Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Am Chem Soc. 2011 Sep 14;133(36):14184-7. doi: 10.1021/ja2045309. Epub 2011 Aug 22.
Biological membranes present a highly fluid environment, and integration of proteins within such membranes is itself highly dynamic: proteins diffuse laterally within the plane of the membrane and rotationally about the normal vector of this plane. We demonstrate that whole-body motions of proteins within a lipid bilayer can be determined from NMR (15)N relaxation rates collected for different-sized bicelles. The importance of membrane integration and interaction is particularly acute for proteins and peptides that function on the membrane itself, as is the case for pore-forming and fusion-inducing proteins. For the influenza hemagglutinin fusion peptide, which lies on the surface of membranes and catalyzes the fusion of membranes and vesicles, we found large-amplitude, rigid-body wobbling motions on the nanosecond time scale relative to the lipid bilayer. This behavior complements prior analyses where data were commonly interpreted in terms of a static oblique angle of insertion for the fusion peptide with respect to the membrane. Quantitative disentanglement of the relative motions of two interacting objects by systematic variation of the size of one is applicable to a wide range of systems beyond protein-membrane interactions.
生物膜呈现出高度流动的环境，而蛋白质在这种膜中的整合本身就是高度动态的：蛋白质在膜的平面内横向扩散，并围绕该平面的法向量旋转。我们证明，通过为不同大小的双分子层收集的 NMR（15）N 弛豫率，可以确定脂质双层中蛋白质的整体运动。对于在膜本身起作用的蛋白质和肽，膜的整合和相互作用非常重要，对于形成孔和诱导融合的蛋白质也是如此。对于流感血凝素融合肽，它位于膜的表面并催化膜和囊泡的融合，我们发现相对于脂质双层，它在纳秒时间尺度上具有大振幅的刚体摆动运动。这种行为补充了先前的分析，其中数据通常根据融合肽相对于膜的静态倾斜插入角度进行解释。通过系统地改变一个相互作用物体的大小来定量解开两个相互作用物体的相对运动，适用于蛋白质-膜相互作用之外的广泛系统。
