Molecular insights into the human CLC-7/Ostm1 transporter
Molecular insights into the human CLC-7/Ostm1 transporter
复制标题
对人类 CLC-7/Ostm1 转运蛋白的分子见解
DOI：
10.1126/sciadv.abb4747
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发表时间：
2020
期刊：
影响因子：
13.6
通讯作者：
Yang Maojun
中科院分区：
文献类型：
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作者：
Zhang Sensen;Liu Yang;Zhang Bing;Zhou Jun;Li Tianyu;Liu Zhiqiang;Li Yang;Yang Maojun
人类CLC-7/Ostm1转运体的结构和功能研究有助于了解CLC蛋白的缓慢门控。CLC家族蛋白通过跨膜转运氯离子维持细胞膜电位，调节经上皮Cl -转运，并控制不同细胞器间囊内pH值。CLC-7/Ostm1是一种电致Cl−/H+反转运蛋白，主要存在于溶酶体和破骨细胞褶膜中。人CLC-7/Ostm1基因突变可导致溶酶体贮积障碍和严重的骨质疏松症。在这里，我们展示了人类CLC-7/Ostm1复合物的冷冻电镜（cryo-EM）结构，并揭示了高度糖基化的Ostm1像位于CLC-7上方的盖子一样起作用，并在膜内与CLC-7广泛相互作用。我们的复杂结构揭示了CLC-7的氨基端，TMD和CBS结构域之间的功能关键结构域界面。结构分析和电生理研究表明，区域相互作用界面影响CLC-7/Ostm1的慢门控动力学。因此，我们的研究加深了对CLC-7/Ostm1转运体的认识，并为疾病相关突变的分子基础提供了见解。
Structural and functional studies of the human CLC-7/Ostm1 transporter help understand the slow gating of CLC proteins. CLC family proteins translocate chloride ions across cell membranes to maintain the membrane potential, regulate the transepithelial Cl− transport, and control the intravesicular pH among different organelles. CLC-7/Ostm1 is an electrogenic Cl−/H+ antiporter that mainly resides in lysosomes and osteoclast ruffled membranes. Mutations in human CLC-7/Ostm1 lead to lysosomal storage disorders and severe osteopetrosis. Here, we present the cryo–electron microscopy (cryo-EM) structure of the human CLC-7/Ostm1 complex and reveal that the highly glycosylated Ostm1 functions like a lid positioned above CLC-7 and interacts extensively with CLC-7 within the membrane. Our complex structure reveals a functionally crucial domain interface between the amino terminus, TMD, and CBS domains of CLC-7. Structural analyses and electrophysiology studies suggest that the domain interaction interfaces affect the slow gating kinetics of CLC-7/Ostm1. Thus, our study deepens understanding of CLC-7/Ostm1 transporter and provides insights into the molecular basis of the disease-related mutations.