Molecular principles of assembly, activation, and inhibition in epithelial sodium channel
Molecular principles of assembly, activation, and inhibition in epithelial sodium channel
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DOI：
10.7554/elife.59038
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发表时间：
2020-07-30
期刊：
影响因子：
7.7
通讯作者：
Baconguis, Isabelle
中科院分区：
文献类型：
--
作者：
Noreng, Sigrid;Posert, Richard;Baconguis, Isabelle
上皮钠通道（ENaCs）中异聚体组装的分子基础以及Na+自抑制与蛋白酶敏感性之间的联系尚不完全清楚。之前，我们证明了ENaC亚基- α， β和γ -在细胞外与蛋白酶敏感的GRIP结构域（Noreng et al., 2018）从细胞外观察时以逆时针结构组装。在这里，我们描述了在3埃低温电子显微镜下分解的ENaC的结构。我们发现精确的结构域排列和互补的氢键网络的结合定义了亚基排列。此外，我们确定a亚基具有由手指和GRIP结构域组成的主要功能模块。该模块由α 2螺旋分岔，分为两个不同的调节位点：Na+和抑制肽。抑制肽的去除通过α 2螺旋干扰Na+位点，突出了α 2螺旋在调节ENaC功能中的关键作用。
The molecular bases of heteromeric assembly and link between Na+ self-inhibition and protease-sensitivity in epithelial sodium channels (ENaCs) are not fully understood. Previously, we demonstrated that ENaC subunits - alpha, beta, and gamma- assemble in a counterclockwise configuration when viewed from outside the cell with the protease-sensitive GRIP domains in the periphery (Noreng et al., 2018). Here we describe the structure of ENaC resolved by cryo-electron microscopy at 3 angstrom. We find that a combination of precise domain arrangement and complementary hydrogen bonding network defines the subunit arrangement. Furthermore, we determined that the a subunit has a primary functional module consisting of the finger and GRIP domains. The module is bifurcated by the alpha 2 helix dividing two distinct regulatory sites: Na+ and the inhibitory peptide. Removal of the inhibitory peptide perturbs the Na+ site via the alpha 2 helix highlighting the critical role of the alpha 2 helix in regulating ENaC function.