Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge CB2 1EW, UK.
Department of Chemistry, Federal University of São Carlos, São Carlos, 13565-905 São Paulo, Brazil.
Proc Natl Acad Sci U S A. 2023 Feb 28;120(9):e2208792120. doi: 10.1073/pnas.2208792120. Epub 2023 Feb 21.
The aggregation of α-synuclein into amyloid fibrils has been under scrutiny in recent years because of its association with Parkinson's disease. This process can be triggered by a lipid-dependent nucleation process, and the resulting aggregates can proliferate through secondary nucleation under acidic pH conditions. It has also been recently reported that the aggregation of α-synuclein may follow an alternative pathway, which takes place within dense liquid condensates formed through phase separation. The microscopic mechanism of this process, however, remains to be clarified. Here, we used fluorescence-based assays to enable a kinetic analysis of the microscopic steps underlying the aggregation process of α-synuclein within liquid condensates. Our analysis shows that at pH 7.4, this process starts with spontaneous primary nucleation followed by rapid aggregate-dependent proliferation. Our results thus reveal the microscopic mechanism of α-synuclein aggregation within condensates through the accurate quantification of the kinetic rate constants for the appearance and proliferation of α-synuclein aggregates at physiological pH.
近年来，由于与帕金森病有关，α-突触核蛋白聚集成淀粉样纤维一直受到关注。这个过程可以被脂依赖性成核过程触发，而由此产生的聚集体可以在酸性 pH 条件下通过二次成核进行增殖。最近也有报道称，α-突触核蛋白的聚集可能遵循另一种途径，这种途径发生在通过相分离形成的密集液相凝聚物内。然而，这个过程的微观机制仍有待阐明。在这里，我们使用基于荧光的测定法，使我们能够对α-突触核蛋白在液相凝聚物中聚集过程的微观步骤进行动力学分析。我们的分析表明，在 pH 7.4 时，该过程首先是自发的初级成核，然后是快速的、依赖于聚集体的增殖。因此，我们的结果通过准确量化生理 pH 下α-突触核蛋白聚集体出现和增殖的动力学速率常数，揭示了α-突触核蛋白在凝聚物中聚集的微观机制。
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