密码子选择与基因表达：同义密码子在翻译准确性上存在差异。
Codon choice and gene expression: synonymous codons differ in translational accuracy.
作者信息
Dix D B, Thompson R C
机构信息
Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309.
出版信息
Proc Natl Acad Sci U S A. 1989 Sep;86(18):6888-92. doi: 10.1073/pnas.86.18.6888.
Ribosomes programmed by different synonymous codons also differ in discriminating among near-cognate aminoacylated tRNAs. In the initial step of the recognition reaction ribosomes programmed by UUC discriminate less well than ribosomes programmed by UUU against ternary complexes containing three types of Leu-tRNA, and ribosomes programmed by CUC discriminate less well than ribosomes programmed by CUU against ternary complexes containing Phe-tRNA. Furthermore, in the proofreading step ribosomes programmed by UUC discriminate less well than ribosomes programmed by UUU against two of three near-cognate Leu-tRNAs, and ribosomes programmed by CUC discriminate less well than ribosomes programmed by CUU against near-cognate Phe-tRNA. The codon-induced change in reaction rate with near-cognate ternary complexes is greater than that with cognate ternary complexes: the most efficient codon is, therefore, the least accurate. Because the efficient, but inaccurate, codon UUC is used preferentially in highly expressed mRNAs of Escherichia coli, maximization of translational accuracy apparently has not been significant in the evolution of this particular biased codon choice in E. coli.
由不同同义密码子编码的核糖体在区分近同源氨酰化tRNA方面也存在差异。在识别反应的初始步骤中，由UUC编码的核糖体对含有三种亮氨酸tRNA的三元复合物的区分能力不如由UUU编码的核糖体，而由CUC编码的核糖体对含有苯丙氨酸tRNA的三元复合物的区分能力不如由CUU编码的核糖体。此外，在校读步骤中，由UUC编码的核糖体对三种近同源亮氨酸tRNA中的两种的区分能力不如由UUU编码的核糖体，而由CUC编码的核糖体对近同源苯丙氨酸tRNA的区分能力不如由CUU编码的核糖体。密码子诱导的与近同源三元复合物反应速率的变化大于与同源三元复合物反应速率的变化：因此，最有效的密码子是最不准确的。由于高效但不准确的密码子UUC在大肠杆菌高表达mRNA中被优先使用，在大肠杆菌这种特定的偏向密码子选择的进化过程中，翻译准确性的最大化显然并不显著。
Zotero 插件