INVESTIGATIONS OF REACTIONS OF PHYSIOLOGICAL IMPORTANCE

生理重要性反应的调查

基本信息

批准号：
6385001
负责人：
PAUL R SCHIMMEL
金额：
$ 50.92万
依托单位：
SCRIPPS RESEARCH INSTITUTE, THE
依托单位国家：
美国
项目类别：
财政年份：
1979
资助国家：
美国
起止时间：
1979-06-01 至 2003-05-31
项目状态：
已结题

项目摘要

This project deals with the decoding of genetic information in translation. Specifically, the project focuses on the establishment of the roles of the genetic code by the aminocylation reactions that are catalyzed by aminoacyl tRNA synthetases. In these reactions, amino acids are matched with their cognate transfer RNAs which contain the anti- codon triplets of the code. The transfer RNAs are ancient molecules that are thought to have developed in an RNA world, while the synthetases were likely among the early proteins to emerge from an RNA world as the genetic code was established. Much effort is directed at understanding RNA-dependent amino acid discrimination in translational editing. In this reaction, the accuracy of the code is enhanced through an RNA- dependent refinement of the discrimination of closely similar amino acids. Here, the synthetase-tRNA complex functions in amino acid recognition as a ribonucleoprotein (RNP) that is perhaps reminiscent of an early development of synthetases as RNPs. A second goal is to understand how domains within a synthetase communicate, within the synthetase-tRNA complex. To a rough approximation, the two major domains of a tRNA interact separately with two domains in a tRNA synthetase. In particular, the primordial synthetase is thought to be represented by a catalytic domain that recognizes nucleotides determinants near the amino acid attachment site. This interaction is sufficient to catalyze aminoacylation of RNA oligonucleotide substrates known as microhelices that are based on just the accepted end of the tRNA. The relationship between nucleotide determinants in acceptor stems and the attached amino acid constitutes an operational RNA ode for amino acids that is distinct from the nucleotide triplets of the genetic code. For some synthetases the interaction of its second domain with the second anti-contain domain of the tRNA greatly enhances the rate of the aminoacylation by an unknown mechanism. A third goal is to see whether aminoacylated microhelix substrates can be used for peptide synthesis, in a ribosome- free system. Such a system could be representative of an early system for protein synthesis. Collectively, these investigations expand our understanding of the genetic code and the biochemical mechanisms that are its underpinnings. They also give clues into the possible connections between the RNA world an the theater of proteins. Because they are essential and show species-specific variations through evolution, the synthetases and tRNAs are ideal targets for therapeutic drugs directed at infectious pathogens. An expanded understanding of these systems could, therefore, have direct applications to human health.

该项目涉及翻译中遗传信息的解码。具体来说，该项目的重点是通过氨酰 tRNA 合成酶催化的氨酰化反应来确定遗传密码的作用。在这些反应中，氨基酸与其含有反密码子三联体的同源转移RNA相匹配。转移RNA是古老的分子，被认为是在RNA世界中发展起来的，而合成酶很可能是随着遗传密码的建立而从RNA世界中出现的早期蛋白质之一。许多努力致力于理解翻译编辑中依赖于 RNA 的氨基酸区分。在此反应中，通过依赖于 RNA 的精确区分非常相似的氨基酸，提高了代码的准确性。此处，合成酶-tRNA 复合物作为核糖核蛋白 (RNP) 进行氨基酸识别，这可能让人想起合成酶作为 RNP 的早期发展。第二个目标是了解合成酶-tRNA 复合物中合成酶内的结构域如何进行通信。粗略估计，tRNA 的两个主要结构域分别与 tRNA 合成酶中的两个结构域相互作用。特别地，原始合成酶被认为由识别氨基酸附着位点附近的核苷酸决定簇的催化结构域代表。这种相互作用足以催化 RNA 寡核苷酸底物（称为微螺旋）的氨酰化，微螺旋仅基于 tRNA 的可接受末端。受体茎中的核苷酸决定簇和所附着的氨基酸之间的关系构成了氨基酸的可操作RNA代码，其与遗传密码的核苷酸三联体不同。对于某些合成酶，其第二个结构域与 tRNA 的第二个反包含结构域的相互作用通过未知机制大大提高了氨酰化的速率。第三个目标是了解氨酰化微螺旋底物是否可用于无核糖体系统中的肽合成。这样的系统可以代表早期蛋白质合成系统。总的来说，这些研究扩展了我们对遗传密码及其基础生化机制的理解。它们还为 RNA 世界与蛋白质剧场之间可能的联系提供了线索。因为它们是必需的，并且在进化过程中表现出物种特异性的变异，所以合成酶和 tRNA 是针对传染性病原体的治疗药物的理想靶标。因此，对这些系统的进一步了解可以直接应用于人类健康。