Egile C, d'Hauteville H, Parsot C, Sansonetti P J
Unité de Pathogénie Microbienne Moléculaire, Unité 389 Institut National de la Santé et de la Recherche Médicale, Institut Pasteur, Paris, France.
Mol Microbiol. 1997 Mar;23(5):1063-73. doi: 10.1046/j.1365-2958.1997.2871652.x.
The spreading ability of Shigella flexneri, a facultative intracellular Gram-negative bacterium, within the host-cell cytoplasm is the result of directional assembly and accumulation of actin filaments at one pole of the bacterium. IcsA/VirG, the 120 kDa outer membrane protein that is required for intracellular motility, is located at the pole of the bacterium where actin polymerization occurs. Bacteria growing in laboratory media and within infected cells release a certain proportion of the surface-exposed IcsA after proteolytic cleavage. In this study, we report the characterization of the sopA gene which is located on the virulence plasmid and encodes the protein responsible for the cleavage of IcsA. The deduced amino acid sequence of SopA exhibits 60% identity with those of the OmpT and OmpP outer membrane proteases of Escherichia coli. The construction and phenotypic characterization of a sopA mutant demonstrated that SopA is required for exclusive polar localization of IcsA on the bacterial surface and proper expression of the motility phenotype in infected cells.
福氏志贺菌是一种兼性胞内革兰氏阴性菌，其在宿主细胞质内的扩散能力是细菌一极肌动蛋白丝定向组装和积累的结果。IcsA/VirG是一种120 kDa的外膜蛋白，是细胞内运动所必需的，位于发生肌动蛋白聚合的细菌极。在实验室培养基中生长以及在受感染细胞内生长的细菌，经蛋白水解切割后会释放一定比例的表面暴露IcsA。在本研究中，我们报道了位于毒力质粒上的sopA基因的特征，该基因编码负责切割IcsA的蛋白质。SopA推导的氨基酸序列与大肠杆菌的OmpT和OmpP外膜蛋白酶的氨基酸序列具有60%的同一性。sopA突变体的构建和表型特征表明，SopA是IcsA在细菌表面唯一极性定位以及在受感染细胞中正确表达运动表型所必需的。
