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：
7262076
负责人：
HAI RAO
金额：
$ 28.35万
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/7262076
关键词：
ATP-Dependent Proteases Adaptor Signaling Protein Affect Binding Binding Proteins Biochemical Biochemical Genetics Biological Biological Process Biology Cell Cycle Progression Cell physiology Cells Coenzyme A Complex Couples DNA Repair Destinations Elements Elongation Factor Enzymes Eukaryota Eukaryotic Cell Future Genetic Genetic Transcription Goals Human Hydrolysis In Vitro Intervention Lysine Mediating Molecular Chaperones Molecular Target Mutation Oxidoreductase Pathway interactions Play 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蛋白质的命运如何受泛素（UB）系统调节。 UB是一种丰富的76个残留蛋白，在真核生物中是高度保守的。泛素化 - UB与其他细胞内蛋白质上的赖氨酸残基共轭 - 调节无数的细胞过程，包括细胞周期进程，DNA修复，转录，压力反应和信号转导。 UB最著名的是靶向蛋白质的信号，以通过多亚基的ATP蛋白酶称为蛋白酶体。如何将基材传递到蛋白酶体是该领域最具挑战性的问题之一。有人提出，在决定底物的最终目的地时，选择性地识别泛素化底物的适配器分子在确定最终目的地时会执行这一重要功能。我们将重点放在酿酒酵母Rad23上，这是一种候选衔接子分子，涉及将泛素化的底物传递到蛋白酶体。 RAD23具有两个功能域：泛素样元素（UBL）和一个泛素相关的基序（UBA）。显示UBL基序可直接结合蛋白酶体亚基RPN1。包括我们的几个组发现UBA域优先结合泛素化的底物。缺乏RAD23的酵母细胞缺乏蛋白水解。重要的是，RAD23促进了体内和体外的蛋白酶体 - UB结合物的形成。最近，我们发现RAD23和DSK2与UFD2相互作用，UFD2是一种对UB链组件重要的E4酶。基于生化特性和遗传证据，我们建议RAD23样衔接蛋白识别多泛素化的底物，并通过各种结合伙伴将其传递到蛋白酶体。酵母UFD2-RAD23复合物调节UFD底物，HMG-COA还原酶和转录因子SPT23和Prion蛋白的降解。我们提出以下目的，以破译衔接分子在底物蛋白水解中的生物学作用。目的1是了解RAD23底物选择性的基础机制。 AIM 2是确定Rad23-UFD2复合物的调节。目的3是定义Rad23介导的蛋白水解在prion生物发生中的功能。这些研究应揭示对UB系统机制和功能的新见解，并为未来干预人类疾病提供确定的分子靶标。