Origin of new genes:: evidence from experimental and computational analyses
Origin of new genes:: evidence from experimental and computational analyses
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DOI：
10.1023/a:1024153609285
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发表时间：
2003-07-01
期刊：
影响因子：
1.5
通讯作者：
Zhang, JM
中科院分区：
文献类型：
--
作者：
Long, MY;Deutsch, M;Zhang, JM
外显子改组是形成新基因的重要分子机制。脊椎动物基因中已有许多外显子改组的报道。这些发现揭示了外显子改组在新基因起源中的重要性。然而，在植物和无脊椎动物中只有少数外显子改组的报道，这导致了内含子介导的重组机制起源于最近的断言。我们通过外显子改组和反向定位来研究新基因的起源。我们将首先总结我们的实验工作，在果蝇、植物和人类中发现了四个新基因。这些基因有1.06亿到1.08亿年的历史。这些基因的新近让我们可以直接详细地研究基因的起源和进化。这些观察结果首先表明了外显子改组和倒置在快速创建新基因结构中的重要性。他们还表明，以镶嵌蛋白或具有新调控系统的逆转录编码结构的形式出现的嵌合体结构通常赋予新的功能。此外，这些新产生的基因在整个历史上似乎一直受到达尔文式的积极选择的支配，在非常短的进化期内氨基酸序列和基因结构迅速变化。我们进一步分析了三个非脊椎动物物种，果蝇，秀丽线虫和拟南芥的内含子阶段的分布，从它们的基因组序列推断。与脊椎动物基因的情况一样，我们发现这些物种的内含子阶段分布不均匀，有大量的零相内含子和大量的对称外显子。这两个发现都与外显子洗牌的分子过程的要求一致。因此，一般而言，这些非脊椎动物基因组也可能受到外显子改组的强烈影响。
Exon shuffling is an essential molecular mechanism for the formation of new genes. Many cases of exon shuffling have been reported in vertebrate genes. These discoveries revealed the importance of exon shuffling in the origin of new genes. However, only a few cases of exon shuffling were reported from plants and invertebrates, which gave rise to the assertion that the intron-mediated recombination mechanism originated very recently. We focused on the origin of new genes by exon shuffling and retroposition. We will first summarize our experimental work, which revealed four new genes in Drosophila, plants, and humans. These genes are 106 to 108 million years old. The recency of these genes allows us to directly examine the origin and evolution of genes in detail. These observations show firstly the importance of exon shuffling and retroposition in the rapid creation of new gene structures. They also show that the resultant chimerical structures appearing as mosaic proteins or as retroposed coding structures with novel regulatory systems, often confer novel functions. Furthermore, these newly created genes appear to have been governed by positive Darwinian selection throughout their history, with rapid changes of amino acid sequence and gene structure in very short periods of evolution. We further analyzed the distribution of intron phases in three non-vertebrate species, Drosophila melanogaster, Caenorhabditis elegans, and Arabidosis thaliana, as inferred from their genome sequences. As in the case of vertebrate genes, we found that intron phases in these species are unevenly distributed with an excess of phase zero introns and a significant excess of symmetric exons. Both findings are consistent with the requirements for the molecular process of exon shuffling. Thus, these non-vertebrate genomes may have also been strongly impacted by exon shuffling in general.