Crane J K, McNamara B P, Donnenberg M S
Division of Infectious Diseases, State University of New York at Buffalo, Room 109 Biomedical Research Bldg., 3435 Main St., Buffalo, NY 14214, USA.
Cell Microbiol. 2001 Apr;3(4):197-211. doi: 10.1046/j.1462-5822.2001.00103.x.
Enteropathogenic Escherichia coli (EPEC) causes diarrhoea in children in developing countries. Many EPEC genes involved in virulence are contained within the locus of enterocyte effacement (LEE), a large pathogenicity island. One of the genes at the far righthand end of the LEE encodes EspF, an EPEC secreted protein of unknown function. EspF, like the other Esps, is a substrate for secretion by the type III secretory system. Previous studies found that an espF mutant behaved as wild type in assays of adherence, invasion, actin condensation and tyrosine phosphorylation. As EPEC can kill host cells, we tested esp gene mutants for host cell killing ability. The espF mutant was deficient in host cell killing despite having normal adherence. The addition of purified EspF to tissue culture medium did not cause any damage to host cells, but expression of espF in COS or HeLa cells caused cell death. The mode of cell death in cells transfected with espF appeared to be pure apoptosis. EspF appears to be an effector of host cell death in epithelial cells; its proline-rich structure suggests that it may act by binding to SH3 domains or EVH1 domains of host cell signalling proteins.
肠致病性大肠杆菌（EPEC）在发展中国家的儿童中引起腹泻。许多与毒力相关的EPEC基因包含在肠细胞脱落位点（LEE）内，LEE是一个大型致病岛。LEE最右端的基因之一编码EspF，一种功能未知的EPEC分泌蛋白。与其他Esps一样，EspF是III型分泌系统分泌的底物。先前的研究发现，espF突变体在黏附、侵袭、肌动蛋白凝聚和酪氨酸磷酸化试验中表现与野生型相同。由于EPEC可杀死宿主细胞，我们检测了esp基因突变体的宿主细胞杀伤能力。尽管espF突变体黏附正常，但它在宿主细胞杀伤方面存在缺陷。向组织培养基中添加纯化的EspF不会对宿主细胞造成任何损伤，但在COS或HeLa细胞中表达espF会导致细胞死亡。转染espF的细胞中的细胞死亡模式似乎是单纯的凋亡。EspF似乎是上皮细胞中宿主细胞死亡的效应器；其富含脯氨酸的结构表明它可能通过与宿主细胞信号蛋白的SH3结构域或EVH1结构域结合而起作用。
