Effects of Curvature and Composition on α-Synuclein Binding to Lipid Vesicles
Effects of Curvature and Composition on α-Synuclein Binding to Lipid Vesicles
复制标题
DOI：
10.1016/j.bpj.2010.07.056
复制
发表时间：
2010-10-06
影响因子：
3.4
通讯作者：
Rhoades, Elizabeth
中科院分区：
文献类型：
--
作者：
Middleton, Elizabeth R.;Rhoades, Elizabeth
帕金森病的特征在于存在主要由神经元蛋白α-突触核蛋白（α S）组成的细胞内聚集体。人们认为α S与各种细胞膜之间的相互作用对其天然功能很重要，并且与其在疾病中的作用相关。我们使用荧光相关光谱研究结合的α S的脂质囊泡作为一个功能的脂质成分和膜曲率。我们确定这些参数如何影响α S的摩尔分配系数，提供结合能的定量测量，并计算结合单个蛋白质所需的脂质的数量。特定的阴离子脂质对结合自由能有很大的影响。脂质链饱和度的影响结合相互作用在较小的程度上，与较大的分配系数测量的凝胶相囊泡比流体相囊泡，即使在阴离子脂质成分的情况下。虽然我们观察到变异的突变体蛋白质的结合，分区的自由能的差异是不太戏剧性的比不同的脂质组合物。囊泡曲率对结合亲和力有很强的影响，与大单层囊泡相比，小单层囊泡的亲和力增加>15倍，表明α S可能是曲率敏感蛋白。我们的研究结果提供了深入了解如何膜的物理特性可以调节与细胞膜的相互作用的α S。
Parkinson's disease is characterized by the presence of intracellular aggregates composed primarily of the neuronal protein alpha-synuclein (alpha S). Interactions between alpha S and various cellular membranes are thought to be important to its native function as well as relevant to its role in disease. We use fluorescence correlation spectroscopy to investigate binding of alpha S to lipid vesicles as a function of the lipid composition and membrane curvature. We determine how these parameters affect the molar partition coefficient of alpha S, providing a quantitative measure of the binding energy, and calculate the number of lipids required to bind a single protein. Specific anionic lipids have a large effect on the free energy of binding. Lipid chain saturation influences the binding interaction to a lesser extent, with larger partition coefficients measured for gel-phase vesicles than for fluid-phase vesicles, even in the absence of anionic lipid components. Although we observe variability in the binding of the mutant proteins, differences in the free energies of partitioning are less dramatic than with varied lipid compositions. Vesicle curvature has a strong effect on the binding affinity, with a >15-fold increase in affinity for small unilamellar vesicles over large unilamellar vesicles, suggesting that alpha S may be a curvature-sensing protein. Our findings provide insight into how physical properties of the membrane may modulate interactions of alpha S with cellular membranes.