Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
J Biol Chem. 2010 May 21;285(21):16360-8. doi: 10.1074/jbc.M110.100669. Epub 2010 Mar 24.
Effectors of the type III secretion systems (T3SS) are key elements in the interaction between many Gram-negative pathogens and their hosts. SlrP is an effector that is translocated into the eukaryotic host cell through the two virulence-associated T3SS of Salmonella enterica. We found previously that this effector is an E3 ubiquitin ligase for mammalian thioredoxin. Here, we identified ERdj3, an endoplasmic reticulum lumenal chaperone of the Hsp40/DnaJ family, as a new target for SlrP. Experiments with truncated forms of ERdj3 showed that domain II was essential for the interaction with SlrP. Confocal microscopy and subcellular fractionation demonstrated that, in transfected HeLa cells, SlrP was partially located in the endoplasmic reticulum. The presence of SlrP interfered with the binding of ERdj3 to a denatured substrate. Taken together, these data suggest that the role of SlrP in the interaction between Salmonella and the host cell is exerted through the modulation of the function of two independent targets: thioredoxin in the cytosol, and ERdj3 in the endoplasmic reticulum.
III 型分泌系统（T3SS）的效应器是许多革兰氏阴性病原体与其宿主相互作用的关键要素。SlrP 是一种通过沙门氏菌属的两种与毒力相关的 T3SS 易位到真核宿主细胞的效应物。我们之前发现，这种效应物是哺乳动物硫氧还蛋白的 E3 泛素连接酶。在这里，我们鉴定出 ERdj3，即 Hsp40/DnaJ 家族内质网腔腔伴侣，是 SlrP 的一个新靶标。用 ERdj3 的截断形式进行的实验表明，结构域 II 对于与 SlrP 的相互作用是必需的。共聚焦显微镜和亚细胞分级分离表明，在转染的 HeLa 细胞中，SlrP 部分定位于内质网。SlrP 的存在干扰了 ERdj3 与变性底物的结合。总之，这些数据表明，SlrP 在沙门氏菌与宿主细胞相互作用中的作用是通过调节两个独立靶标的功能来发挥的：细胞质中的硫氧还蛋白和内质网中的 ERdj3。
