Functions of 4.5S RNA in the bacterial cell

4.5S RNA 在细菌细胞中的功能

• 批准号: 7047824
• 负责人: James Gregory PHILLIPS
• 金额: $ 14.04万
• 依托单位: IOWA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7047824
• 关键词: Escherichia coli; SDS polyacrylamide gel electrophoresis; affinity chromatography; bacterial RNA; cell membrane; genetic translation; peptides; protein biosynthesis; protein localization; protein protein interaction; protein signal sequence; protein structure function; ribonucleoproteins; transcription factor

DESCRIPTION (provided by applicant): The signal recognition particle (SRP) is a highly evolutionarily conserved ribonucleoprotein complex that functions to target proteins into biological membranes. Because E. coli contains a "minimal" SRP, consisting of the Ffh protein in association with a 4.5S RNA species, it provides an attractive system to understand how the translocation machinery functions in all living cells. Understanding the role of the RNA component of the bacterial SRP function is complicated by its essentiality for cell growth and its involvement in protein synthesis. Since few studies have been performed to understand how the sequence determinants of 4.5S RNA contribute to its function in vivo, little is known about why the RNA is an essential component of both the membrane protein localization and protein translation machinery. The long-term goal of our research is to determine how 4.5S RNA functions as a component of the SRP to target proteins to the inner membrane, and in translation by its interaction with elongation factor G. We propose to perform a systematic genetic characterization of 4.5S RNA to determine how the structure of this molecule contributes to its activity, and to probe the function of the RNA in both protein synthesis and membrane protein localization. Our lack of knowledge about the cellular roles of 4.5S RNA is significant in that it prevents us from fully describing the essential processes of protein localization and polypeptide synthesis on a molecular level. Due to the high evolutionary conservation of the SRP RNA, with homologues found in all living species examined to date, we will also better comprehend how this RNA species functions in all living systems. Although recent efforts have been placed largely on in vitro analysis of 4.5S RNA, including biochemical characterization and structural determinations, efforts to understand the function of 4.5 S RNA in vivo has lagged in part due to the lack of genetic systems for studying this molecule. These studies should contribute to improved methods to express and localize membrane proteins of medical importance, as well as lead to the identification of antimicrobial agents.

描述（由申请人提供）：信号识别颗粒（SRP）是一种高度进化保守的核糖核蛋白复合物，其功能是将蛋白质靶向生物膜。由于大肠杆菌含有“最小”SRP，由与 4.5S RNA 种类相关的 Ffh 蛋白组成，因此它提供了一个有吸引力的系统来了解易位机制如何在所有活细胞中发挥作用。了解细菌 SRP 功能中 RNA 成分的作用很复杂，因为它对于细胞生长及其参与蛋白质合成至关重要。由于很少有研究来了解 4.5S RNA 的序列决定因素如何影响其体内功能，因此对于为什么 RNA 是膜蛋白定位和蛋白质翻译机制的重要组成部分知之甚少。我们研究的长期目标是确定 4.5S RNA 作为 SRP 的一个组成部分如何发挥作用，将蛋白质靶向内膜，并通过其与延伸因子 G 的相互作用进行翻译。我们建议对4.5S RNA 以确定该分子的结构如何影响其活性，并探测 RNA 在蛋白质合成和膜蛋白定位中的功能。我们对 4.5S RNA 的细胞作用缺乏了解，这一点很重要，因为它阻止我们在分子水平上充分描述蛋白质定位和多肽合成的基本过程。由于 SRP RNA 的高度进化保守性，迄今为止在所有生物物种中都发现了同源物，我们还将更好地理解这种 RNA 物种如何在所有生命系统中发挥作用。尽管最近的努力主要集中在 4.5S RNA 的体外分析上，包括生化表征和结构测定，但了解 4.5S RNA 体内功能的努力却滞后，部分原因是缺乏研究该分子的遗传系统。这些研究应有助于改进表达和定位具有医学重要性的膜蛋白的方法，并有助于鉴定抗菌药物。