Initial structural and dynamic characterization of the M2 protein transmembrane and amphipathic helices in lipid bilayers
Initial structural and dynamic characterization of the M2 protein transmembrane and amphipathic helices in lipid bilayers
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DOI：
10.1110/ps.03168503
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发表时间：
2003-11-01
期刊：
影响因子：
8
通讯作者：
Cross, TA
中科院分区：
文献类型：
--
作者：
Tian, CL;Gao, PF;Cross, TA
膜蛋白中的两亲性螺旋与脂类双层的疏水/亲水界面相互作用，其结构特征一直难以确定。在这里，甲型流感病毒的全长M2蛋白中的两亲性螺旋的骨架结构和方向已经被表征。用固体核磁共振波谱研究了该蛋白质在凝胶向液晶相转变温度以上的水合DMPC/DMPG脂双层中的结构。在均匀排列的N-15标记和氨基酸特异性标记的M2样品的双层制剂中，观察到了反映螺旋轮的特征PISA(Polar Index Slant Angel)轮。氢/氢交换研究表明，在两亲性螺旋中，一些残基的交换非常缓慢，而跨膜螺旋的交换速度更快。这些后一种结果清楚地表明存在水孔。关于跨膜螺旋轴的交换率的变化为这一说法提供了额外的支持，并表明围绕该四聚体中的螺旋轴发生运动以将整个骨架暴露在孔中。
Amphipathic helices in membrane proteins that interact with the hydrophobic/hydrophilic interface of the lipid bilayer have been difficult to structurally characterize. Here, the backbone structure and orientation of an amphipathic helix in the full-length M2 protein from influenza A virus has been characterized. The protein has been studied in hydrated DMPC/DMPG lipid bilayers above the gel to liquid-crystalline phase transition temperature by solid-state NMR spectroscopy. Characteristic PISA (Polar Index Slant Angle) wheels reflecting helical wheels have been observed in uniformly aligned bilayer preparations of both uniformly N-15 labeled and amino acid specific labeled M2 samples. Hydrogen/deuterium exchange studies have shown the very slow exchange of some residues in the amphipathic helix and more rapid exchange for the transmembrane helix. These latter results clearly suggest the presence of an aqueous pore. A variation in exchange rate about the transmembrane helical axis provides additional support for this claim and suggests that motions occur about the helical axes in this tetramer to expose the entire backbone to the pore.