Genetic robustness and selection at the protein level for synonymous codons
Genetic robustness and selection at the protein level for synonymous codons
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DOI：
10.1111/j.1420-9101.2005.01029.x
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发表时间：
2006-03-01
影响因子：
2.1
通讯作者：
Archetti, M
中科院分区：
文献类型：
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作者：
Archetti, M
同义密码子在蛋白质水平上是中性的，因此蛋白质水平上的自然选择对其频率没有影响。然而，同义密码子在减少错误影响的能力上有所不同：突变后，某些密码子继续编码相同的氨基酸或具有相似性质的氨基酸，而其他同义密码子产生非常不同的氨基酸。因此，错误对编码序列的影响（遗传稳健性）可以通过分析其密码子使用来测量。我分析了测序的细胞核和细胞质基因组的密码子使用，我表明，在DNA序列水平上，基因组之间和同一基因组的基因之间的遗传鲁棒性存在广泛的变化。我还从理论上证明了鲁棒性可以是自适应的，也就是说，自然选择可能会导致对减少错误影响的密码子的偏好。然而，如果选择仅发生在密码子的突变体中（例如在成年期之前的后代中），则对突变效应更敏感的密码子的频率可能会增加，因为它们更容易摆脱有害突变。我还提出了在密码子水平上对遗传稳健性进化的其他可能解释。
Synonymous codons are neutral at the protein level, therefore natural selection at the protein level should have no effect on their frequencies. Synonymous codons, however, differ in their capacity to reduce the effects of errors: after mutation, certain codons keep on coding for the same amino acid or for amino acids with similar properties, while other synonymous codons produce very different amino acids. Therefore, the impact of errors on a coding sequence (genetic robustness) can be measured by analysing its codon usage. I analyse the codon usage of sequenced nuclear and cytoplasmic genomes and I show that there is an extensive variation in genetic robustness at the DNA sequence level, both among genomes and among genes of the same genome. I also show theoretically that robustness can be adaptive, that is natural selection may lead to a preference for codons that reduce the impact of errors. If selection occurs only among the mutants of a codon (e.g. among the progeny before the adult phase), however, the codons that are more sensitive to the effects of mutations may increase in frequency because they manage to get rid more easily of deleterious mutations. I also suggest other possible explanations for the evolution of genetic robustness at the codon level.