Bulmer M
Department of Statistics, Oxford University, England.
Genetics. 1991 Nov;129(3):897-907. doi: 10.1093/genetics/129.3.897.
It is argued that the bias in synonymous codon usage observed in unicellular organisms is due to a balance between the forces of selection and mutation in a finite population, with greater bias in highly expressed genes reflecting stronger selection for efficiency of translation. A population genetic model is developed taking into account population size and selective differences between synonymous codons. A biochemical model is then developed to predict the magnitude of selective differences between synonymous codons in unicellular organisms in which growth rate (or possibly growth yield) can be equated with fitness. Selection can arise from differences in either the speed or the accuracy of translation. A model for the effect of speed of translation on fitness is considered in detail, a similar model for accuracy more briefly. The model is successful in predicting a difference in the degree of bias at the beginning than in the rest of the gene under some circumstances, as observed in Escherichia coli, but grossly overestimates the amount of bias expected. Possible reasons for this discrepancy are discussed.
有人认为，在单细胞生物中观察到的同义密码子使用偏好是由于有限种群中选择力和突变力之间的平衡，高表达基因中更大的偏好反映了对翻译效率更强的选择。开发了一个考虑种群大小和同义密码子之间选择差异的群体遗传模型。然后开发了一个生化模型，以预测单细胞生物中同义密码子之间选择差异的大小，其中生长速率（或可能的生长产量）可等同于适合度。选择可能源于翻译速度或准确性的差异。详细考虑了翻译速度对适合度影响的模型，对准确性的类似模型则简要介绍。该模型在某些情况下成功地预测了基因开头比其余部分偏好程度的差异，如在大肠杆菌中观察到的那样，但严重高估了预期的偏好量。讨论了这种差异的可能原因。
