Mechanisms of the eukaryotic chaperonin TRiC/CCT and its cochaperone Prefoldin

描述（由申请人提供）：许多蛋白质依赖于分子伴侣正确折叠。不能正确折叠与许多疾病相关，包括癌症和与衰老相关的神经退行性疾病。虽然大多数伴侣蛋白在功能上是冗余的，但TRiC及其同源伴侣蛋白在所有界中都是必需的。所有真核生物的伴侣蛋白都由两个背靠背堆叠的环组成，每个环由7-9个亚基形成，这些亚基产生一个包裹底物的中心空腔。TRiC介导的折叠由ATP结合和水解驱动，这调节其构象循环。虽然在理解更简单的同源寡聚古细菌伴侣蛋白的机制方面取得了进展，但由八个旁系同源亚基组成的真核伴侣蛋白TRiC的折叠机制仍然难以捉摸。重要的是，亚基的差异提供了独特的折叠特性，允许TRiC折叠同源伴侣蛋白不能折叠的必需真核底物。TRiC也由异源六聚体辅伴侣蛋白前折叠蛋白辅助，其被认为将非天然折叠的底物转移至TRiC。本提案的目标是研究TRiC的ATP依赖性构象周期的机制，功能和结构方面以及TRiC底物识别的机制;我还旨在定义这些TRiC功能是否以及如何被Prefoldin调制。Frydman实验室在酵母中开发了一种系统，可以用含有致死突变的相同亚基替换任何TRiC亚基，并且拥有丰富的经验和工具来解决体内和体外这些问题。

DESCRIPTION (provided by applicant): Many proteins are dependent upon chaperones to properly fold. Failure to fold correctly is associated with many diseases including cancer and aging associated neurodegenerative disorders. While most chaperones are redundant in function, TRiC and its homologous chaperonins are essential in all kingdoms. All eukaryotic chaperonins are composed of two rings stacked back to back, each formed by 7-9 subunits that produce a central cavity that encapsulates substrates. TRiC-mediated folding is driven by ATP binding and hydrolysis, which regulate its conformational cycle. While progress has been made in understanding the mechanism of simpler homo-oligomeric archaeal chaperonins, the mechanism of folding by the eukaryotic chaperonin, TRiC, which is composed of eight paralogous subunits, has remained elusive. Importantly, the divergence of the subunits has provided unique folding properties allowing TRiC to fold essential eukaryotic substrates that the homologous chaperonins are incapable of folding. TRiC is also assisted by the hetero-hexameric cochaperone Prefoldin, which is thought to transfer non-natively folded substrates to TRiC. The goal of this proposal is to study mechanistic, functional and structural aspects of the ATP-dependent conformational cycle of TRiC and the mechanisms of TRiC substrate-recognition; I also aim to define whether and how these TRiC functions are modulated by Prefoldin. The Frydman lab has developed a system in yeast that allows replacement of any of the TRiC subunits with the same subunit containing lethal mutations, and has extensive experience and tools to address these questions in vivo and in vitro.