Positive Darwinian selection after gene duplication in primate ribonuclease genes
Positive Darwinian selection after gene duplication in primate ribonuclease genes
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DOI：
10.1073/pnas.95.7.3708
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发表时间：
1998-03-31
影响因子：
11.1
通讯作者：
Nei, M
中科院分区：
文献类型：
--
作者：
Zhang, JZ;Rosenberg, HF;Nei, M
新基因功能起源的进化机制一直是一个争论不休的话题。本文报道了一个令人信服的案例，证明在通过基因复制进化新功能的过程中，达尔文正选择在分子水平上起作用。灵长类嗜酸性粒细胞阳离子蛋白（ECP）和嗜酸性粒细胞衍生神经毒素（EDN）基因属于核糖核酸酶基因家族，ECP基因，其产物具有EDN不显示的抗病原体功能，是由大约3100万年前的EDN基因的复制产生的。使用祖先生物的推断核苷酸序列，我们表明ECP基因的非同义核苷酸取代的速率显著高于同义取代的速率，这有力地表明，在ECP基因进化的早期阶段，正达尔文选择起作用。还发现，在基因复制后的短时间内，精氨酸残基的数量大幅增加，这些氨基酸的变化可能产生了ECP新的抗病原体的功能。
Evolutionary mechanisms of origins of new gene function have been a subject of long-standing debate, Here we report a convincing case in which positive Darwinian selection operated at the molecular level during the evolution of novel function by gene duplication, The genes for eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) in primates belong to the ribonuclease gene family, and the ECP gene, whose product has an anti-pathogen function not displayed by EDN, was generated by duplication of the EDN gene about 31 million years ago, Using inferred nucleotide sequences of ancestral organisms, we showed that the rate of nonsynonymous nucleotide substitution was significantly higher than that of synonymous substitution for the ECP gene, This strongly suggests that positive Darwinian selection operated in the early stage of evolution of the ECP gene, It was also found that the number of arginine residues increased substantially in a short period of evolutionary time after gene duplication, and these amino acid changes probably produced the novel anti-pathogen function of ECP.