Wai Sun Nyunt, Lindmark Barbro, Söderblom Tomas, Takade Akemi, Westermark Marie, Oscarsson Jan, Jass Jana, Richter-Dahlfors Agneta, Mizunoe Yoshimitsu, Uhlin Bernt Eric
Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.
Cell. 2003 Oct 3;115(1):25-35. doi: 10.1016/s0092-8674(03)00754-2.
The ClyA protein is a pore-forming cytotoxin expressed by Escherichia coli and some other enterobacteria. It confers cytotoxic activity toward mammalian cells, but it has remained unknown how ClyA is surface exposed and exported from bacterial cells. Outer-membrane vesicles (OMVs) released from the bacteria were shown to contain ClyA protein. ClyA formed oligomeric pore assemblies in the OMVs, and the cytotoxic activity toward mammalian cells was considerably higher than that of ClyA protein purified from the bacterial periplasm. The redox status of ClyA correlated with its ability to form the oligomeric pore assemblies. In bacterial cells with a defective periplasmic disulphide oxidoreductase system, the ClyA protein was phenotypically expressed in a constitutive manner. The results define a vesicle-mediated transport mechanism in bacteria, and our findings show that the localization of proteins to OMVs directly may contribute to the activation and delivery of pathogenic effector proteins.
ClyA蛋白是一种由大肠杆菌和其他一些肠道细菌表达的成孔细胞毒素。它对哺乳动物细胞具有细胞毒性活性，但ClyA如何在细菌细胞表面暴露并输出仍不清楚。研究表明，细菌释放的外膜囊泡（OMV）中含有ClyA蛋白。ClyA在OMV中形成寡聚孔组装体，其对哺乳动物细胞的细胞毒性活性远高于从细菌周质中纯化的ClyA蛋白。ClyA的氧化还原状态与其形成寡聚孔组装体的能力相关。在周质二硫键氧化还原酶系统有缺陷的细菌细胞中，ClyA蛋白以组成型方式表型表达。这些结果定义了细菌中一种囊泡介导的运输机制，我们的研究结果表明，蛋白质直接定位于OMV可能有助于致病效应蛋白的激活和传递。
