Cryo-EM structure of the ATP-sensitive potassium channel illuminates mechanisms of assembly and gating
Cryo-EM structure of the ATP-sensitive potassium channel illuminates mechanisms of assembly and gating
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DOI：
10.7554/elife.24149
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发表时间：
2017-01-16
期刊：
影响因子：
7.7
通讯作者：
Shyng, Show-Ling
中科院分区：
文献类型：
--
作者：
Martin, Gregory M.;Yoshioka, Craig;Shyng, Show-Ling
K-ATP 通道是将细胞能量与膜兴奋性耦合的代谢传感器。在胰腺 β 细胞中，SUR1 和 Kir6.2 形成的通道调节胰岛素分泌，是磺酰脲类抗糖尿病药物的靶点。在这里，我们使用冷冻电镜来阐明通道组装和门控的结构基础。在 ATP 和磺酰脲格列本脲存在下测定的结构，在类似于 6 埃的分辨率下揭示了一个封闭的 Kir6.2 四聚体核心，其中有四个外围 SUR1，每个 SUR1 通过其 N 端跨膜结构域 (TMD0) 锚定到 Kir6.2。 TMD0（TMD0 后面的环）与拟议的 PIP2 结合位点附近的 Kir6.2 之间复杂的相互作用，以及观察到 ATP 密度的位置，表明 SUR1 可能有助于 ATP 和 PIP2 结合，从而增强 Kir6.2 对两者的敏感性。 SUR1-ABC 核心被发现处于一种不寻常的向内构象，其中两个核苷酸结合域沿着两倍对称轴错位，揭示了格列本脲抑制通道活性的可能机制。
K-ATP channels are metabolic sensors that couple cell energetics to membrane excitability. In pancreatic beta-cells, channels formed by SUR1 and Kir6.2 regulate insulin secretion and are the targets of antidiabetic sulfonylureas. Here, we used cryo-EM to elucidate structural basis of channel assembly and gating. The structure, determined in the presence of ATP and the sulfonylurea glibenclamide, at similar to 6 angstrom resolution reveals a closed Kir6.2 tetrameric core with four peripheral SUR1s each anchored to a Kir6.2 by its N-terminal transmembrane domain (TMD0). Intricate interactions between TMD0, the loop following TMD0, and Kir6.2 near the proposed PIP2 binding site, and where ATP density is observed, suggest SUR1 may contribute to ATP and PIP2 binding to enhance Kir6.2 sensitivity to both. The SUR1-ABC core is found in an unusual inward-facing conformation whereby the two nucleotide binding domains are misaligned along a two-fold symmetry axis, revealing a possible mechanism by which glibenclamide inhibits channel activity.