Structural and functional implications of C-terminal regions of α-synuclein
Structural and functional implications of C-terminal regions of α-synuclein
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DOI：
10.1021/bi026284c
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发表时间：
2002-11-19
期刊：
影响因子：
2.9
通讯作者：
Yang, CH
中科院分区：
文献类型：
--
作者：
Kim, TD;Paik, SR;Yang, CH
α-突触核蛋白的聚集被认为在帕金森病（PD）的发病机制中起主要作用，帕金森病的特征在于脑中存在胞浆内路易体（LB）。α-突触核蛋白及其缺失突变体在很大程度上是未折叠的蛋白质，具有无规卷曲结构，如CD光谱、荧光光谱、凝胶过滤色谱和超离心所揭示的。基于α-突触核蛋白的高度未折叠和柔性构象，我们研究了其在体外的分子伴侣样活性。在我们的实验中，α-突触核蛋白抑制模型底物的聚集，并在热应激期间保护醇脱氢酶和罗丹酸酶的催化活性。此外，α-突触核蛋白抑制还原/变性溶菌酶的复性途径上的初始聚集。有趣的是，删除的C-末端区域导致废除的伴侣活性，虽然在很大程度上保持非结构化的构象。此外，α-synuclein在热应激过程中能抑制大肠杆菌细胞内多种蛋白的聚集，而C端缺失突变体不能对这些蛋白提供任何保护。合成C-末端肽和C-末端缺失突变体的结果表明，第二个酸性重复序列（125）YEMPSEEGYQDYEPEA（140）对α-突触核蛋白的伴侣活性很重要，C-末端缺失导致促进聚集，同时消除伴侣活性。
Aggregation of alpha-synuclein is thought to play a major role in the pathogenesis of Parkinson's disease (PD), which is characterized by the presence of intracytoplasmic Lewy bodies (LB) in the brain. a-Synuclein and its deletion mutants are largely unfolded proteins with random coil structures as revealed by CD spectra, fluorescence spectra, gel filtration chromatography, and ultracentrifugation. On the basis of its highly unfolded and flexible conformation, we have investigated the chaperone-like activity of alpha-synuclein in vitro. In our experiments, alpha-synuclein inhibited the aggregation of model substrates and protected the catalytic activity of alcohol dehydrogenase and rhodanese during heat stress. In addition, alpha-synuclein inhibited the initial aggregation of reduced/denatured lysozyme on the refolding pathway. Interestingly, deletion of the C-terminal regions led to the abolishment of chaperone activity, although largely unstructured conformations are maintained. Moreover, alpha-synuclein could inhibit the aggregation of various Escherichia coli cellular proteins during heat stress, and C-terminal deletion mutants could not provide any protection to these cellular proteins. Results with synthetic C-terminal peptides and C-terminal deletion mutants suggest that the second acidic repeat, (125)YEMPSEEGYQDYEPEA(140), is important for the chaperone activity of alpha-synuclein, and C-terminal deletion leads to the facilitated aggregation with the elimination of chaperone activity.