INVESTIGATIONS OF REACTIONS OF PHYSIOLOGICAL IMPORTANCE

生理重要性反应的调查

• 批准号: 6180076
• 负责人: PAUL R SCHIMMEL
• 金额: $ 49.45万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 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
• 来源: https://reporter.nih.gov/project-details/6180076
• 关键词: active sites; aminoacid tRNA ligase; aminoacyl tRNA; biochemical evolution; conformation; enzyme inhibitors; enzyme mechanism; enzyme structure; enzyme substrate; enzyme substrate analog; enzyme substrate complex; genetic translation; mutant; nucleic acid sequence; nucleic acid structure; oligonucleotides; protein biosynthesis; protein sequence; ribonucleoproteins; ribosomes

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.

这个项目涉及翻译中遗传信息的解码。具体而言，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，氨基酸与其含有密码子的反密码子三联体的同源转移RNA匹配。转移RNA是被认为是在RNA世界中发展起来的古老分子，而合成酶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。许多努力是针对理解RNA依赖的翻译编辑中的氨基酸歧视。在该反应中，通过对非常相似的氨基酸的区分的RNA依赖性细化来增强编码的准确性。在这里，合成酶-tRNA复合物作为核糖核蛋白（RNP）在氨基酸识别中起作用，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内的结构域如何在合成酶-tRNA复合物内进行通信。大致上，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，原始合成酶被认为是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称为微螺旋的RNA寡核苷酸底物的氨酰化，微螺旋仅基于tRNA的可接受末端。受体茎中的核苷酸决定簇与所连接的氨基酸之间的关系构成了氨基酸的可操作RNA编码，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的机制大大提高了氨酰化的速率。第三个目标是观察氨酰化微螺旋底物是否可以在无核糖体系统中用于肽合成。这样的系统可能是早期蛋白质合成系统的代表。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世界和蛋白质剧场之间的可能联系提供了线索。因为它们是必需的，并且在进化过程中表现出物种特异性变异，合成酶和tRNA是针对感染性病原体的治疗药物的理想靶标。因此，扩大对这些系统的了解可以直接应用于人类健康。