METABOLISM OF YEAST mRNAS THAT LACK A STOP CODON

缺乏终止密码子的酵母 mRNA 的代谢

• 批准号: 6913355
• 负责人: AMBRO VAN HOOF
• 金额: $ 25.25万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6913355
• 关键词: Saccharomyces cerevisiae; fungal genetics; fungal proteins; gene complementation; gene deletion mutation; gene expression; genetic regulation; genetic screening; genetic translation; immunoprecipitation; messenger RNA; northern blottings; nucleic acid metabolism; nucleic acid sequence; open reading frames; point mutation; proteasome; protein structure function; recombinant proteins; transcription factor

DESCRIPTION (provided by applicant): mRNA degradation is an important aspect of gene expression. It is now clear that the same enzymes degrade both stable and unstable mRNAs. Thus, the key to understanding differential mRNA degradation is to understand the interactions of a particular mRNA with the basal machinery. The experiments proposed here are aimed at understanding in molecular detail how one particular mRNA interacts with the mRNA decay machinery and how this causes its rapid degradation. This proposal is focused on the extremely rapid degradation of yeast mRNAs that lack a stop codon ("nonstop decay") for four reasons. First, nonstop mRNAs are the least stable mRNAs in yeast. Second, degradation of nonstop mRNAs is an important quality control aspect of gene expression. Third, the mechanism of nonstop decay is likely important to assure that mRNAs are completely degraded. Fourth, nonstop yeast mRNAs are degraded by a complex of 3' exonucleases (the exosome). The exosome is conserved between yeast and mammals and has many functions. These functions may include the decay of important mammalian mRNAs. Understanding nonstop decay in yeast should increase our understanding of other exosome functions. In the current model for nonstop mRNA degradation an mRNA is recognized as aberrant when a ribosome reaches its 3' end. This ribosome is recognized by Ski7p through the ribosomal A-site, which results in recruitment of the exosome. This proposal is aimed at testing and expanding this model. Aim 1 is to identify all parts of the cellular machinery for recognition and decay of nonstop mRNAs. Aim 2 is to characterize the role of these parts in vivo. Preliminary results suggest that the proteasome may degrade proteins encoded by nonstop mRNAs. Aim 3 is to test this hypothesis. The fourth aim is to characterize the function of Ski7p in detail, which is the key protein in nonstop mRNA recognition and recruitment of the basal mRNA decay machinery. These aims should result in an understanding of the recognition and decay of nonstop mRNAs in molecular detail. Since normal mRNAs are degraded by the same enzymes, these experiments should also increase our understanding of the degradation of normal cellular mRNAs.

描述（由申请人提供）：mRNA降解是基因表达的一个重要方面。现在很清楚，相同的酶可以降解稳定和不稳定的 mRNA。因此，了解差异 mRNA 降解的关键是了解特定 mRNA 与基础机制的相互作用。这里提出的实验旨在从分子细节上了解一种特定的 mRNA 如何与 mRNA 降解机制相互作用以及这如何导致其快速降解。该提案的重点是缺乏终止密码子（“不间断衰退”）的酵母 mRNA 的极快降解，原因有四个。首先，不间断 mRNA 是酵母中最不稳定的 mRNA。其次，不间断 mRNA 的降解是基因表达的重要质量控制方面。第三，不间断的衰变机制对于确保 mRNA 完全降解可能很重要。第四，不间断的酵母 mRNA 被 3' 核酸外切酶复合物（外泌体）降解。外泌体在酵母和哺乳动物之间是保守的，并且具有多种功能。这些功能可能包括重要哺乳动物 mRNA 的衰变。了解酵母的不间断腐烂应该会增加我们对其他外泌体功能的理解。在当前 mRNA 不间断降解模型中，当核糖体到达其 3' 末端时，mRNA 被认为是异常的。 Ski7p 通过核糖体 A 位点识别该核糖体，从而招募外泌体。该提案旨在测试和扩展该模型。目标 1 是识别识别和降解不间断 mRNA 的细胞机制的所有部分。目标 2 是表征这些部分在体内的作用。初步结果表明，蛋白酶体可能会降解由不间断 mRNA 编码的蛋白质。目标 3 是检验这个假设。第四个目标是详细描述 Ski7p 的功能，它是不间断 mRNA 识别和基础 mRNA 衰减机制招募的关键蛋白。这些目标应该导致我们在分子细节上了解不间断 mRNA 的识别和衰变。由于正常 mRNA 被相同的酶降解，这些实验也应该增加我们对正常细胞 mRNA 降解的理解。