Relationship between prion propensity and the rates of individual molecular steps of fibril assembly.
Relationship between prion propensity and the rates of individual molecular steps of fibril assembly.
复制标题
DOI：
10.1074/jbc.m110.208934
复制
发表时间：
2011-04-08
期刊：
影响因子：
--
通讯作者：
Perrett S
中科院分区：
文献类型：
--
作者：
Wang YQ;Buell AK;Wang XY;Welland ME;Dobson CM;Knowles TP;Perrett S
多肽和蛋白质具有自组装成被称为淀粉样纤维的普通纤维纳米结构的固有倾向，其中一些与阿尔茨海默病等医学疾病有关。在某些情况下，这种结构可以在生命系统中作为普恩病毒自我繁殖，并将特征特征传递给宿主有机体。允许某些淀粉样蛋白而不是其他淀粉样蛋白作为普恩蛋白发挥作用的机制尚不完全清楚。由于该系统在实验上被证明是高度可控的，因此通过对酵母中的普恩现象的研究已经在理解普恩现象方面取得了很大进展；但对组装过程的生物物理和动力学的定量理解仍然具有挑战性。在这里，我们探索了来自酿酒酵母和矛盾酵母的Ure2p蛋白的两个密切相关的同源物的组装，并通过使用动力学理论与溶液和生物传感器分析相结合，我们能够比较Pron原纤维组装的单个微观步骤的速率。我们发现，对于这些蛋白质，碎片率是在种子原纤维的结构中编码的，而伸长率主要由可溶性前体蛋白的性质决定。我们的结果进一步表明，伸长速度较快但断裂频率较低的纤维可能会失去作为普恩病毒传播的能力。这些发现阐明了蛋白质的体外聚集和体内Pron增殖之间的联系，并为定量理解正常和异常生物途径中控制淀粉样蛋白纤维行为的参数提供了一个框架。
Peptides and proteins possess an inherent propensity to self-assemble into generic fibrillar nanostructures known as amyloid fibrils, some of which are involved in medical conditions such as Alzheimer disease. In certain cases, such structures can self-propagate in living systems as prions and transmit characteristic traits to the host organism. The mechanisms that allow certain amyloid species but not others to function as prions are not fully understood. Much progress in understanding the prion phenomenon has been achieved through the study of prions in yeast as this system has proved to be experimentally highly tractable; but quantitative understanding of the biophysics and kinetics of the assembly process has remained challenging. Here, we explore the assembly of two closely related homologues of the Ure2p protein from Saccharomyces cerevisiae and Saccharomyces paradoxus, and by using a combination of kinetic theory with solution and biosensor assays, we are able to compare the rates of the individual microscopic steps of prion fibril assembly. We find that for these proteins the fragmentation rate is encoded in the structure of the seed fibrils, whereas the elongation rate is principally determined by the nature of the soluble precursor protein. Our results further reveal that fibrils that elongate faster but fracture less frequently can lose their ability to propagate as prions. These findings illuminate the connections between the in vitro aggregation of proteins and the in vivo proliferation of prions, and provide a framework for the quantitative understanding of the parameters governing the behavior of amyloid fibrils in normal and aberrant biological pathways.