Effects of amantadine on the dynamics of membrane-bound influenza A M2 transmembrane peptide studied by NMR relaxation.
Effects of amantadine on the dynamics of membrane-bound influenza A M2 transmembrane peptide studied by NMR relaxation.
复制标题
DOI：
10.1007/s10858-009-9352-9
复制
发表时间：
2009-09
影响因子：
2.7
通讯作者：
Hong M
中科院分区：
文献类型：
--
作者：
Cady SD;Hong M
液晶脂质双层中膜蛋白的分子运动处于各向同性液体和固体运动之间的界面。具体而言，膜蛋白能够在微秒时间尺度上进行整体单轴扩散。在这项工作中，我们研究了由甲型流感M2跨膜肽（M2TMP）的单轴扩散所导致的1H旋转坐标系自旋 - 晶格弛豫（T1ρ），该肽在脂质双层中形成一个四聚体质子通道。这种单轴扩散之前已通过M2TMP在二棕榈酰磷脂酰胆碱（DLPC）双层中的2H、15N和13C核磁共振谱线形状得到证明。当与一种抑制剂金刚烷胺结合时，该蛋白质在生理温度下展现出明显更窄的谱线宽度。我们现在通过在有和没有金刚烷胺存在的情况下，温度相关的1H T1ρ弛豫时间来研究这种谱线变窄的原因。对温度依赖性的分析表明，在313 K时，金刚烷胺将运动的相关时间从无配体肽的2.8±0.9微秒降低到结合肽的0.89±0.41微秒。因此，结合肽的谱线变窄是由于更好地避开了核磁共振时间尺度以及对中间时间尺度展宽的抑制。结合肽更快的扩散是由于更高的运动尝试频率，这表明金刚烷胺形成了更紧密堆积且更具内聚力的螺旋束。对[相关参数]温度依赖性的分析表明，运动的活化能从无配体肽的14.0±4.0 kJ/mol增加到结合肽的23.3±6.2 kJ/mol。这种更高的活化能表明脂质双层中蛋白质通道外多余的金刚烷胺增加了膜的黏度。因此，与蛋白质结合的金刚烷胺加速了螺旋束的扩散，而双层中多余的金刚烷胺增加了膜的黏度。
The molecular motions of membrane proteins in liquid-crystalline lipid bilayers lie at the interface between motions in isotropic liquids and in solids. Specifically, membrane proteins can undergo whole-body uniaxial diffusion on the microsecond time scale. In this work, we investigate the 1H rotating-frame spin-lattice relaxation (T1ρ) caused by the uniaxial diffusion of the influenza A M2 transmembrane peptide (M2TMP), which forms a tetrameric proton channel in lipid bilayers. This uniaxial diffusion was proved before by 2H, 15N and 13C NMR lineshapes of M2TMP in DLPC bilayers. When bound to an inhibitor, amantadine, the protein exhibits significantly narrower linewidths at physiological temperature. We now investigate the origin of this line narrowing through temperature-dependent 1H T1ρ relaxation times in the absence and presence of amantadine. Analysis of the temperature dependence indicates that amantadine decreases the correlation time of motion from 2.8 ± 0.9 μs for the apo peptide to 0.89 ± 0.41 μs for the bound peptide at 313 K. Thus the line narrowing of the bound peptide is due to better avoidance of the NMR time scale and suppression of intermediate time scale broadening. The faster diffusion of the bound peptide is due to the higher attempt rate of motion, suggesting that amantadine creates better-packed and more cohesive helical bundles. Analysis of the temperature dependence of indicates that the activation energy of motion increased from 14.0 ± 4.0 kJ/mol for the apo peptide to 23.3 ± 6.2 kJ/mol for the bound peptide. This higher activation energy indicates that excess amantadine outside the protein channel in the lipid bilayer increases the membrane viscosity. Thus, the protein-bound amantadine speeds up the diffusion of the helical bundles while the excess amantadine in the bilayer increases the membrane viscosity.