Transcriptional Regulation of the Type VI Secretion System 1 Genes by Quorum Sensing and ToxR in Vibrio parahaemolyticus.-猫眼课题宝

副溶血弧菌中群体感应和 ToxR 对 VI 型分泌系统 1 基因的转录调控

DOI：

10.3389/fmicb.2017.02005

发表时间：

2017

期刊：

Frontiers in microbiology

影响因子：

5.2

通讯作者：

中科院分区：

生物学2区

文献类型：

作者：

Zhang Y;Gao H;Osei-Adjei G;Zhang Y;Yang W;Yang H;Yin Z;Huang X;Zhou D

来源链接：

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5650642/

副溶血性弧菌是导致海鲜相关胃肠炎的主要原因，在染色体1和2上具有两个独立的T6 SS，即，T6 SS 1（VP 1386 -1420）和T6 SS 2（VPA 1025 -1046）。T6 SS 1含有至少7个推定的操纵子：VP 1386 -1387、VP 1388 -1390、VP 1392 -1391、VP 1393 -1406、VP 1400 -1406、VP 1409 -1407和VP 1410 -1420。副溶血弧菌AphA和OpaR是群体感应（quorum sensing，QS）系统的两个主要调节因子，分别在低细胞密度和高细胞密度下高表达。ToxR是弧菌家族中保守的膜结合毒力调节蛋白。在目前的工作中，我们表明，ToxR与AphA和OpaR协调抑制T6 SS 1在副溶血性弧菌中的表达。OpaR与VP 1388 -1390、VP 1400 -1406和VP 1409 -1407的启动子结合，抑制它们的转录，但它似乎以间接方式负调控VP 1393 -1406的转录。AphA对上述4个T6 SS 1操纵子的表达呈间接负调控。此外，ToxR与VP 1400 -1406和VP 1409 -1407的启动子结合以抑制其转录，但与VP 1388 -1390和VP 1393 -1406启动子存在间接相互作用。值得注意的是，ToxR的表达也表现为QS依赖性的方式，并且最高表达发生在LCD。同时，由于ToxR和QS的严格调节，T6 SS 1的最高表达发生在OD 600值为0.6至0.8时，表明T6 SS 1仅在对数生长中期发挥作用。这些观察结果为副溶血性弧菌中QS和ToxR调控T6 SS 1基因的分子机制提供了重要的见解。

Vibrio parahaemolyticus, the leading cause of seafood-associated gastroenteritis, harbors two separate T6SSs on chromosomes 1 and 2, i.e., T6SS1 (VP1386-1420) and T6SS2 (VPA1025-1046). T6SS1 contains at least 7 putative operons: VP1386-1387, VP1388-1390, VP1392-1391, VP1393-1406, VP1400-1406, VP1409-1407, and VP1410-1420. V. parahaemolyticus AphA and OpaR are the two master regulators of quorum sensing (QS) system that are highly expressed at low cell density and high cell density, respectively. ToxR is a membrane-bound virulence regulatory protein conserved across the Vibrio family. In the present work, we show that ToxR coordinates with AphA and OpaR to repress T6SS1 expression in V. parahaemolyticus. OpaR binds to the promoters of VP1388-1390, VP1400-1406, and VP1409-1407 to repress their transcription, but it appears to negatively regulate VP1393-1406 transcription in an indirect manner. By contrast, AphA negatively regulated the above four T6SS1 operons in an indirect manner. In addition, ToxR binds to the promoters of VP1400-1406 and VP1409-1407 to inhibit their transcription, but it presents an indirect interaction with VP1388-1390 and VP1393-1406 promoters. Notably, the expression of ToxR also manifested in a QS-dependent manner and the highest expression occurred at LCD. Meanwhile, the highest expression of T6SS1 occurred at an OD600 value of 0.6 to 0.8 due to the tight regulation of ToxR and QS, suggesting T6SS1 functions only during the mid-logarithmic growth phase. These observations provide significant insight into the molecular mechanism of T6SS1 gene regulation by QS and ToxR in V. parahaemolyticus.