Pre-aggregation kinetics and intermediates of α-synuclein monitored by the ESIPT probe 7MFE
Pre-aggregation kinetics and intermediates of α-synuclein monitored by the ESIPT probe 7MFE
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DOI：
10.1007/s00249-017-1272-0
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发表时间：
2018-05-01
影响因子：
2
通讯作者：
Jovin, Thomas M.
中科院分区：
文献类型：
--
作者：
Fauerbach, Jonathan A.;Jovin, Thomas M.
淀粉样蛋白疾病广泛家族的定义特征是形成缠结的细长蛋白原纤维和表现出交叉β折叠二级结构的无定形聚集体的网络。淀粉样蛋白转化的时间过程已在体外与帕金森病（α-突触核蛋白）、阿尔茨海默病（Tau）和亨廷顿病（Huntingtin）神经退行性病理学相关的蛋白质进行了广泛研究。尽管人们对从可溶的、本质上无序的单体到纤维状最终状态的转变的热力学和动力学了解很多，但目前被认为是细胞毒性的主要引发剂的假定的低聚中间体仍然知之甚少。我们通过使用 ESIPT（激发态分子内蛋白转移）探针监测 AS 聚集来检测和表征淀粉样蛋白前体，其中介绍了其中一种 7MFE [7-(3-马来酰亚胺基-N-丙酰胺)-2-(4-二乙氨基苯基)-3-羟基色酮]，并与之前使用的相关化合物 6MFC 进行了比较。在聚集过程中获得了一系列 140 个稀疏标记 AS 的光谱，并将其解析为离散分子种类（包括单体、纤维状和中间形式的集合体）的相对贡献（光谱、强度）。基于这些发现，设计了一种动力学方案来模拟作为关键参数函数的进度曲线。该模型的一个基本特征（之前在淀粉样蛋白聚集方案中未曾提及）是，当 AS 暴露于 >= 37 A 摄氏度时，通过单体缩合自发产生的离散胶体纳米粒子对分子模糊性的催化。
The defining feature of the extensive family of amyloid diseases is the formation of networks of entangled elongated protein fibrils and amorphous aggregates exhibiting crossed beta-sheet secondary structure. The time course of amyloid conversion has been studied extensively in vitro with the proteins involved in the neurodegenerative pathology of Parkinson's disease (alpha-synuclein), Alzheimer's disease (Tau) and Huntington's disease (Huntingtin). Although much is known about the thermodynamics and kinetics of the transition from a soluble, intrinsically disordered monomer to the fibrillar end state, the putative oligomeric intermediates, currently considered to be the major initiators of cellular toxicity, are as yet poorly defined. We have detected and characterized amyloid precursors by monitoring AS aggregation with ESIPT (excited state intramolecular protein transfer) probes, one of which, 7MFE [7-(3-maleimido-N-propanamide)-2-(4-diethyaminophenyl)-3-hydroxychromone], is introduced here and compared with a related compound, 6MFC, used previously. A series of 140 spectra for sparsely labeled AS was acquired during the course of aggregation, and resolved into the relative contributions (spectra, intensities) of discrete molecular species including the monomeric, fibrillar, and ensemble of intermediate forms. Based on these findings, a kinetic scheme was devised to simulate progress curves as a function of key parameters. An essential feature of the model, one not previously invoked in schemes of amyloid aggregation, is the catalysis of molecular fuzziness by discrete colloidal nanoparticles arising spontaneously via monomer condensation upon exposure of AS to >= 37 A degrees C.