Wolff C, Nisan I, Hanski E, Frankel G, Rosenshine I
Department of Molecular Genetics and Biotechnology, The Hebrew University, Faculty of Medicine, Jerusalem, Israel.
Mol Microbiol. 1998 Apr;28(1):143-55. doi: 10.1046/j.1365-2958.1998.00782.x.
Enteropathogenic Escherichia coli (EPEC) causes diarrhoea in young children. EPEC induces the formation of actin pedestal in infected epithelial cells. A type III protein secretion system and several proteins that are secreted by this system, including EspB, are involved in inducing the formation of the actin pedestals. We have demonstrated that contact of EPEC with HeLa cells is associated with the induction of production and secretion of EspB. Shortly after infection, EPEC initiates translocation of EspB, and EspB fused to the CyaA reporter protein (EspB-CyaA), into the host cell. The translocated EspB was distributed between the membrane and the cytoplasm of the host cell. Translocation was strongly promoted by attachment of EPEC to the host cell, and both attachment factors of EPEC, intimin and the bundle-forming pili, were needed for full translocation efficiency. Translocation and secretion of EspB and EspB-CyaA were abolished in mutants deficient in components of the type III protein secretion system, including sepA and sepB mutants. EspB-CyaA was secreted but not translocated by an espB mutant. These results indicate that EspB is both translocated and required for protein translocation by EPEC.
肠致病性大肠杆菌（EPEC）可导致幼儿腹泻。EPEC可诱导受感染上皮细胞中肌动蛋白基座的形成。III型蛋白分泌系统以及该系统分泌的几种蛋白，包括EspB，都参与了肌动蛋白基座的诱导形成。我们已经证明，EPEC与HeLa细胞的接触与EspB的产生和分泌诱导有关。感染后不久，EPEC启动EspB以及与CyaA报告蛋白融合的EspB（EspB-CyaA）向宿主细胞的转运。转运后的EspB分布在宿主细胞的膜和细胞质之间。EPEC与宿主细胞的附着强烈促进了转运，EPEC的两种附着因子，紧密素和束状菌毛，对于完全的转运效率都是必需的。在III型蛋白分泌系统组分缺陷的突变体中，包括sepA和sepB突变体，EspB和EspB-CyaA的转运和分泌被消除。EspB-CyaA可被分泌，但不能被espB突变体转运。这些结果表明，EspB既被转运，也是EPEC进行蛋白转运所必需的。
