Studies on start codon selection by eukaryotic ribosomes

真核核糖体起始密码子选择的研究

• 批准号: 6994424
• 负责人: KATSURA ASANO
• 金额: $ 20.89万
• 依托单位: KANSAS STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6994424
• 关键词: Saccharomyces cerevisiae; fungal genetics; genetic models; genetic translation; guanosinetriphosphatase activating protein; messenger RNA; nucleic acid sequence; ribosomes; transfer RNA; translation factor

DESCRIPTION (provided by applicant): Translation initiation is the rate-limiting step of protein biosynthesis and an important target for the control of gene expression. Unregulated translation initiation can result in malignant transformation of cells. The yeast Saccharomyces cerevisiae is a genetically tractable eukaryotic microorganism, which has proven to be an excellent model system to study a variety of cellular processes including translation initiation. The aim of this project is to understand at the molecular level, using S. cerevisiae as a model organism, how eukaryotic ribosomal initiation complexes stringently select AUG as a start codon. Extensive genetic and biochemical studies conducted by the Donahue group at the Indiana University implicated eukaryotic initiation factor 1 (elFi), elF5, and all three subunits of elF2 in the stringent AUG selection for yeast mRNAs. elF5 acts as a GTPase activating protein (GAP) for elF2 on correct AUG recognition. Working with Dr. HInnebusch at the NIH, I recently showed that a five-subunit factor elF3 binds to both eIF1 and elF5, and that the C-terminal domain (CTD) of elF5 bridges interaction between elF2 and elF3. The elF1/elF3/elF5/ elF2 multifactor complex occurs free of the ribosome and contains stoichiometric amount of the methionyl initiator tRNA. When bound to the ribosome, the multifactor complex interacts (also via elF5-CTD) with elF4F bound to m7G-capped mRNA. Here I hypothesize that the multiple interactions mediated by the eIF5-CTD stimulate formation of 40S ribosomal preinitiation complexes and also promote scanning and stringent selection of AUG codons. I also propose a model for how the elF2 GTPase is activated on correct AUG recognition via direct elF2-elF5 (GAP) interation. I would like to test these models with mutagenesis studies on elF5 and elF4G, in combination with sophisticated biochemical techniques adapted from studies on mammalian systems.

描述（由申请人提供）：翻译启动是 蛋白质生物合成的速率限制步骤和一个重要目标 控制基因表达。不受管制的翻译启动可能会导致 细胞的恶性转化。酿酒酵母的酵母菌是 遗传上可牵引的真核微生物，事实证明是 出色的模型系统研究各种蜂窝过程 翻译启动。该项目的目的是了解 分子水平，使用酿酒酵母作为模型生物，真核如何 核糖体启动复合物严格选择AUG作为起始密码子。 Donahue组在 印第安纳大学与真核开始因子1（ELFI），ELF5和 ELF2的所有三个亚基在严格的Aug选择酵母mRNA中。 ELF5 在正确的AUM识别上充当ELF2的GTPase激活蛋白（GAP）。 与NIH的Hinnebusch博士合作，我最近表明了一项五个亚基 因子ELF3与EIF1和ELF5结合，并且C末端结构域（CTD） Elf5桥的相互作用Elf2和Elf3之间的相互作用。 ELF1/ELF3/ELF5/ELF2 多因素复合物发生无核糖体，并包含化学计量学 甲基蛋白酶引发剂tRNA的量。当绑定到核糖体时 多因素复合物与ELF4F的相互作用（也通过ELF5-CTD）结合到 M7G覆盖的mRNA。在这里，我假设由 EIF5-CTD刺激40S核糖体预启发复合物的形成和 还可以促进扫描和严格选择Aug密码子。我也建议 如何在正确的AUG识别中激活ELF2 GTPase的模型 直接ELF2-ELF5（GAP）相互作用。我想用 对ELF5和ELF4G的诱变研究，结合复杂的 生化技术适合于哺乳动物系统的研究。