The role played by the RNAs and tRNAs in translation

描述（由申请人提供）：核糖体是两个亚基的大分子机器，负责将信使RNA解码为编码多肽-遗传密码的翻译。在完成这一重要的细胞作用时，核糖体执行了许多离散的功能，包括选择合适的氨基酰基tRNA，催化肽键形成（PT），准确地转运mRNA:tRNA复合物并释放完整的多肽链。生命起源的理论考虑预测了rna在翻译中的核心作用。RNA的催化作用、rRNA序列之间的极端保守性以及核糖体在功能关键区域主要显示rRNA的原子分辨率结构进一步证实了这一观点。我们工作的长期目标是了解核糖体功能的分子力学。我们特别感兴趣的是了解翻译机制中的rRNA和tRNA成分如何促进蛋白质合成的整个过程。原子分辨率结构信息和低分辨率低温电镜信息的出现极大地改变了我们近十年来的研究重点。虽然之前的挑战是确定位于功能关键区域的核糖体元素，但现在的目标是了解这些结构上确定的关键成分是如何起作用的。核糖体为解剖分子运动和研究它们如何定义生物学基础信号转导途径提供了一个极好的、易于处理的系统。所有三个特定目标都是围绕稳态前动力学方法和突变翻译成分的分析建立的，以在分子水平上解剖核糖体功能。我们特别感兴趣的是核糖体如何在感觉密码子上选择同源的氨基酰基trna和在停止密码子上选择合适的释放因子的分子细节，以及这些机制是如何相关的。本提案的一个主要新焦点是探索在肽键形成后发生的核糖体上的新型质量控制系统的机制特征。

DESCRIPTION (provided by applicant): The ribosome is the two-subunit macromolecular machine responsible for the decoding of the messenger RNA into the encoded polypeptide - the translation of the genetic code. In fulfilling this essential cellular role, ribosomes carry out a number of discrete functions including selecting the appropriate aminoacyl tRNAs, catalyzing peptide bond formation (PT), accurately translocating the mRNA:tRNA complex and releasing the completed polypeptide chain. Theoretical considerations of the origin of life predict a central role for the rRNAs in translation. This view has been strengthened by the demonstration of catalysis by RNA, extreme conservation observed among rRNA sequences and finally by atomic resolution structures of the ribosome displaying primarily rRNA in the functionally critical regions. The long-term goal of our work is to understand the molecular mechanics of ribosome function. We are particularly interested in understanding how the rRNA and tRNA components of the translation machinery contribute to the overall process of protein synthesis. The advent of atomic resolution structural information and lower resolution information from cryoEM has substantially changed the focus of our research during the past ten years. While the previous challenge was to identify elements of the ribosome located in functionally critical regions, the goal now is to understand how these structurally identified critical components function. The ribosome provides an excellent, tractable system for dissecting molecular movements and examining how they define biologically fundamental signal transduction pathways. All three specific aims are built around pre-steady state kinetic approaches and the analysis of mutated translation components to dissect ribosome function at the molecular level. We are particularly interested in the molecular details of how the ribosome selects the cognate aminoacyl-tRNA on sense codons and the appropriate release factor on stop codons, and how these mechanisms are related. A major new focus of this proposal is the exploration of the mechanistic features of a novel quality control system on the ribosome that takes place following peptide bond formation.