Chakravortty Dipshikha, Rohde Manfred, Jäger Lorenz, Deiwick Jörg, Hensel Michael
Institut für Klinische Mikrobiologie, Immunologie und Hygiene, FAU Erlangen-Nürnberg, Erlangen, Germany.
EMBO J. 2005 Jun 1;24(11):2043-52. doi: 10.1038/sj.emboj.7600676. Epub 2005 May 12.
The type III secretion system (T3SS) encoded by Salmonella Pathogenicity Island 2 (SPI2) is essential for virulence and intracellular proliferation of Salmonella enterica. We have previously identified SPI2-encoded proteins that are secreted and function as a translocon for the injection of effector proteins. Here, we describe the formation of a novel SPI2-dependent appendage structure in vitro as well as on the surface of bacteria that reside inside a vacuole of infected host cells. In contrast to the T3SS of other pathogens, the translocon encoded by SPI2 is only present singly or in few copies at one pole of the bacterial cell. Under in vitro conditions, appendages are composed of a filamentous needle-like structure with a diameter of 10 nm that was sheathed with secreted protein. The formation of the appendage in vitro is dependent on acidic media conditions. We analyzed SPI2-encoded appendages in infected cells and observed that acidic vacuolar pH was not required for induction of SPI2 gene expression, but was essential for the assembly of these structures and their function as translocon for delivery of effector proteins.
由沙门氏菌致病岛2（SPI2）编码的III型分泌系统（T3SS）对于肠炎沙门氏菌的毒力和细胞内增殖至关重要。我们之前已鉴定出SPI2编码的分泌蛋白，这些蛋白作为效应蛋白注射的转位体发挥作用。在此，我们描述了一种新型SPI2依赖性附属结构在体外以及在感染宿主细胞液泡内细菌表面的形成。与其他病原体的T3SS不同，SPI2编码的转位体仅单独或以少量拷贝存在于细菌细胞的一极。在体外条件下，附属物由直径为10纳米的丝状针状结构组成，该结构被分泌蛋白包裹。体外附属物的形成取决于酸性培养基条件。我们分析了感染细胞中SPI2编码的附属物，观察到酸性液泡pH值对于诱导SPI2基因表达不是必需的，但对于这些结构的组装及其作为效应蛋白递送转位体的功能至关重要。
