Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids
Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids
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DOI：
10.1126/sciadv.aax3157
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发表时间：
2020-02-01
期刊：
影响因子：
13.6
通讯作者：
Oshima, Atsunori
中科院分区：
文献类型：
--
作者：
Burendei, Batuujin;Shinozaki, Ruriko;Oshima, Atsunori
间隙连接形成具有大孔径的细胞间导管，其闭合和开放状态调节相邻细胞之间的通讯。然而，间隙连接关闭机制的结构基础仍然不确定。在这里，我们展示了未对接半通道形式的秀丽隐杆线虫 innexin-6 (INX-6) 间隙连接蛋白的冷冻电子显微镜结构。在野生型 INX-6 半通道的纳米盘重建结构中，平坦的双层密度阻塞了通道孔。比较去污剂中野生型 INX-6 和纳米盘重建的氨基末端缺失突变体的半通道结构表明，脂质介导的氨基末端重排和孔阻塞发生在纳米盘重建时。结合分子动力学模拟和电生理学功能测定，我们的结果提供了对两个半通道对接之前脂质双层中 INX-6 半通道关闭的深入了解。
Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.