STRUCTURAL BASIS FOR SUGAR TRANSLOCATION THROUGH MALTOPORIN CHANNELS AT 3.1-ANGSTROM RESOLUTION
STRUCTURAL BASIS FOR SUGAR TRANSLOCATION THROUGH MALTOPORIN CHANNELS AT 3.1-ANGSTROM RESOLUTION
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DOI：
10.1126/science.7824948
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发表时间：
1995-01-27
期刊：
影响因子：
56.9
通讯作者：
ROSENBUSCH, JP
中科院分区：
文献类型：
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作者：
SCHIRMER, T;KELLER, TA;ROSENBUSCH, JP
三聚麦芽糖孔蛋白（LamB蛋白）促进麦芽糖糊精穿过革兰氏阴性菌的外膜扩散。从大肠杆菌麦芽糖孔蛋白的晶体结构，确定到3.1埃的分辨率，揭示了一个18链，反平行β-桶，形成框架的通道。三个向内折叠的环有助于通过通道的大约一半的收缩。六个偶然的芳香残基排列在通道上，形成从前庭到周质出口的路径。用麦芽三糖浸泡晶体，发现糖与跨越收缩部的疏水轨道结合，这表明麦芽糖和线性寡糖可以通过沿沿着该路径的引导扩散而跨膜移位。
Trimeric maltoporin (LamB protein) facilitates the diffusion of maltodextrins across the outer membrane of Gram-negative bacteria. The crystal structure of maltoporin from Escherichia coli, determined to a resolution of 3.1 angstroms, reveals an 18-stranded, antiparallel beta-barrel that forms the framework of the channel. Three inwardly folded loops contribute to a constriction about halfway through the channel. Six contingent aromatic residues line the channel and form a path from the vestibule to the periplasmic outlet. Soaking of a crystal with maltotriose revealed binding of the sugar to this hydrophobic track across the constriction, which suggests that maltose and linear oligosaccharides may be translocated across the membrane by guided diffusion along this path.