Recurrent tandem gene duplication gave rise to functionally divergent genes in Drosophila
Recurrent tandem gene duplication gave rise to functionally divergent genes in Drosophila
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DOI：
10.1093/molbev/msn089
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发表时间：
2008-07-01
影响因子：
10.7
通讯作者：
Long, Manyuan
中科院分区：
文献类型：
--
作者：
Fan, Chuanzhu;Chen, Ying;Long, Manyuan
串联基因复制是真核生物中主要的基因复制机制之一，基因家族集群的普遍存在说明了这一点。串联重复的类似物通常具有相同的调控元件，因此它们可能具有相似的生物学功能。在这里，我们提供了一个新进化的串联重复获得新功能的例子，这是由正选择驱动的。CG32708、CG32706和CG6999是存在于果蝇X染色体上的3个聚类基因。研究了CG6999和CG32708的分子群体遗传特性（Thornton and Long 2005）。我们进一步研究了作用于这些基因的进化力量，使用了更大的样本量和更广泛的方法，包括物种间的差异，使用了更多种类的统计方法。我们通过表征这些基因的组织特异性和发育表达模式来探索可能的功能含义。对黑腹龙亚群各物种的序列比较表明，这一3基因簇是在近5myr内由2轮串联基因重复形成的。系统发育分析表明，CG32708是所有物种共有的亲本拷贝。CG32706可能起源于5亿年前拟果蝇和D. melanogaster的祖先，而CG6999是D. melanogaster所独有的最新副本。这3个基因都有不同的表达谱，CG6999也获得了一个新的转录本。偏态多态性频谱分析、连锁不平衡分析、核苷酸替代分析和McDonald-Kreitman分析表明，CG6999和CG32706的进化是由达尔文正选择驱动的。
Tandem gene duplication is one of the major gene duplication mechanisms in eukaryotes, as illustrated by the prevalence of gene family clusters. Tandem duplicated paralogs usually share the same regulatory element, and as a consequence, they are likely to perform similar biological functions. Here, we provide an example of a newly evolved tandem duplicate acquiring novel functions, which were driven by positive selection. CG32708, CG32706, and CG6999 are 3 clustered genes residing in the X chromosome of Drosophila melanogaster. CG6999 and CG32708 have been examined for their molecular population genetic properties (Thornton and Long 2005). We further investigated the evolutionary forces acting on these genes with greater sample sizes and a broader approach that incorporate between-species divergence, using more variety of statistical methods. We explored the possible functional implications by characterizing the tissue-specific and developmental expression patterns of these genes. Sequence comparison of species within D. melanogaster subgroup reveals that this 3-gene cluster was created by 2 rounds of tandem gene duplication in the last 5 Myr. Based on phylogenetic analysis, CG32708 is clearly the parental copy that is shared by all species. CG32706 appears to have originated in the ancestor of Drosophila simulans and D. melanogaster about 5 Mya, and CG6999 is the newest duplicate that is unique to D. melanogaster. All 3 genes have different expression profiles, and CG6999 has in addition acquired a novel transcript. Biased polymorphism frequency spectrum, linkage disequilibrium, nucleotide substitution, and McDonald-Kreitman analyses suggested that the evolution of CG6999 and CG32706 were driven by positive Darwinian selection.