Transmembrane four-helix bundle of influenza A M2 protein channel: Structural implications from helix tilt and orientation
Transmembrane four-helix bundle of influenza A M2 protein channel: Structural implications from helix tilt and orientation
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DOI：
10.1016/s0006-3495(97)78279-1
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发表时间：
1997-11-01
影响因子：
3.4
通讯作者：
Cross, TA
中科院分区：
文献类型：
--
作者：
Kovacs, FA;Cross, TA
在水合二肉豆蔻酰磷脂酰胆碱脂质双层中，用固态核磁共振研究了甲型流感病毒M2蛋白的跨膜部分。从同位素标记的肽样品中获得定向约束，这些样品机械地排列在薄玻璃板之间。N-15从单位点标记样品的化学位移约束了相对于磁场的分子框架。当这些约束被应用到肽，作为一个均匀的α -螺旋模型，螺旋的倾斜相对于双层法线被确定为33度+/- 3度。此外，螺旋轴的方向也在+/-30度的误差范围内确定。这些结果表明，这种四聚体蛋白的包装是在一个左旋的四螺旋束。只有在如此大的倾斜角度下，亲水残基才会与通道轴对齐。
The transmembrane portion of the M2 protein from the Influenza A virus has been studied in hydrated dimyristroylphosphotidylcholine lipid bilayers with solid-state NMR. Orientational constraints were obtained from isotopically labeled peptide samples mechanically aligned between thin glass plates. N-15 chemical shifts from single site labeled samples constrain the molecular frame with respect to the magnetic field. When these constraints are applied to the peptide, modeled as a uniform alpha-helix, the tilt of the helix with respect to the bilayer normal was determined to be 33 degrees +/- 3 degrees. Furthermore, the orientation about the helix axis was also determined within an error of +/-30 degrees. These results imply that the packing of this tetrameric protein is in a left-handed four-helix bundle. Only with such a large tilt angle are the hydrophilic residues aligned to the channel axis.