DNA-SEQUENCE EVOLUTION - THE SOUNDS OF SILENCE
DNA-SEQUENCE EVOLUTION - THE SOUNDS OF SILENCE
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DOI：
10.1098/rstb.1995.0108
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发表时间：
1995-09-29
影响因子：
6.3
通讯作者：
PEDEN, JF
中科院分区：
文献类型：
--
作者：
SHARP, PM;AVEROF, M;PEDEN, JF
蛋白质编码基因中的沉默位点（可以进行同义替换的位置）可以阐明两个进化过程。首先，尽管沉默寡言，但它们可能会受到自然选择的影响。在真核生物中，酵母就是一个例子，在酵母中，同义密码子的使用模式是通过选择特定的密码子来形成的，这些密码子被最丰富的trna更有效和/或准确地翻译；密码子在整个基因组中的使用，以及不同tRNA物种的丰度，都是高度共适应的。其次，在没有选择的情况下，沉默位点揭示了潜在的突变模式。密码子的使用在人类基因中差异很大，但沉默位点似乎不受自然选择的影响，这表明基因组不同区域的突变模式不同。起初，酵母和人类基因组被认为反映了单细胞和多细胞生物之间的二分法。然而，现在看来，自然选择在一些多细胞物种（如果蝇和隐杆线虫）中塑造了密码子的使用，并且在酵母中发生了突变偏差的区域差异。沉默位点（丝氨酸密码子）也提供了突变事件同时改变相邻核苷酸的证据。
Silent sites (positions that can undergo synonymous substitutions) in protein-coding genes can illuminate two evolutionary processes. First, despite being silent, they may be subject to natural selection. Among eukaryotes this is exemplified by yeast, where synonymous codon usage patterns are shaped by selection for particular codons that are more efficiently and/or accurately translated by the most abundant tRNAs; codon usage across the genome, and the abundance of different tRNA species, are highly co-adapted. Second, in the absence of selection, silent sites reveal underlying mutational patterns. Codon usage varies enormously among human genes, and yet silent sites do not appear to be influenced by natural selection, suggesting that mutation patterns vary among regions of the genome. At first, the yeast and human genomes were thought to reflect a dichotomy between unicellular and multicellular organisms. However, it now appears that natural selection shapes codon usage in some multicellular species (e.g. Drosophila and Caenorhabditis), and that regional variations in mutation biases occur in yeast. Silent sites (in serine codons) also provide evidence for mutational events changing adjacent nucleotides simultaneously.