Tuite M F, Santos M A
Research School of Biosciences, University of Kent, Canterbury, UK.
Biochimie. 1996;78(11-12):993-9. doi: 10.1016/s0300-9084(97)86722-3.
A number of Candida species translate the standard leucine CUG codon as serine rather than as leucine. Such codon reassignment in nuclear-encoded mRNAs is unusual and raises a number of important questions about the origin of the genetic code and its continuing evolution. In particular we must establish how a codon can come to be reassigned without extinction of the species and what, if any, selective pressure drives such potentially catastrophic changes. Recent studies on the structure and identity of the novel CUG-decoding tRNA(Ser) from several different Candida species have begun to shed light on possible evolutionary mechanisms which could have facilitated such changes to the genetic code. These findings are reviewed here and a possible molecular mechanism proposed for how the standard leucine CUG codon could have become reassigned as a serine codon.
许多念珠菌属物种将标准的亮氨酸CUG密码子翻译为丝氨酸而非亮氨酸。核编码mRNA中的这种密码子重新分配并不常见，并引发了许多关于遗传密码起源及其持续进化的重要问题。特别是，我们必须确定一个密码子如何在物种不灭绝的情况下重新分配，以及是否有任何选择压力驱动这种潜在的灾难性变化。最近对几种不同念珠菌属物种的新型CUG解码tRNA(Ser)的结构和特性的研究，已开始揭示可能促成遗传密码这种变化的进化机制。本文对这些发现进行了综述，并提出了一种可能的分子机制，解释标准的亮氨酸CUG密码子如何可能重新分配为丝氨酸密码子。
