Inverted topology of the Toxoplasma gondii ROP5 rhoptry protein provides new insights into the association of the ROP2 protein family with the parasitophorous vacuole membrane
Inverted topology of the Toxoplasma gondii ROP5 rhoptry protein provides new insights into the association of the ROP2 protein family with the parasitophorous vacuole membrane
复制标题
DOI：
10.1111/j.1462-5822.2006.00767.x
复制
发表时间：
2007-01-01
影响因子：
3.4
通讯作者：
Dubremetz, Jean Francois
中科院分区：
文献类型：
--
作者：
El Hajj, Hiba;Lebrun, Maryse;Dubremetz, Jean Francois
刚地弓形虫是一种胞内寄生虫，通过寄生物液泡膜（PVM）与寄主细胞的细胞质分离。这个液泡是在宿主细胞入侵过程中形成的，在这个过程中，寄生虫的顶端细胞器释放与其膜相关的蛋白质。我们在此报道了rhophoy蛋白ROP5的特征，它是ROP2家族的新成员。与已知的其他ROP2家族蛋白不同，ROP5在转运到植物体的过程中不被加工。我们在这里表明，ROP5在侵袭期间分泌，并与PVM相关。利用感染细胞的差异通透性，我们发现ROP5将其c端暴露给宿主细胞质，与ROP2和ROP4相比，这对应于一个相反的拓扑结构。结合最近的建模数据表明，迄今为止被描述为跨膜的c端疏水结构域可能对应于埋藏在激酶相关蛋白催化结构域中的疏水螺旋，这些发现要求重新评估ROP2家族蛋白与PVM相关的当前观点。
Toxoplasma gondii, as many intracellular parasites, is separated from the cytosol of its host cell by a parasitophorous vacuole membrane (PVM). This vacuole forms during host cell invasion and parasite apical organelles named rhoptries discharge proteins that associate with its membrane during this process. We report here the characterization of the rhoptry protein ROP5, which is a new member of the ROP2 family. Contrasting with what is known for other ROP2 family proteins, ROP5 is not processed during trafficking to rhoptries. We show here that ROP5 is secreted during invasion and associates with the PVM. Using differential permeabilization of infected cells, we have shown that ROP5 exposes its C-terminus towards the host cell cytoplasm, which corresponds to a reverse topology compared with ROP2 and ROP4. Taken together with recent modelling data suggesting that the C-terminal hydrophobic domain hitherto described as transmembrane may correspond to a hydrophobic helix buried in the catalytic domain of kinase-related proteins, these findings call for a reappraisal of the current view of ROP2 family proteins association with the PVM.