Folding and Chaperone Interactions of Multi-domain Proteins

项目摘要 将几个功能单元（称为结构域）组合成单个多肽链是常见的方法。 创造生物复杂性的进化策略。得到的多结构域蛋白是 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 这些大蛋白质的复杂性使它们折叠成天然功能结构变得复杂。相比之下 对于许多较小的蛋白质或单个结构域，多结构域蛋白质易于错误折叠， 潜在的细胞毒性聚集。在细胞中，几个因素确保了有效的折叠。折叠开始共同- 当核糖体仍在合成多肽时。分子伴侣开始 一旦新生的多结构域蛋白从核糖体中出现，就与之相互作用。共- 翻译折叠和分子伴侣相互作用被认为是有效的多结构域 蛋白质折叠。然而，这些过程在分子水平上的定义仍然很差，因为它是 在技术上很难研究它们。这个项目的目标是定义共同翻译的原则 折叠和伴侣蛋白的功能，以更好地了解复杂的多结构域蛋白质如何稳健地达到 其功能结构。我们将单分子生物物理学和活细胞 实验来实现这个目标。利用光镊，我们正在研究 在单分子水平上的新生多结构域蛋白。操纵单个分子是 非常适合解析新生蛋白质的复杂折叠途径，阐明了 核糖体和分子伴侣的折叠过程，并确定如何共翻译 折叠和蛋白质合成被耦合和调节以确保稳健的结果。这些细节在 体外研究还得到了活细胞实验的补充， 在多结构域蛋白质中。蛋白质错误折叠和聚集，蛋白质合成的错误调节， 伴侣蛋白功能的下降是许多衰老相关疾病的标志。我们的研究最终可能 为发现新的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.