Pathoadaptive Conditional Regulation of the Type VI Secretion System in Vibrio cholerae O1 Strains
Pathoadaptive Conditional Regulation of the Type VI Secretion System in Vibrio cholerae O1 Strains
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DOI：
10.1128/iai.05510-11
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发表时间：
2012-02-01
影响因子：
3.1
通讯作者：
Wai, Sun Nyunt
中科院分区：
文献类型：
--
作者：
Ishikawa, Takahiko;Sabharwal, Dharmesh;Wai, Sun Nyunt
革兰氏阴性菌最新发现的分泌途径是VI型分泌系统(T6SS)，它存在于许多物种中，被认为对非O1非O139霍乱弧菌在水环境中的生存至关重要。到目前为止，还不知道O1霍乱弧菌中是否存在具有功能活性的T6SS。O1霍乱弧菌是导致人类霍乱的原因。在这里，我们证明了在野生型霍乱弧菌O1株中存在具有功能活性的T6SS，T6SS底物Hcp的分泌证明了这一点，这需要在假定的vas基因簇中编码几个基因产物。我们的分析表明，霍乱弧菌O1野生型菌株A1552在高渗透压条件下生长时，T6SS被激活。当细菌在低温(23摄氏度)下生长时，T6SS也是活跃的，这表明该系统可能对细菌在环境中的生存至关重要。霍乱弧菌A1552菌株对一株大肠杆菌K-12菌株的菌间毒力试验表明，在高渗透压下其毒力明显增强，且依赖于hcp基因。有趣的是，我们发现新发现的渗透压调节蛋白Oscr对O1霍乱弧菌T6SS基因的表达和Hcp的分泌具有调节作用。
The most recently discovered secretion pathway in Gram-negative bacteria, the type VI secretion system (T6SS), is present in many species and is considered important for the survival of non-O1 non-O139 Vibrio cholerae in aquatic environments. Until now, it was not known whether there is a functionally active T6SS in wild-type V. cholerae O1 strains, the cause of cholera disease in humans. Here, we demonstrate the presence of a functionally active T6SS in wild-type V. cholerae O1 strains, as evidenced by the secretion of the T6SS substrate Hcp, which required several gene products encoded within the putative vas gene cluster. Our analyses showed that the T6SS of wild-type V. cholerae O1 strain A1552 was functionally activated when the bacteria were grown under high-osmolarity conditions. The T6SS was also active when the bacteria were grown under low temperature (23 degrees C), suggesting that the system may be important for the survival of the bacterium in the environment. A test of the interbacterial virulence of V. cholerae strain A1552 against an Escherichia coli K-12 strain showed that it was strongly enhanced under high osmolarity and that it depended on the hcp genes. Interestingly, we found that the newly recognized osmoregulatory protein OscR plays a role in the regulation of T6SS gene expression and secretion of Hcp from V. cholerae O1 strains.