C9orf72 复合物的 ARF GAP 活性和特异性的结构基础。
Structural basis for the ARF GAP activity and specificity of the C9orf72 complex.
机构信息
School of Medicine, Southern University of Science and Technology, Shenzhen, China.
Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
出版信息
Nat Commun. 2021 Jun 18;12(1):3786. doi: 10.1038/s41467-021-24081-0.
Mutation of C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontal temporal degeneration (FTD), which is attributed to both a gain and loss of function. C9orf72 forms a complex with SMCR8 and WDR41, which was reported to have GTPase activating protein activity toward ARF proteins, RAB8A, and RAB11A. We determined the cryo-EM structure of ARF1-GDP-BeF bound to C9orf72:SMCR8:WDR41. The SMCR8 and C9orf72 domains form the binding pocket for ARF1. One face of the C9orf72 domain holds ARF1 in place, while the SMCR8 positions the catalytic finger Arg147 in the ARF1 active site. Mutations in interfacial residues of ARF1 and C9orf72 reduced or eliminated GAP activity. RAB8A GAP required ~10-fold higher concentrations of the C9orf72 complex than for ARF1. These data support a specific function for the C9orf72 complex as an ARF GAP. The structure also provides a model for the active forms of the longin domain GAPs of FLCN and NPRL2 that regulate the Rag GTPases of the mTORC1 pathway.
C9ORF72 突变是肌萎缩侧索硬化症 (ALS) 和额颞叶变性 (FTD) 的最常见遗传原因，这归因于其功能的获得和丧失。C9orf72 与 SMCR8 和 WDR41 形成复合物，据报道该复合物对 ARF 蛋白、RAB8A 和 RAB11A 具有 GTP 酶激活蛋白活性。我们确定了与 C9orf72:SMCR8:WDR41 结合的 ARF1-GDP-BeF 的冷冻电镜结构。SMCR8 和 C9orf72 结构域形成了 ARF1 的结合口袋。C9orf72 结构域的一个面将 ARF1 固定在适当位置，而 SMCR8 将催化指 Arg147 定位在 ARF1 的活性位点上。ARF1 和 C9orf72 界面残基的突变降低或消除了 GAP 活性。RAB8A GAP 比 ARF1 更需要高 10 倍浓度的 C9orf72 复合物。这些数据支持 C9orf72 复合物作为 ARF GAP 的特定功能。该结构还为调节 mTORC1 途径 Rag GTPases 的 FLCN 和 NPRL2 的长链域 GAP 的活性形式提供了模型。
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