Structural basis of guanine nucleotide exchange for Rab11 by SH3BP5
Structural basis of guanine nucleotide exchange for Rab11 by SH3BP5
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DOI：
10.26508/lsa.201900297
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发表时间：
2019-04-01
影响因子：
4.4
通讯作者：
Fukai, Shuya
中科院分区：
文献类型：
--
作者：
Goto-Ito, Sakurako;Morooka, Nobukatsu;Fukai, Shuya
Rab GT3家族是真核细胞中膜运输的主要调节因子。Rab 11亚家族在胞吐、内体再循环和胞质分裂等特定的运输事件中起着重要作用。SH 3BP 5和SH 3BP 5-like（SH 3BP 5L）蛋白最近被发现作为Rab 11的鸟嘌呤核苷酸交换因子（GEF）。在这里，我们报告的晶体结构的SH 3BP 5 GEF结构域单独和其复杂的Rab 11 a。SH 3BP 5呈现包括两个盘绕的线圈的V形结构。由α 1和α 4组成的卷曲螺旋仅负责Rab 11 a结合和GEF活性。SH 3BP 5拉出Rab 11 a的开关I并使其变形，以便于从Rab 11 a释放GDP。SH 3BP 5与Rab 11 a的N端区域、开关I、开关间和开关II相互作用。SH 3BP 5和SH 3BP 5L定位于Rab 11阳性再循环内体，并对所有Rab 11家族显示GEF活性，但对Rab 14不显示GEF活性。结合定点诱变的基于双标记的GEF测定揭示了SH 3BP 5和Rab 11家族蛋白之间对于再循环内体上的GEF反应的重要相互作用。
The Rab GTPase family is a major regulator of membrane traffic in eukaryotic cells. The Rab11 subfamily plays important roles in specific trafficking events such as exocytosis, endosomal recycling, and cytokinesis. SH3BP5 and SH3BP5-like (SH3BP5L) proteins have recently been found to serve as guanine nucleotide exchange factors (GEF) for Rab11. Here, we report the crystal structures of the SH3BP5 GEF domain alone and its complex with Rab11a. SH3BP5 exhibits a V-shaped structure comprising two coiled coils. The coiled coil composed of alpha 1, and alpha 4 is solely responsible for the Rab11a binding and GEF activity. SH3BP5 pulls out and deforms switch I of Rab11a so as to facilitate the GDP release from Rab11a. SH3BP5 interacts with the N-terminal region, switch I, interswitch, and switch II of Rab11a. SH3BP5 and SH3BP5L localize to Rab11-positive recycling endosomes and show GEF activity for all of the Rab11 family but not for Rab14. Fluorescence-based GEF assays combined with site-directed mutagenesis reveal the essential interactions between SH3BP5 and Rab11 family proteins for the GEF reaction on recycling endosomes.