Maintenance and Loss of Duplicated Genes by Dosage Subfunctionalization
Maintenance and Loss of Duplicated Genes by Dosage Subfunctionalization
复制标题
DOI：
10.1093/molbev/msv095
复制
发表时间：
2015-08-01
影响因子：
10.7
通讯作者：
Lynch, Michael
中科院分区：
文献类型：
--
作者：
Gout, Jean-Francois;Lynch, Michael
全基因组复制（WGD）在许多真核生物谱系中有助于基因库的富集。然而，大多数重复的基因最终都会丢失，目前还不清楚为什么一些重复的基因在进化上是成功的，而另一些则很快变成了假基因。在这里，我们表明，剂量的限制是反对后WGD基因丢失的几个草履虫物种，共享一个共同的祖先WGD的主要因素。我们提出了一个模型，其中大多数WGD衍生的重复保留其祖先功能，并保留产生足够的蛋白质执行相同的祖先功能。在这种模型下，单个重复基因的表达水平可以中性地进化，只要它们保持大致恒定的总表达，这允许随机遗传漂移，使两个拷贝对总表达的贡献不均匀。我们的分析表明，一旦达到高水平的不平衡，这可能需要相当长的时间，具有最低表达水平的拷贝贡献了总表达的足够小的部分，选择不再反对其损失。扩展我们的分析酵母物种共享一个共同的祖先WGD产生类似的结果，表明重复的基因保留剂量限制，其次是分歧的表达水平和最终的确定性基因丢失可能是一个普遍的特点后WGD进化。
Whole-genome duplications (WGDs) have contributed to gene-repertoire enrichment in many eukaryotic lineages. However, most duplicated genes are eventually lost and it is still unclear why some duplicated genes are evolutionary successful whereas others quickly turn to pseudogenes. Here, we show that dosage constraints are major factors opposing post-WGD gene loss in several Paramecium species that share a common ancestral WGD. We propose a model where a majority of WGD-derived duplicates preserve their ancestral function and are retained to produce enough of the proteins performing this same ancestral function. Under this model, the expression level of individual duplicated genes can evolve neutrally as long as they maintain a roughly constant summed expression, and this allows random genetic drift toward uneven contributions of the two copies to total expression. Our analysis suggests that once a high level of imbalance is reached, which can require substantial lengths of time, the copy with the lowest expression level contributes a small enough fraction of the total expression that selection no longer opposes its loss. Extension of our analysis to yeast species sharing a common ancestral WGD yields similar results, suggesting that duplicated-gene retention for dosage constraints followed by divergence in expression level and eventual deterministic gene loss might be a universal feature of post-WGD evolution.