Studies on start codon selection by eukaryotic ribosomes

调节失调的转位启动通过不同的方式引起恶变或其他慢性疾病 机械装置。因此，对翻译启动机制的研究有助于增进人类健康 和幸福。这项提议的长期目标是了解导致 准确启动翻译。在翻译启动中，真核细胞启动因子1(ELF1)、ELF5和ALL ElF2的三个亚基与酵母mRNAs的严格AUG选择有关。C端子 ELF5的结构域(CTD)结合ElF1并桥接ElF2和五亚基因子ElF3之间的相互作用， 介导多因子复合体(MFC)的形成，该复合体还包含甲硫基启动子tRNA。什么时候 与核糖体结合，MFC相互作用重新排列，允许ELF5-CTD与elF4G亚基相互作用 ElF4F复合体与S封顶的基因结合，促进核糖体起始前复合体的形成。 根据GM67841提案的先前目标，有证据表明，翻译的准确性 MFC的启动取决于MFC的功能，但这种复合体如何组装和发挥功能仍不清楚。 特别是，将MFC和预引发复合体的功能与 单个精灵的结构，已经开始揭开面纱。与哈佛大学的格哈德·瓦格纳博士合作 医学院，Asano小组已经解决了酵母Elf1的结构，并确定了它与 ElF2和elFSc的NTDS和elF4G和ELF5的CTDS。基因和生物化学研究表明 这些相互作用可能会在预引发复合体的组装和功能过程中重新排列。在这次更新中 提议，第一个目标是与瓦格纳小组合作解决ELF5-CTD的结构，并使用 这些信息将指导其精心设计的诱变研究。第二个目标是重建完全的MFC 从纯化的成分中提取，并利用它来了解其组装激活和 假说通过ELF5的磷酸化控制。最后，第三个目标是研究MFC的关键合作伙伴 在预引发复合体中，elF4G-CTD和核糖体RNA。从以前的目标中获得的数据 将用于预测elF4G-CTD的ELF5-CTD结合面并进行定点突变研究 关于后者。根据前一提案中的目标获得的rRNA中的&gt；30 ts-突变映射将是 与新的突变一起使用，将在预测的40s亚基与mRNA的界面引入。

Dysregulated translaion initiation causes malignant transformation or other chronic diseases by different mechanisms. Therefore, studies on the mechanism of translation initiation help to enhance human health and well being. The long-term goal of this proposal is to understand the complex pathway leading to the accurate initiation of translation. In translation initiation, eukaryotic initiation factor 1 (elF1), elF5, and all three subunits of elF2 are implicated in the stringent AUG selection for yeast mRNAs. The C-terminal domain (CTD) of elF5 binds elF1 and bridges interaction between elF2 and a five-subunit factor elF3, mediating fomration of the multifactor complex (MFC) which also contains the methionyl initiator tRNA. When bound to the ribosome, the MFC interactions rearrange, allowing elF5-CTD to interact with the elF4G subunit of elF4F complex bound to S'-capped mRNA and promoting formation of ribosomal preinitiation complex. Under the previous aims in this GM67841 proposal, evidence was provided that the accuracy of translation initiation depends on the function of the MFC, but how this complex assembles and functions is still unclear. In particular, it is very important to correlate the functions of the MFC and preinitiation complexes to the structure of individual elFs, which has started to unveil. In collaboration with Dr. Gerhard Wagner at Harvard Medical School, the Asano group has solved the structure of yeast elF1 and identified its interfaces to the NTDs of elF2¿ and elFSc and the CTDs of elF4G and elF5. Genetic and biochemical studies showed how these interactions may rearrange during preinitiation complex assembly and function. In this renewal proposal, the first aim is to solve the structure of elF5-CTD in collaboration with the Wagner group, and use this information to direct its well-designed mutagenesis studies. The second aim is to reconstitute full MFC from purified constituents, and use it to understand the mechanism of its assembly activation and hypothetical control by elF5 phosphorylation. Finally, the third aim is to study the critical partners of the MFC in the preinitiation complex, elF4G-CTD and the ribosomal RNA. The data obtained from the previous aims will be used to predict elF5-CTD-binding face of elF4G-CTD and perform site-directed mutagenesis studies on the latter. >30 Ts- mutations mapping in rRNA obtained under an aim in the previous proposal will be used together with new mutations to be introduced at the predicted 40S subunit interface to mRNA.