Global twisting motion of single molecular KcsA potassium channel upon Gating
Global twisting motion of single molecular KcsA potassium channel upon Gating
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DOI：
10.1016/j.cell.2007.11.040
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发表时间：
2008-01-11
期刊：
影响因子：
64.5
通讯作者：
Oiki, Shigetoshi
中科院分区：
文献类型：
--
作者：
Shimizu, Hirofumi;Iwamoto, Masayuki;Oiki, Shigetoshi
离子通道是信号转导分子，可开关离子渗透通路（门控）。几种钾通道的晶体结构显示出开放和封闭的构象，提供了门控状态的静态图像。本研究在单分子水平上研究了KcsA钾离子通道的构象变化。用白色x射线照射附着金纳米晶体的KcsA通道，实时跟踪纳米晶体衍射光斑的运动。浇注后，KcsA通道绕孔轴扭曲。这些构象变化被一种开放通道阻滞剂四丁基铵所阻止。在几十度范围内的顺时针和逆时针的随机扭曲起源于跨膜域，并传递到细胞质域。这种耦合表明跨膜和细胞质结构域之间存在机械相互作用。
Ion channels are signal transduction molecules that switch ion permeation pathways on and off (gating). Crystal structures of several kinds of potassium channels have revealed open and closed conformations, which provide static pictures of gating status. Here we studied KcsA potassium channels undergoing conformational changes at the single-molecule level. A KcsA channel with a gold nanocrystal attached was irradiated by white X-rays and motions of the diffraction spot from the nanocrystal were tracked in real time. Upon gating, the KcsA channels twisted around the axis of the pore. These conformational changes were prevented by an open-channel blocker, tetrabuthylammonium. Random clockwise and counterclockwise twisting in the range of several tens of degrees originated in the transmembrane domain and was transmitted to the cytoplasmic domain. This coupling suggests a mechanical interplay between the transmembrane and cytoplasmic domains.