A non-canonical GTPase interaction enables ORP1L-Rab7-RILP complex formation and late endosome positioning
A non-canonical GTPase interaction enables ORP1L-Rab7-RILP complex formation and late endosome positioning
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非典型 GTPase 相互作用使 ORP1L-Rab7-RILP 复合物形成和晚期内体定位
DOI：
10.1074/jbc.ra118.001854
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发表时间：
2018-09-07
影响因子：
4.8
通讯作者：
Liang, Huanhuan
中科院分区：
文献类型：
--
作者：
Ma, Xinli;Liu, Kai;Liang, Huanhuan
内体转运代表细胞内运输和信号转导的主要模式，因此必须严格控制。控制内体定位的分子过程利用几种大的蛋白质复合物，其中之一含有小的GTTRab 7、Rab-interacting lysosomal protein（RILP）和oxysterol-binding protein-related protein 1（ORP 1 L）。已知Rab 7通过称为效应子相互作用开关区的典型结合位点与RILP相互作用，但目前尚不清楚Rab 7如何与ORP 1 L相互作用，限制了我们对整个过程的理解。在这里，我们报告的Rab 7-ORP 1 L相互作用的结构和生化研究。我们发现，与之前的研究相反，Rab 7与ORP 1 L的N末端锚蛋白重复结构域（ARDN）之间的相互作用不依赖于Rab 7的GTP或GDP结合状态。此外，我们发现Rab 7通过一个独特的区域与ORP 1 L ARDN相互作用，该区域由螺旋3（α3）和310-螺旋2（η2）组成。这种结构使得典型的效应子相互作用开关区域可用于RILP结合，从而允许形成ORP 1 L-Rab 7-RILP三方复合物。ORP 1 L和Rab 7之间相互作用界面的突变破坏了ORP 1 L-Rab 7-RILP调节晚期内体定位的能力。总的来说，我们的结果再次证明了GTdR及其效应物之间相互作用的多功能性。
Endosomal transport represents the primary mode for intracellular trafficking and signaling transduction and thus has to be tightly controlled. The molecular processes controlling the endosomal positioning utilize several large protein complexes, one of which contains the small GTPase Rab7, Rab-interacting lysosomal protein (RILP), and oxysterol-binding protein–related protein 1 (ORP1L). Rab7 is known to interact with RILP through a canonical binding site termed the effector-interacting switch region, but it is not clear how Rab7 interacts with ORP1L, limiting our understanding of the overall process. Here, we report structural and biochemical investigation of the Rab7-ORP1L interaction. We found that, contrary to prior studies, the interaction between Rab7 and the N-terminal ankyrin repeat domain (ARDN) of ORP1L is independent of Rab7's GTP- or GDP-binding state. Moreover, we show that Rab7 interacts with ORP1L ARDN via a unique region consisting of helix3 (α3) and 310-helix 2 (η2). This architecture leaves the canonical effector-interacting switch regions available for RILP binding and thus allows formation of the ORP1L-Rab7-RILP tripartite complex. Mutational disruption of the interacting interface between ORP1L and Rab7 compromised the ability of ORP1L-Rab7-RILP to regulate the late endosome positioning. Collectively, our results again manifested the versatility in the interaction between GTPase and its effector.