了 VqsA 在生物体各种过程中的调控作用。总之，我们的数据表明，VqsA 正向调控外毒素和其他毒力相关基因的表达，是溶藻弧菌中 QS 调控所必需的。
