Structure and dynamics of the extended-helix state of alpha-synuclein: Intrinsic lability of the linker region.
Structure and dynamics of the extended-helix state of alpha-synuclein: Intrinsic lability of the linker region.
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α-突触核蛋白延伸螺旋状态的结构和动力学：连接子区域的内在不稳定性。
DOI：
10.1002/pro.3426
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Eliezer,David
中科院分区：
文献类型：
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作者：
Sung,Yoon-Hui;Eliezer,David
帕金森氏蛋白α-突触核蛋白在体内与突触囊泡结合，并在体外与脂质囊泡结合时采用高度延伸的螺旋构象。结合到小脂质或洗涤剂胶束的α-突触核蛋白的高分辨率结构分析揭示了由非螺旋接头连接的两个螺旋，但囊泡结合的延伸螺旋状态的相应研究受到蛋白质囊泡复合物的大小和异质性的阻碍。在这里，我们使用氟化醇（FA）诱导溶液中α-突触核蛋白的高度螺旋聚集抗性状态，其类似于囊泡结合的延伸螺旋状态，但易于使用高分辨率溶液状态NMR进行表征。化学位移、NOE、耦合常数、PRE和弛豫测量的分析表明，FA溶液中α-突触核蛋白的脂质结合结构域确实采用了单个连续螺旋，并且该螺旋的末端彼此之间没有可检测到的接近。螺旋在中心是有序的，但其特征是快速内部运动的增加，这表明螺旋在接近末端时磨损。螺旋的中心区域表现出较慢的时间尺度运动，这可能是由于高度各向异性结构的弯曲。重要的是，在与胶束结合的α-突触核蛋白的非螺旋接头对应的区域中，短距离和中距离NOE弱或缺失，表明蛋白质该区域的螺旋结构本质上是不稳定的。这表明α-突触核蛋白从延伸螺旋到断裂螺旋状态的转化代表了功能相关的结构转变。
The Parkinson's protein alpha‐synuclein binds to synaptic vesicles in vivo and adopts a highly extended helical conformation when binding to lipid vesicles in vitro. High‐resolution structural analysis of alpha‐synuclein bound to small lipid or detergent micelles revealed two helices connected by a non‐helical linker, but corresponding studies of the vesicle‐bound extended‐helix state are hampered by the size and heterogeneity of the protein‐vesicle complex. Here we employ fluorinated alcohols (FAs) to induce a highly helical aggregation‐resistant state of alpha‐synuclein in solution that resembles the vesicle‐bound extended‐helix state but is amenable to characterization using high‐resolution solution‐state NMR. Analysis of chemical shift, NOE, coupling constant, PRE and relaxation measurements shows that the lipid‐binding domain of alpha‐synuclein in FA solutions indeed adopts a single continuous helix and that the ends of this helix do not come into detectable proximity to each other. The helix is well ordered in the center, but features an increase in fast internal motions suggestive of helix fraying approaching the termini. The central region of the helix exhibits slower time scale motions that likely result from flexing of the highly anisotropic structure. Importantly, weak or missing short‐ and intermediate‐range NOEs in the region corresponding to the non‐helical linker of micelle‐bound alpha‐synuclein indicate that the helical structure in this region of the protein is intrinsically unstable. This suggests that conversion of alpha‐synuclein from the extended‐helix to the broken‐helix state represents a functionally relevant structural transition.