arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1910.13622q-bio.PE
收藏

论遗传编码的可能起源和进化

On the possible origin and evolution of genetic coding

Jacques H. Daniel

备注：
33 pages; 12 figures
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

为了与RNA一起合成肽，形成所谓的RNA世界，必须开发一些涉及RNA的遗传编码。在此，提出第一个实数编码设置是直接设置，由连续的多聚tRNA样分子组成，每个tRNA样部分在其5 ′或3 ′末端之外和附近携带用于特异性氨基酸结合的三核苷酸位点：特定多聚RNA的tRNA部分的序列和连续性，tRNA将确保相应肽或小蛋白质的氨基酸的序列和连续性。与这些特殊的实体平行，并增强它们的肽形成功能，原核糖体和原始氨基酸激活系统将发展。在某些阶段，一个关键的创新将是RNA片段的出现，其可以通过与位于或接近每个tRNA部分的中间（即，本反密码子位点）。这些RNA片段在肽合成装置中充当真正的共核酶，将构成目前mRNA的祖先。随后，在这些mRNA样引导片段上，将另外使用游离tRNA形式，首先保持它们的氨基酸-结合位点，然后失去它们，有利于在它们的3 ′末端的CCA臂处的特异性氨基酸附着。最后，后一种机制将逐渐占上风，导致现代和普遍的间接遗传编码系统。实验和理论的论点提出和讨论有利于这样一个场景的起源和进化的遗传编码。

英文摘要：

To synthesize peptides alongside the RNAs making the so-called RNA world, some genetic coding involving RNA had to develop. Herein, it is proposed that the first real-coding setup was a direct one, made up of continuous poly-tRNA-like molecules, with each tRNA-like moiety carrying, beyond and near its 5 prime or 3 prime end, a trinucleotide site for specific amino acid binding: the sequence and continuity of the tRNA moieties of a particular poly-tRNA would ensure the sequence and continuity of the amino acids of the corresponding peptide or small protein. In parallel with these particular entities, and enhancing their peptide-forming function, a proto-ribosome and primitive amino acid-activation system would develop. At some stage, one critical innovation would be the appearance of RNA fragments that could tighten several adjacent tRNA moieties together on a particular poly-tRNA molecule, by pairing with the second trinucleotide sequence (identical to the first one carrying the specific amino acid-binding site) situated at, or close to, the middle of each tRNA moiety (i.e., the present anticodon site). These RNA fragments, acting as authentic co-ribozymes in the peptide-synthesizing apparatus, would constitute the ancestors of the present mRNAs. Later, on these mRNA-like guiding fragments, free tRNA forms would be additionally used, first keeping their amino acid-binding sites, then losing them in favor of a specific amino acid attachment at a CCA arm at their 3 prime end. Finally, these latter mechanisms would progressively prevail, leading to the modern and universal indirect genetic coding system. Experimental and theoretical arguments are presented and discussed in favor of such a scenario for the origin and evolution of genetic coding.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑