Spin-Label EPR on α-Synuclein Reveals Differences in the Membrane Binding Affinity of the Two Antiparallel Helices
Spin-Label EPR on α-Synuclein Reveals Differences in the Membrane Binding Affinity of the Two Antiparallel Helices
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DOI：
10.1002/cbic.200800238
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发表时间：
2008-10-13
期刊：
影响因子：
3.2
通讯作者：
Huber, Martina
中科院分区：
文献类型：
--
作者：
Drescher, Malte;Godschalk, Frans;Huber, Martina
帕金森病相关蛋白α-突触核蛋白（α S）的推定功能被认为涉及膜结合。因此，α S与由两性离子（POPC）和阴离子（POPG）脂质组成的膜的相互作用通过附着于蛋白质的自旋标记的迁移率来研究。产生了α S的经标记的变体，其在位置9、18（均为螺旋1）、69、90（均为螺旋2）和140（C末端）处含有自旋标记。蛋白质结合POPC/POPG囊泡，但α S140导致两个流动性组件的相关时间为0.5和3纳秒，POPG摩尔分数>0.4。监测这些组分作为POPG摩尔分数的函数，揭示了在低负电荷密度下，螺旋1比螺旋2更紧密地结合，这表明α S的部分结合形式。因此，α S与低电荷密度膜的相互作用可能在螺旋处开始。由此获得的局部结合信息给出了α S对膜的亲和力的更有区别的图片。这些发现有助于我们了解α S-膜相互作用的细节和结构后果。
The putative function of the Parkinson's disease-related protein alpha-Synuclein (alpha S) is thought to involve membrane binding. Therefore, the interaction of alpha S with membranes composed of zwitter ionic (POPC) and anionic (POPG) lipids was investigated through the mobility of spin labels attached to the protein. Differently labelled variants of alpha S were produced, containing a spin label at positions 9, 18 (both helix 1), 69, 90 (both helix 2), and 140 (C terminus). Protein binding to POPC/POPG vesicles for all but alpha S140 resulted in two mobility components with correlation times of 0.5 and 3 ns, for POPG mole fractions >0.4. Monitoring these components as a function of the POPG mole fraction revealed that at low negative charge densities helix 1 is more tightly bound than helix 2, this indicates a partly bound form of alpha S. Thus, the interaction of alpha S with membranes of low charge densities might be initiated at helix). The local binding information thus obtained gives a more differentiated picture of the affinity of alpha S to membranes. These findings contribute to our understanding of the details and structural consequences of alpha S-membrane interactions.