CORRELATION BETWEEN THE ABUNDANCE OF ESCHERICHIA-COLI TRANSFER-RNAS AND THE OCCURRENCE OF THE RESPECTIVE CODONS IN ITS PROTEIN GENES - A PROPOSAL FOR A SYNONYMOUS CODON CHOICE THAT IS OPTIMAL FOR THE ESCHERICHIA-COLI TRANSLATIONAL SYSTEM
CORRELATION BETWEEN THE ABUNDANCE OF ESCHERICHIA-COLI TRANSFER-RNAS AND THE OCCURRENCE OF THE RESPECTIVE CODONS IN ITS PROTEIN GENES - A PROPOSAL FOR A SYNONYMOUS CODON CHOICE THAT IS OPTIMAL FOR THE ESCHERICHIA-COLI TRANSLATIONAL SYSTEM
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DOI：
10.1016/0022-2836(81)90003-6
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发表时间：
1981-01-01
影响因子：
5.6
通讯作者：
IKEMURA, T
中科院分区：
文献类型：
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作者：
IKEMURA, T
26种已知的E.大肠杆菌中的大肠杆菌（Ikemura，1981）。基于这种相对丰度，同源密码子在E.大肠杆菌基因和转座子和大肠杆菌噬菌体基因进行了检测。大多数大肠杆菌的tRNA含量与其密码子的出现率呈强正相关。已经测序的大肠杆菌基因，尽管转座子和噬菌体基因的相关性不太显著。在E.编码丰富蛋白质的大肠杆菌基因对tRNA含量的影响尤其明显，并且大于从2个变量之间的比例关系所预期的，即，这些基因选择性地使用对应于主要tRNA种类的密码子，但几乎完全避免使用次要tRNA种类的密码子。E.大肠杆菌基因被认为在很大程度上受到tRNA可用性的限制，并可能受到翻译效率的限制。基于同功tRNA的含量和密码子-反密码子相互作用的性质，可以预测大多数氨基酸的同义密码子之间的偏好顺序。以这种方式预测的同义密码子是最优选的密码子，被认为是针对E. coli翻译系统中的密码子，并将其指定为最佳密码子。E.大肠杆菌编码丰富蛋白质的基因选择性地使用最佳密码子，而其他大肠杆菌编码丰富蛋白质的基因选择性地使用最佳密码子。大肠杆菌基因如氨基酸合成基因使用最佳和非最佳密码子的程度大致相等。从进化的角度讨论了最佳密码子的使用频率与基因的表达水平密切相关。
The relative quantities of 26 known tRNA species of E. coli were previously measured (Ikemura, 1981). Based on this relative abundance, the usage of cognate codons in E. coli genes and in transposon and coliphage genes was examined. A strong positive correlation between tRNA content and the occurrence of respective codons was found for most E. coli genes that had been sequenced, although the correlation was less significant for transposon and phage genes. The dependence of the usage of isoaccepting tRNA, in E. coli genes encoding abundant proteins, on tRNA content was especially noticeable and was greater than that expected from the proportional relationship between the 2 variables, i.e., these genes selectively use codons corresponding to major tRNA species, but almost completely avoid using codons of minor tRNA species. Codon choice in E. coli genes was considered to be largely constrained by tRNA availability and possibly by translational efficiency. Based on the content of isoaccepting tRNA and the nature of codon-anticodon interaction, it was possible to predict for most amino acids the order of preference among synonymous codons. The synonymous codon predicted in this way to be the most preferred codon was thought to be optimized for the E. coli translational system and designated as the optimal codon. E. coli genes encoding abundant protein species use the optimal codons selectively, and other E. coli genes, such as amino acid synthesizing genes, use optimal and non-optimal codons to a roughly equal degree. The frequency of usage of optimal codons is closely correlated with the production levels of individual genes was discussed from an evolutionary viewpoint.