The regulatory mechanism of ion permeation through a channelrhodopsin derived from Mesostigma viride (MvChR1)
The regulatory mechanism of ion permeation through a channelrhodopsin derived from Mesostigma viride (MvChR1)
复制标题
源自绿色中柱的视紫质通道蛋白 (MvChR1) 的离子渗透调节机制
DOI：
10.1039/c5pp00290g
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发表时间：
2016
影响因子：
3.1
通讯作者：
Yawo H
中科院分区：
文献类型：
--
作者：
Watanabe S;Ishizuka T;Hososhima S;Zamani A;Hoque MR;Yawo H
通道视紫红质（CrChR）-2的跨膜（TM）-2的5个谷氨酸（E）残基在ChR家族的几个成员中是保守的。其中之一，E97，一个非极性丙氨酸（E97 A）的点突变降低了光电流幅度，而不影响其他光电流特性。该位置的电荷也是通道的Gd 3+依赖性阻断的决定因素。因此，人们认为E97与水合阳离子相互作用以促进其渗透，并且这些残基是Gd 3+的主要结合位点。然而，Mesostigma viride的MvChR 1的对应位置是丙氨酸。在这里，我们研究了MvChR 1的离子渗透和Gd 3+依赖性通道阻滞。我们发现，Gd 3+的高亲和力结合位点在MvChR 1中是不存在的，但依赖于在这个位置的负性。然而，通过通道的离子渗透在该位置处被负电荷显著干扰。基于这些发现，提出离子可以通过孔，与该位置的相互作用最小。
The five glutamate (E) residues of transmembrane (TM)-2 of channelrhodopsin (CrChR)-2 are conserved among several members of the ChR family. A point mutation of one of them, E97, to a nonpolar alanine (E97A) reduced the photocurrent amplitude without influencing other photocurrent properties. The charge at this position is also the determinant of the Gd3+-dependent block of the channel. It has thus been suggested that E97 interacts with hydrated cations to facilitate their permeation and that these residues are the primary binding sites of Gd3+. However, the counterpart of this position is alanine for MvChR1 fromMesostigma viride. Here we investigated the ion permeation and the Gd3+-dependent channel block of MvChR1. We found that the high-affinity binding site of Gd3+was absent in MvChR1, but was dependent on the negativity at this position. However, the ion permeation through the channel was markedly interfered with a negative charge at this position. Based on these findings, it is proposed that the ions can pass through the pore with minimal interaction with this position.