Folding and Chaperone Interactions of Multi-domain Proteins

项目摘要 将几个功能单位，称为结构域，组合成一个单一的多肽链是一种常见的 创造生物复杂性的进化策略。由此产生的多结构域蛋白质是 普遍存在于所有蛋白质组中，并执行基本的细胞功能。然而，增加的功能 这些大型蛋白质的复杂性使其折叠成天然的功能结构变得复杂。相比之下， 对于许多较小的蛋白质或单个结构域，多结构域蛋白质容易发生错误折叠和 潜在的细胞毒性聚集。在细胞中，有几个因素确保了有效的折叠。折叠开始联合- 翻译过来，虽然核糖体仍在合成多肽。分子伴侣开始 一旦新生的多域蛋白从核糖体中出现，它就会与之相互作用。共同-- 翻译折叠和伴侣相互作用被认为是有效的多结构域的关键 蛋白质折叠。然而，这些过程在分子水平上仍然没有得到很好的定义，因为它 研究它们在技术上具有挑战性。本项目的目标是定义合作翻译的原则 折叠和伴侣的作用更好地理解复杂的多域蛋白如何强健地到达 它们的功能结构。我们正在使用单分子生物物理学和活细胞的组合 为实现这一目标而进行的实验。利用光学镊子，我们正在研究折叠路径 在单分子水平上的新生多结构域蛋白质。对单个分子的操纵是 非常适合于解析新生蛋白质的复杂折叠途径，阐明其作用 核糖体和分子伴侣对折叠过程的影响，并决定如何共翻译 折叠和蛋白质合成是相互耦合和调节的，以确保稳健的结果。这些详细信息请参见 体外研究得到了在活细胞中检测共翻译折叠事件的实验的补充 在多结构域蛋白质中。蛋白质的错误折叠和聚集，蛋白质合成的错误调节和 伴侣功能下降是许多与衰老相关的疾病的特征。我们的研究最终可能 为发现治疗其中一些疾病的新治疗策略提供了机制基础 疾病。

Project Summary Combining several functional units, termed domains, into a single polypeptide chain is a common evolutionary strategy for creating biological complexity. The resulting multi-domain proteins are prevalent in all proteomes and carry out essential cellular functions. However, the increased functional complexity of these large proteins complicates their folding into native functional structures. In contrast to many smaller proteins or individual domains, multi-domain proteins are prone to misfolding and potentially cytotoxic aggregation. In the cell, several factors ensure efficient folding. Folding begins co- translationally, while the ribosome still synthesizes the polypeptide. Molecular chaperones begin to interact with the nascent multi-domain protein as soon as it emerges from the ribosome. Co- translational folding and chaperone interactions are recognized as crucial for efficient multi-domain protein folding. However, these processes remain poorly defined at the molecular level, because it is technically challenging to study them. The goal of this project is to define principles of co-translational folding and chaperone function to better understand how complex multi-domain proteins robustly reach their functional structures. We are using a combination of single-molecule biophysics and live-cell experiments to accomplish this goal. With optical tweezers, we are studying the folding pathways of nascent multi-domain proteins at the single-molecule level. Manipulation of individual molecules is ideally suited to resolve complex folding pathways of nascent proteins, elucidate the contributions of the ribosome and molecular chaperones to the folding process, and determine how co-translational folding and protein synthesis are coupled and regulated to ensure robust outcomes. These detailed in vitro studies are complemented by experiments in live cells that detect co-translational folding events in multi-domain proteins. Protein misfolding and aggregation, misregulation of protein synthesis and decline of chaperone function are hallmarks of many aging-related diseases. Our studies may ultimately provide a mechanistic basis for discovering novel therapeutic strategies to treat some of these diseases.