Systematic analysis of
Systematic analysis of
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通讯作者：
Wei-Feng Xue;S. Homans;S. Radford
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作者：
Wei-Feng Xue;S. Homans;S. Radford
错误折叠的蛋白质自组装成有序的纤维聚集体，被称为淀粉样蛋白，导致许多人类疾病。尽管越来越多的蛋白质和肽片段被识别为淀粉样蛋白，但这些淀粉样蛋白聚集体如何聚集仍不清楚。特别是，成核物种的身份，一个短暂的实体，定义纤维的形成速度，仍然是一个关键的悬而未决的问题。在此，我们提出了一种分析淀粉样蛋白原纤维自组装的新策略，包括对大量反应过程曲线的全局分析，以及随后对大量可能的组装机制进行系统测试和排序。利用这种方法，我们已经表征了（cid:1） 2 -微球蛋白（(cid:1) 2 m）淀粉样原纤维的核依赖性形成机制。我们表明，通过在结构和热力学方面定义成核，涉及结构核尺寸的模型大约六聚体的大小与纤维形成速率相对较小的浓度依赖性是一致的，这与基于更简单的成核组装理论的期望相反。研究结果表明，纤维断裂是主要的次级过程，在纤维形成过程中产生比单凭成核组装理论预测的更高的明显协同性。所开发的模型能够解释和预测（cid:1） 2 m纤维形成的行为，并为解释在其他淀粉样蛋白系统中观察到的一般特性提供了基本原理，例如纤维生长加速和搅拌下的通路转移。
Self-assembly of misfolded proteins into ordered fibrillar aggregates known as amyloid results in numerous human diseases. Despite an increasing number of proteins and peptide fragments beingrecognisedasamyloidogenic,howtheseamyloidaggregates assemble remains unclear. In particular, the identity of the nucleating species, an ephemeral entity that defines the rate of fibril formation, remains a key outstanding question. Here, we propose a new strategy for analyzing the self-assembly of amyloid fibrils involving global analysis of a large number of reaction progress curves and the subsequent systematic testing and ranking of a large number of possible assembly mechanisms. Using this approach, we have characterized the mechanism of the nucleation-dependentformationof (cid:1) 2 -microglobulin( (cid:1) 2 m)amyloidfibrils.We show, by defining nucleation in the context of both structural and thermodynamic aspects, that a model involving a structural nucleus size approximately the size of a hexamer is consistent with the relatively small concentration dependence of the rate of fibril formation, contrary to expectations based on simpler theories of nucleatedassembly.Wealsodemonstratethatfibrilfragmentation is the dominant secondary process that produces higher apparent cooperatively in fibril formation than predicted by nucleated assembly theories alone. The model developed is able to explain and predict the behavior of (cid:1) 2 m fibril formation and provides a rationale for explaining generic properties observed in other amyloid systems, such as fibril growth acceleration and pathway shifts under agitation.