Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA.
Proc Natl Acad Sci U S A. 2012 Feb 14;109(7):2336-41. doi: 10.1073/pnas.1109526109. Epub 2012 Jan 27.
We hypothesize that the first step of aggregation of disordered proteins, such as α-synuclein, is controlled by the rate of backbone reconfiguration. When reconfiguration is fast, bimolecular association is not stable, but as reconfiguration slows, association is more stable and subsequent aggregation is faster. To investigate this hypothesis, we have measured the rate of intramolecular diffusion in α-synuclein, a protein involved in Parkinson's disease, under solvent conditions that accelerate or decelerate aggregation. Using the method of tryptophan-cysteine (Trp-Cys) quenching, the rate of intramolecular contact is measured in four different loops along the chain length. This intrinsically disordered protein is highly diffusive at low temperature at neutral pH, when aggregation is slow, and compacts and diffuses more slowly at high temperature or low pH, when aggregation is rapid. Diffusion also slows with the disease mutation A30P. This work provides unique insights into the earliest steps of α-synuclein aggregation pathway and should provide the basis for the development of drugs that can prevent aggregation at the initial stage.
我们假设无序蛋白质（如α-突触核蛋白）聚集的第一步受到骨架重排速率的控制。当重排速度较快时，双分子缔合不稳定，但当重排速度减慢时，缔合更稳定，随后的聚集速度也更快。为了验证这一假设，我们在加速或减缓聚集的溶剂条件下，测量了与帕金森病相关的蛋白质α-突触核蛋白的分子内扩散速率。我们使用色氨酸-半胱氨酸（Trp-Cys）猝灭法，在链长的四个不同环上测量分子内接触的速率。在中性 pH 值的低温下，当聚集缓慢时，这种高度无序的蛋白质具有很高的扩散性，而在高温或低 pH 值下，当聚集迅速时，它会变得更加紧凑，扩散速度也更慢。在疾病突变 A30P 中，扩散也会减慢。这项工作为α-突触核蛋白聚集途径的最初步骤提供了独特的见解，应该为开发能够在初始阶段预防聚集的药物提供基础。
