Estévez Raúl, Schroeder Björn C, Accardi Alessio, Jentsch Thomas J, Pusch Michael
Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Universität Hamburg, Falkenried 94, D-20246 Hamburg, Germany.
Neuron. 2003 Apr 10;38(1):47-59. doi: 10.1016/s0896-6273(03)00168-5.
Crystal structures of bacterial CLC proteins were solved recently, but it is unclear to which level of detail they can be extrapolated to mammalian chloride channels. Exploiting the difference in inhibition by 9-anthracene carboxylic acid (9-AC) between ClC-0, -1, and -2, we identified a serine between helices O and P as crucial for 9-AC binding. Mutagenesis based on the crystal structure identified further residues affecting inhibitor binding. They surround a partially hydrophobic pocket close to the chloride binding site that is accessible from the cytoplasm, consistent with the observed intracellular block by 9-AC. Mutations in presumably Cl--coordinating residues yield additional insights into the structure and function of ClC-1. Our work shows that the structure of bacterial CLCs can be extrapolated with fidelity to mammalian Cl- channels.
细菌CLC蛋白的晶体结构最近已得到解析，但它们能在何种细节程度上外推至哺乳动物氯离子通道尚不清楚。利用9-蒽甲酸（9-AC）对ClC-0、-1和-2抑制作用的差异，我们确定了O螺旋和P螺旋之间的一个丝氨酸对9-AC结合至关重要。基于晶体结构的诱变鉴定出了其他影响抑制剂结合的残基。它们围绕着一个靠近氯离子结合位点的部分疏水口袋，该口袋可从细胞质进入，这与观察到的9-AC的细胞内阻断作用一致。推测的氯离子配位残基中的突变对ClC-1的结构和功能有了更多的深入了解。我们的工作表明，细菌CLC的结构可以如实地外推至哺乳动物氯离子通道。
