Structure of a glycerol-conducting channel and the basis for its selectivity
Structure of a glycerol-conducting channel and the basis for its selectivity
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DOI：
10.1126/science.290.5491.481
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发表时间：
2000-10-20
期刊：
影响因子：
56.9
通讯作者：
Stroud, RM
中科院分区：
文献类型：
--
作者：
Fu, DX;Libson, A;Stroud, RM
水通道蛋白家族的膜通道蛋白对特定小分子的渗透具有高度的选择性，对离子和带电溶质具有绝对的排斥作用，并且不会耗散跨细胞膜的电化学势。我们报道了大肠杆菌甘油促进剂(GlpF)的晶体结构，其主要底物甘油的分辨率为2.2埃。甘油分子在两亲性通道中排成一列。在通道的窄选择性过滤器中，甘油烷基主链挤在疏水拐角上，连续的羟基与一对受体原子和给体原子形成氢键。两个保守的天冬氨酸-脯氨酸-丙氨酸基序形成了两个基因复制片段之间的关键界面，每个片段都编码了围绕通道的三个半跨膜螺旋。这种结构阐明了线性碳水化合物选择性渗透的机制，并暗示了离子和水是如何被排除在外的。
Membrane channel proteins of the aquaporin family are highly selective for permeation of specific small molecules, with absolute exclusion of ions and charged solutes and without dissipation of the electrochemical potential across the cell membrane. We report the crystal structure of the Escherichia coli glycerol facilitator (GlpF) with its primary permeant substrate glycerol at 2.2 angstrom resolution. Glycerol molecules line up in an amphipathic channel in single file. In the narrow selectivity filter of the channel the glycerol alkyl backbone is wedged against a hydrophobic corner, and successive hydroxyl groups form hydrogen bonds with a pair of acceptor, and donor atoms. Two conserved aspartic acid-proline-alanine motifs form a key interface between two gene-duplicated segments that each encode three-and-one-half membrane-spanning helices around the channel. This structure elucidates the mechanism of selective permeability for linear carbohydrates and suggests how ions and water are excluded.