Crystal structure of the soluble form of the redox-regulated chloride ion channel protein CLIC4
Crystal structure of the soluble form of the redox-regulated chloride ion channel protein CLIC4
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DOI：
10.1111/j.1742-4658.2005.04909.x
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发表时间：
2005-10-01
期刊：
影响因子：
5.4
通讯作者：
Curmi, PMG
中科院分区：
文献类型：
--
作者：
Littler, DR;Assaad, NN;Curmi, PMG
CLIC 4是细胞内氯离子通道蛋白CLIC家族的成员，其结构已通过X射线晶体学在1.8埃分辨率下确定。该蛋白是单体的，并且它在结构上类似于CLIC 1，属于GST折叠类。CLIC 1和CLIC 4的结构之间的差异定位于谷氧还蛋白样N-末端结构域中的螺旋2，该结构域先前已被证明在氧化后CLIC 1中发生显著的结构变化。该区域的结构差异与序列差异相关，其中CLIC 1序列似乎是该家族的非典型序列。纯化的重组野生型CLIC 4显示与人工脂质双层结合，当与人工脂质体结合时诱导氯离子流出电流，并在人工双层中产生电导为30 pS的离子通道。通过CLIC 4的氧化增强膜结合，而在还原剂存在下通过尖端-浸入电生理学没有观察到通道。因此，重组CLIC 4似乎能够在不存在任何伴侣蛋白的情况下形成氧化还原调节的离子通道。
The structure of CLIC4, a member of the CLIC family of putative intracellular chloride ion channel proteins, has been determined at 1.8 angstrom resolution by X-ray crystallography. The protein is monomeric and it is structurally similar to CLIC1, belonging to the GST fold class. Differences between the structures of CLIC1 and CLIC4 are localized to helix 2 in the glutaredoxin-like N-terminal domain, which has previously been shown to undergo a dramatic structural change in CLIC1 upon oxidation. The structural differences in this region correlate with the sequence differences, where the CLIC1 sequence appears to be atypical of the family. Purified, recombinant, wild-type CLIC4 is shown to bind to artificial lipid bilayers, induce a chloride efflux current when associated with artificial liposomes and produce an ion channel in artificial bilayers with a conductance of 30 pS. Membrane binding is enhanced by oxidation of CLIC4 while no channels were observed via tip-dip electrophysiology in the presence of a reducing agent. Thus, recombinant CLIC4 appears to be able to form a redox-regulated ion channel in the absence of any partner proteins.