Quality Control of Membrane Proteins

膜蛋白的质量控制

• 批准号: 8977647
• 负责人: Sanjay B Hari
• 金额: $ 5.42万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8977647
• 关键词: ATP phosphohydrolase; ATP-Dependent Proteases; Address; Affect; Bacteria; Bacterial Infections; Biochemical; Biological Sciences; C-terminal; Cell physiology; Cells; Complex; Data; Dissociation; Effectiveness; Ensure; Environment; Event; Genome; Goals; Health; Human; In Vitro; Kinetics; Label; Lead; Left; Lipid Bilayers; Location; Measures; Membrane; Membrane Proteins; Messenger RNA; Methods; Normal Cell; Organism; Peptide Hydrolases; Physiological; Predisposition; Property; Protein Fragment; Proteins; Proteomics; Quality Control; Ribosomes; Role; Source; System; Testing; Thermodynamics; Training; Transcript; Translations; Work; career; combat; cytotoxicity; feeding; fighting; insight; new therapeutic target; polypeptide; prevent; protein degradation; public health relevance; research study; response; therapeutic development; tmRNA

 DESCRIPTION (provided by applicant): Intracellular quality control mechanisms prevent misregulation and cytotoxicity. Protein degradation systems maintain protein quality by destroying potentially harmful incomplete or faulty polypeptides. Unfinished protein fragments are often the products of ribosomes that stall on mRNA transcripts. Ribosomal stalling also prevents normal termination and mRNA dissociation, thereby depleting the pool of ribosomes available for translation. In bacteria, a mechanism known as tmRNA rescue frees stalled ribosomes and marks incomplete proteins for destruction. Although this system has been studied in depth within the context of cytosolic proteins, relatively little is known about its effectiveness towards membrane proteins. Given that a significant portion of genomes of both simple and complex organisms encode membrane proteins, it is important to understand how stalling events of this type are handled and how protein quality control mechanisms operate in the challenging environment of the membrane interface. The overall goal of this project is to study the physiological response to ribosomes stalled during the synthesis of membrane proteins. Experiments conducted directly in bacteria will seek to understand the role of the tmRNA system in labeling incomplete membrane proteins for destruction as well as the role of specific proteases in degrading these proteins. The effect of membrane protein topology on degradation will also be ascertained. Next, quantitative proteomic methods will be used to determine the extent of endogenous membrane protein labeling by the tmRNA system and which of these proteins are degraded by proteases. Finally, an in vitro system will be developed to examine mechanistically the degradation of membrane proteins by different ATP-dependent proteases. It is expected that these experiments will yield a more comprehensive view of protein quality control in cells. A better understanding of protein quality control in bacteria could lead o the discovery of new targets for therapeutic development to combat bacterial infections.

 描述（由申请人提供）：细胞内质量控制机制可防止失调和细胞毒性。蛋白质降解系统通过破坏潜在有害的不完整或有缺陷的多肽来维持蛋白质质量。未完成的蛋白质片段通常是核糖体在 mRNA 转录物上停滞的产物。核糖体停滞还会阻止正常终止和 mRNA 解离，从而耗尽可用于翻译的核糖体池。在细菌中，一种称为 tmRNA 救援的机制可以释放停滞的核糖体，并标记不完整的蛋白质以进行破坏。尽管该系统已在胞质蛋白的背景下进行了深入研究，但对其对膜蛋白的有效性知之甚少。鉴于简单和复杂生物体的基因组的很大一部分都编码膜蛋白，因此了解如何处理此类失速事件以及蛋白质质量控​​制机制如何在膜界面的挑战性环境中运行非常重要。该项目的总体目标是研究膜蛋白合成过程中核糖体停滞的生理反应。直接在细菌中进行的实验将寻求了解 tmRNA 系统在标记不完整膜蛋白以进行破坏中的作用，以及特定蛋白酶在降解这些蛋白质中的作用。膜蛋白拓扑结构对降解的影响也将得到确定。接下来，定量蛋白质组学方法将用于确定 tmRNA 系统标记内源膜蛋白的程度以及这些蛋白质中哪些蛋白质被蛋白酶降解。最后，将开发一个体外系统来机械地检查不同 ATP 依赖性蛋白酶对膜蛋白的降解。预计这些实验将对细胞中蛋白质质量控​​制产生更全面的认识。更好地了解细菌中的蛋白质质量控​​制可能会导致发现对抗细菌感染的治疗开发的新靶标。