真菌 CTG 分支的遗传密码。

The genetic code of the fungal CTG clade.

机构信息

RNA Biology Laboratory, Department of Biology and CESAM, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.

出版信息

C R Biol. 2011 Aug-Sep;334(8-9):607-11. doi: 10.1016/j.crvi.2011.05.008. Epub 2011 Jul 2.

DOI:10.1016/j.crvi.2011.05.008

PMID:21819941

Abstract

Genetic code alterations discovered over the last 40 years in bacteria and eukaryotes invalidate the hypothesis that the code is universal and frozen. Mitochondria of various yeast species translate the UGA stop codon as tryptophan (Trp) and leucine (Leu) CUN codons (N = any nucleotide) as threonine (Thr) and fungal CTG clade species reassigned Leu CUG codons to serine and translate them ambiguously in their cytoplasms. This unique sense-to-sense genetic code alteration is mediated by a Ser-tRNA containing a Leu 5'-CAG-3'anticodon (ser-tRNA(CAG)), which is recognized and charged with Ser (~~97%) by the seryl-tRNA synthetase (SerRS) and with Leu (~~3%) by the leucyl-tRNA synthetase (LeuRS). This unusual tRNA appeared 272 ± 25 million years ago and had a profound impact on the evolution of the CTG clade species. Here, we review the most recent results and concepts arising from the study of this codon reassignment and we highlight how its study is changing our views of the evolution of the genetic code.

摘要

在过去的 40 年中，在细菌和真核生物中发现的遗传密码改变否定了密码是普遍存在且冻结不变的假设。各种酵母物种的线粒体将 UGA 终止密码子翻译为色氨酸（Trp）和亮氨酸（Leu）CUN 密码子（N = 任何核苷酸）为苏氨酸（Thr），真菌 CTG 分支物种重新分配 Leu CUG 密码子为丝氨酸，并在细胞质中含糊地翻译它们。这种独特的意义到意义的遗传密码改变是由一种含有亮氨酸 5'-CAG-3'反密码子的 Ser-tRNA 介导的（ser-tRNA(CAG)），它被丝氨酸-tRNA 合成酶（SerRS）识别并以丝氨酸 (~~97%) 加载，被亮氨酸-tRNA 合成酶（LeuRS）以亮氨酸 (~~3%) 加载。这种不寻常的 tRNA 出现在 2.72 ± 0.25 亿年前，对 CTG 分支物种的进化产生了深远的影响。在这里，我们回顾了从这个密码子重排研究中得出的最新结果和概念，并强调了它的研究如何改变我们对遗传密码进化的看法。