Conformational changes of colicin Ia channel-forming domain upon membrane binding: a solid-state NMR study
Conformational changes of colicin Ia channel-forming domain upon membrane binding: a solid-state NMR study
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DOI：
10.1016/s0005-2736(02)00340-1
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发表时间：
2002-04-12
影响因子：
3.4
通讯作者：
Hong, M
中科院分区：
文献类型：
--
作者：
Huster, D;Yao, YL;Hong, M
通道形成粘菌素是一种杀菌蛋白，它自发地插入疏水的脂双层中。我们利用幻角旋转固体核磁共振波谱研究了Colicin la通道结构域在水溶态和膜结合态的构象差异，并研究了结合态Colicin对脂质双层结构和动力学的影响。我们检测到两种形式的蛋白质之间的C-13和N-15各向同性化学位移的差异，这表明蛋白质的结构由于膜结合而发生变化。Val Calpha信号由双量子实验明确指定，在膜结合后，各向同性位置的下场位移为0.6ppm，各向异性化学位移跨度减少了4ppm。这些结果表明，膜结合粘附素中的α-螺旋在扩散到膜上时采用了更理想的螺旋扭转角。Colicin结合显著降低了脂链的有序性，表现为H-2四极偶联。这些结果与粘连蛋白La通道结构域在膜-水界面形成扩展的螺旋阵列的模型一致。(C)2002 Elsevier Science B.V.保留所有权利。
Channel-forming colicins are bactericidal proteins that spontaneously insert into hydrophobic lipid bilayers. We have used magic-angle spinning solid-state nuclear magnetic resonance spectroscopy to examine the conformational differences between the water-soluble and the membrane-bound states of colicin la channel domain, and to study the effect of bound colicin on lipid bilayer structure and dynamics. We detected C-13 and N-15 isotropic chemical shift differences between the two forms of the protein, which indicate structural changes of the protein due to membrane binding. The Val Calpha signal, unambiguously assigned by double-quantum experiments, gave a 0.6 ppm downfield shift in the isotropic position and a 4 ppm reduction in the anisotropic chemical shift span after membrane binding. These suggest that the a-helices in the membrane-bound colicin adopt more ideal helical torsion angles as they spread onto the membrane. Colicin binding significantly reduced the lipid chain order, as manifested by H-2 quadrupolar couplings. These results are consistent with the model that colicin la channel domain forms an extended helical array at the membrane-water interface upon membrane binding. (C) 2002 Elsevier Science B.V. All rights reserved.