Duret L, Mouchiroud D
Laboratoire de Biométrie, Génétique et Biologie des Populations, Unité Mixte de Recherche Centre National de la Recherche Scientifique 5558, Villeurbanne Cedex, France.
Proc Natl Acad Sci U S A. 1999 Apr 13;96(8):4482-7. doi: 10.1073/pnas.96.8.4482.
We measured the expression pattern and analyzed codon usage in 8,133, 1,550, and 2,917 genes, respectively, from Caenorhabditis elegans, Drosophila melanogaster, and Arabidopsis thaliana. In those three species, we observed a clear correlation between codon usage and gene expression levels and showed that this correlation is not due to a mutational bias. This provides direct evidence for selection on silent sites in those three distantly related multicellular eukaryotes. Surprisingly, there is a strong negative correlation between codon usage and protein length. This effect is not due to a smaller size of highly expressed proteins. Thus, for a same-expression pattern, the selective pressure on codon usage appears to be lower in genes encoding long rather than short proteins. This puzzling observation is not predicted by any of the current models of selection on codon usage and thus raises the question of how translation efficiency affects fitness in multicellular organisms.
我们分别测量了秀丽隐杆线虫、黑腹果蝇和拟南芥中8133个、1550个和2917个基因的表达模式，并分析了密码子使用情况。在这三个物种中，我们观察到密码子使用与基因表达水平之间存在明显的相关性，并表明这种相关性并非由突变偏差导致。这为在这三种远缘多细胞真核生物的沉默位点上进行选择提供了直接证据。令人惊讶的是，密码子使用与蛋白质长度之间存在很强的负相关性。这种效应并非由于高表达蛋白质的较小尺寸所致。因此，对于相同的表达模式，在编码长蛋白质而非短蛋白质的基因中，密码子使用上的选择压力似乎更低。这种令人困惑的观察结果并未被当前任何关于密码子使用选择的模型所预测，因此提出了翻译效率如何影响多细胞生物适应性的问题。
