SdiA, an Escherichia coli homologue of quorum-sensing regulators, controls the expression of virulence factors in enterohaemorrhagic Escherichia coli O157:H7
SdiA, an Escherichia coli homologue of quorum-sensing regulators, controls the expression of virulence factors in enterohaemorrhagic Escherichia coli O157:H7
复制标题
DOI：
10.1046/j.1365-2958.2000.02171.x
复制
发表时间：
2000-11-01
影响因子：
3.6
通讯作者：
Sasakawa, C
中科院分区：
文献类型：
--
作者：
Kanamaru, K;Kanamaru, K;Sasakawa, C
细菌中的群体感应系统是一个众所周知的调控系统，它以依赖于细胞密度的方式控制基因的表达，在大多数革兰氏阴性菌中，转录调节因子(LuxR同源)、信号合成酶(Luxi同源)和自身诱导物(酰基高丝氨酸内酯)是必不可少的。在本研究中，我们发现SdiA是EHEC O157：H7毒力因子EspD和内膜蛋白表达的负调控因子，SdiA过表达后在RNA水平上抑制EspD和内膜蛋白的表达，SdiA在其C末端有一个DNA结合基序，在体外可以与esp和eae基因的启动子区域结合。O157：H7在生长停滞期的培养上清液中积累了抑制EspD和内膜合成的胞外因子，在体内和体外与SdiA的N端部分结合，过量生产SdiA的N端部分表现出EspD和内膜的高转录，提示过量生产的N端部分通过滴定细胞外因子抑制了完整SdiA的活性。这些结果表明，包括SdiA蛋白在内的群体感应系统控制了O157：H7的定植。
The quorum-sensing system in bacteria is a well-known regulatory system that controls gene expression in a cell density-dependent manner, A transcriptional regulator (LuxR homologue), signal synthase (LuxI homologue) and autoinducer (acyl homoserine lactone) are indispensable for this system in most Gram-negative bacteria. In this study, we found that SdiA, an Escherichia coli LuxR homologue, is a negative regulator of the expression of virulence factors EspD and intimin in enterohaemorrhagic E. coli (EHEC) O157:H7, The expression of EspD and intimin was inhibited at the RNA level upon SdiA overexpression, SdiA has a DNA-binding motif in its C-terminal part and can bind to the promoter regions of the esp and eae genes in vitro. Extracellular factors, which accumulate in culture supernatants of O157:H7 at the stationary phase of growth and inhibit EspD and intimin synthesis, bind to the N-terminal part of SdiA in vivo and in vitro, O157:H7 overproducing the N-terminal part of SdiA exhibited hypertranscription of EspD and intimin, suggesting that the overproduced N-terminal part had inhibited the activity of intact SdiA through titration of the extracellular factors, These results indicate that a quorum-sensing system including the SdiA protein controls colonization by O157:H7.