VqsA, a Novel LysR-Type Transcriptional Regulator, Coordinates Quorum Sensing (QS) and Is Controlled by QS To Regulate Virulence in the Pathogen Vibrio alginolyticus
VqsA, a Novel LysR-Type Transcriptional Regulator, Coordinates Quorum Sensing (QS) and Is Controlled by QS To Regulate Virulence in the Pathogen Vibrio alginolyticus
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VqsA 是一种新型 LysR 型转录调节因子，协调群体感应 (QS) 并受 QS 控制以调节病原体溶藻弧菌的毒力
DOI：
10.1128/aem.00444-18
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发表时间：
2018-06-01
影响因子：
4.4
通讯作者：
Wang, Qiyao
中科院分区：
文献类型：
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作者：
Gao, Xiating;Wang, Xuetong;Wang, Qiyao
群体感应（QS）系统控制细菌群体行为以响应细胞密度。在弧菌中，LuxR和AphA是两个控制基因表达的主QS调节剂（MQSRs），以响应高或低细胞密度。参与这两种mqsr和QS途径调控的其他调控因子仍有待确定。在这里，我们进行了基于细菌单杂交（B1H）检测的转录因子（TFs）筛选，从鱼类病原体褐藻溶解弧菌编码的285个转录因子文库中鉴定出可以直接调节luxR和aphA表达的转录因子。共鉴定出7个tf与luxR和aphA的启动子结合。在这些tf中，新的lysr型转录调节因子（ltr） VqsA可以激活LuxR并抑制AphA的转录。同时，LuxR和AphA分别对vqsA表达产生反馈抑制和激活作用，说明vqsA协调QS，也受QS的调控。此外，VqsA通过直接结合自身启动子区域抑制自身表达。通过电泳迁移位移分析（emsa）和dna酶I足迹分析发现luxR和aphA启动子区域的VqsA结合位点以及VqsA基因中luxR、aphA和VqsA的结合位点。最后，VqsA被证实在qs调控的表型中发挥重要作用，即依赖于VI型分泌系统2 （T6SS2）的细菌间竞争、生物膜形成、外毒素产生和藻毒弧菌的体内毒力。综上所述，我们的数据表明VqsA是溶藻弧菌中重要的QS调节剂。研究群体感应（quorum sensing， QS）系统的调节机制将有助于理解细菌的发病机制和识别有效的群体感应干扰（quorum sensing， QSI）靶点。在这里，我们系统地筛选了调节主QS调控因子（MQSRs） LuxR和AphA表达的转录因子（TFs），并鉴定了一种新的lysr型转录调控因子VqsA。我们的数据阐明了介导LuxR、AphA和VqsA之间相互作用的机制，以及这些调节因子对QS表达和输出的影响。vqsA破坏导致毒力基因表达受损，表明vqsA在QS调控和发病中起重要作用，可能是第三个参与弧菌感知环境信号以协调QS反应的MQSR。本研究将有助于制定干扰QS的策略，有效控制这一困扰水产养殖业的病原体。
ABSTRACT The quorum sensing (QS) system controls bacterial group behaviors in response to cell density. In vibrios, LuxR and AphA are two master QS regulators (MQSRs) controlling gene expression in response to high or low cell density. Other regulators involved in the regulation of these two MQSRs and QS pathways remain to be determined. Here, we performed bacterial one-hybrid (B1H)-assay-based screens of transcriptional factors (TFs) to identify TFs that can directly regulate the expression of luxR and aphA from a library of 285 TFs encoded by the fish pathogen Vibrio alginolyticus. A total of 7 TFs were identified to bind to the promoters of both luxR and aphA. Among these TFs, the novel LysR-type transcriptional regulator (LTTR) VqsA could activate LuxR and repress AphA transcription. Meanwhile, LuxR and AphA exerted feedback inhibition and activation of vqsA expression, respectively, indicating that VqsA coordinates QS and is also regulated by QS. In addition, VqsA inhibited its own expression by directly binding to its own promoter region. The VqsA-binding sites in the promoter regions of luxR and aphA as well as the binding sites of LuxR, AphA, and VqsA in the vqsA gene were uncovered by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting analysis. Finally, VqsA was verified to play essential roles in QS-regulated phenotypes, i.e., type VI secretion system 2 (T6SS2)-dependent interbacterial competition, biofilm formation, exotoxin production, and in vivo virulence of V. alginolyticus. Collectively, our data showed that VqsA is an important QS regulator in V. alginolyticus. IMPORTANCE Investigation of the mechanism of regulation of quorum sensing (QS) systems will facilitate an understanding of bacterial pathogenesis and the identification of effective QS interference (QSI) targets. Here, we systematically screened transcriptional factors (TFs) that modulate the expression of the master QS regulators (MQSRs) LuxR and AphA, and a novel LysR-type transcriptional regulator, VqsA, was identified. Our data illuminated the mechanisms mediating the interaction among LuxR, AphA, and VqsA as well as the effects of these regulators on the expression and output of QS. The impaired expression of virulence genes as a result of vqsA disruption demonstrated that VqsA is an important player in QS regulation and pathogenesis and may be the third MQSR involved in sensing environmental signals by vibrios to coordinate QS responses. This study will facilitate the development of strategies to interfere with QS and effectively control this pathogen that plagues the aquaculture industry.