Genomics Research Center, Academia Sinica, Taipei, Taiwan.
PLoS One. 2013;8(1):e53487. doi: 10.1371/journal.pone.0053487. Epub 2013 Jan 22.
Amyloid fibrils of α-synuclein are the main constituent of Lewy bodies deposited in substantial nigra of Parkinson's disease brains. α-Synuclein is an intrinsically disordered protein lacking compact secondary and tertiary structures. To enhance the understanding of its structure and function relationship, we utilized temperature treatment to study α-synuclein conformational changes and the subsequent effects. We found that after 1 hr of high temperature pretreatment, >80°C, α-synuclein fibrillization was significantly inhibited. However, the temperature melting coupled with circular dichroism spectra showed that α-synuclein was fully reversible and the NMR studies showed no observable structural changes of α-synuclein after 95°C treatment. By using cross-linking and analytical ultracentrifugation, rare amount of pre-existing α-synuclein oligomers were found to decrease after the high temperature treatment. In addition, a small portion of C-terminal truncation of α-synuclein also occurred. The reduction of pre-existing oligomers of α-synuclein may contribute to less seeding effect that retards the kinetics of amyloid fibrillization. Overall, our results showed that the pre-existing oligomeric species is a key factor contributing to α-synuclein fibrillization. Our results facilitate the understanding of α-synuclein fibrillization.
α-突触核蛋白的淀粉样纤维是帕金森病大脑黑质中Lewy 体的主要成分。α-突触核蛋白是一种无规则卷曲的蛋白质，缺乏紧凑的二级和三级结构。为了增强对其结构和功能关系的理解，我们利用温度处理来研究 α-突触核蛋白构象变化及其后续影响。我们发现，在 80°C 以上的高温预处理 1 小时后，α-突触核蛋白的纤维化显著受到抑制。然而，温度熔融与圆二色性光谱表明，α-突触核蛋白是完全可逆的，并且在 95°C 处理后，NMR 研究没有观察到 α-突触核蛋白的结构变化。通过使用交联和分析超速离心，发现高温处理后，少量预先存在的α-突触核蛋白寡聚物减少。此外，α-突触核蛋白的 C 端截断也发生了一小部分。α-突触核蛋白预先存在的寡聚物的减少可能导致较少的种子效应，从而减缓淀粉样纤维的动力学。总的来说，我们的结果表明，预先存在的寡聚体是促进α-突触核蛋白纤维化的关键因素。我们的结果有助于理解α-突触核蛋白的纤维化。
