Targeting ubiquitylated proteins to the proteasome

将泛素化蛋白质靶向蛋白酶体

基本信息

批准号：
7666762
负责人：
HAI RAO
金额：
$ 25.91万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-08-01 至 2012-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7666762
关键词：
ATP-Dependent Proteases Adaptor Signaling Protein Affect Binding Binding Proteins Biochemical Biological Biological Process Biology Cell Cycle Progression Cell physiology Cells Coenzyme A Complex Couples DNA Repair Destinations Elements Elongation Factor Enzymes Eukaryota Future Genetic Genetic Transcription Goals Human Hydrolysis In Vitro Intervention Lysine Mediating Molecular Chaperones Molecular Target Mutation Oxidoreductase Pathway interactions Play PrP Prion Diseases Prions Process Property Proteasome Binding Proteins Proteolysis Regulation Role Saccharomyces cerevisiae Signal Transduction Stress Response Signaling Substrate Specificity System Ubiquitin Ubiquitination Work Yeasts base cofactor human disease in vitro Assay in vivo insight interest multicatalytic endopeptidase complex mutant novel prion biogenesis protein degradation transcription factor

项目摘要

DESCRIPTION (provided by applicant): Our long-term goal is to understand how the fate of proteins is regulated by the ubiquitin (Ub) system. Ub, an abundant 76-residue protein, is highly conserved among eukaryotes. Ubiquitylation - the covalent conjugation of Ub to lysine residues on other intracellular proteins - regulates a myriad of cellular processes, including cell cycle progression, DNA repair, transcription, stress responses and signal transduction. Ub is best known as a signal to target proteins for destruction by a multisubunit, ATP dependent protease termed the proteasome. How the substrates are delivered to the proteasome is one of the most challenging issues in the field. It is proposed that adaptor molecules, which selectively recognize ubiquitylated substrates, perform this vital function in deciding the final destination of substrates. We will focus on S. cerevisiae Rad23, a candidate adaptor molecule involved in delivering ubiquitylated substrates to the proteasome. Rad23 has two functional domains: a ubiquitin-like element (UBL), and a ubiquitin-associated motif (UBA). The UBL motif was shown to directly bind the proteasome subunit Rpn1. Several groups including ours found that the UBA domain preferentially binds ubiquitylated substrates. And yeast cells lacking Rad23 are deficient in proteolysis. Importantly, Rad23 promotes the formation of the proteasome-Ub conjugates complex in vivo and in vitro. More recently, we found that Rad23 and Dsk2 interact with Ufd2, an E4 enzyme important for Ub-chain assembly. Based on biochemical properties and genetic evidence, we propose that Rad23-like adaptor proteins recognize multi-ubiquitylated substrates and deliver them to the proteasome through various binding partners. The yeast Ufd2-Rad23 complex regulates the degradation of UFD substrates, Hmg-CoA reductase, and the transcription factor Spt23, and prion protein. We propose the following aims in an effort to decipher the biological role of the adaptor molecules in substrate proteolysis. Aim 1 is to understand the mechanism underlying the substrate selectivity of Rad23. Aim 2 is to determine the regulation of the Rad23-Ufd2 complex. Aim 3 is to define the function of Rad23-mediated proteolysis in prion biogenesis. These studies should reveal novel insights into the mechanisms and functions of the Ub system, and provide defined molecular targets for future intervention in human diseases.

描述（由申请人提供）：我们的长期目标是了解泛素 (Ub) 系统如何调节蛋白质的命运。 Ub 是一种丰富的 76 个残基蛋白质，在真核生物中高度保守。泛素化（Ub 与其他细胞内蛋白质上的赖氨酸残基的共价结合）调节多种细胞过程，包括细胞周期进程、DNA 修复、转录、应激反应和信号转导。 Ub 最出名的是作为目标蛋白质的信号，以便被多亚基、ATP 依赖性蛋白酶（称为蛋白酶体）破坏。如何将底物递送至蛋白酶体是该领域最具挑战性的问题之一。有人提出，选择性识别泛素化底物的接头分子在决定底物的最终目的地方面发挥着重要作用。我们将重点关注酿酒酵母 Rad23，这是一种候选接头分子，参与将泛素化底物传递至蛋白酶体。 Rad23 有两个功能域：泛素样元件 (UBL) 和泛素相关基序 (UBA)。 UBL 基序显示可直接结合蛋白酶体亚基 Rpn1。包括我们在内的几个小组发现 UBA 结构域优先结合泛素化底物。缺乏 Rad23 的酵母细胞缺乏蛋白水解作用。重要的是，Rad23 在体内和体外促进蛋白酶体-Ub 缀合物复合物的形成。最近，我们发现 Rad23 和 Dsk2 与 Ufd2 相互作用，Ufd2 是一种对 Ub 链组装很重要的 E4 酶。基于生化特性和遗传证据，我们提出 Rad23 样接头蛋白可识别多泛素化底物，并通过各种结合伙伴将其递送至蛋白酶体。酵母 Ufd2-Rad23 复合物调节 UFD 底物、Hmg-CoA 还原酶、转录因子 Spt23 和朊病毒蛋白的降解。我们提出以下目标，以努力破译接头分子在底物蛋白水解中的生物学作用。目标 1 是了解 Rad23 底物选择性的潜在机制。目标 2 是确定 Rad23-Ufd2 复合物的调节。目标 3 是确定 Rad23 介导的蛋白水解在朊病毒生物合成中的功能。这些研究应该揭示对 Ub 系统的机制和功能的新见解，并为未来干预人类疾病提供明确的分子靶标。