Evolution of a large ribosomal RNA multigene family in filamentous fungi: Birth and death of a concerted evolution paradigm
Evolution of a large ribosomal RNA multigene family in filamentous fungi: Birth and death of a concerted evolution paradigm
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DOI：
10.1073/pnas.0409689102
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发表时间：
2005-04-05
影响因子：
11.1
通讯作者：
Ward, TJ
中科院分区：
文献类型：
--
作者：
Rooney, AP;Ward, TJ
在真核生物中，核糖体的主要成分由多拷贝核核糖体RNA（rRNA）基因编码：28/26 S、18 S、5.8S和5S。这些基因的拷贝通常位于串联阵列内并在基因组内均质化。因此，核rRNA基因家族已成为协同进化的范式。在盘菌亚门的丝状真菌中，5S rRNA基因作为一个大而分散的多基因家族存在，每个基因组有50至100个拷贝。为了确定这些基因是否违背协同进化范式，我们通过使用四个物种的完整基因组序列来研究这些基因的进化模式。对这些序列的分析揭示了（i）基因组内的多个5S基因类型，（h）基因类型的种间聚类，（f）种间共享的多个相同基因类型，（iv）基因组内的多个假基因，以及（v）在密切相关物种的比较中存在/不存在个体55个拷贝的变异。这些结果表明，在这些物种的5S家族的出生和死亡的进化特征下，强烈的净化选择。此外，我们的研究结果表明，出生和死亡的进化发生在不同的速度在属检查，并在整个基因组的5S基因的增殖和运动是高度动态的。因此，我们假设一种类似于逆转录的机制控制着SS rRNA基因在丝状真菌基因组中的扩增、扩散和整合。
In eukaryotes, the primary components of the ribosome are encoded by multicopy nuclear ribosomal RNA (rRNA) genes: 28/26S, 18S, 5.8S, and 5S. Copies of these genes are typically localized within tandem arrays and homogenized within a genome. As a result, nuclear rRNA gene families have become a paradigm of concerted evolution. In filamentous fungi of the subphylum Pezizomycotina, 5S rRNA genes exist as a large and dispersed multigene family, with between 50 and 100 copies per genome. To determine whether these genes defy the concerted evolution paradigm, we examined the patterns of evolution of these genes by using sequences from the complete genomes of four species. Analyses of these sequences revealed (i) multiple 5S gene types within a genome, (h) interspecies clustering of gene types, (fil) multiple identical gene types shared among species, (iv) multiple pseudogenes within a genome, and (v) presence/absence variation of individual 55 copies in comparisons of closely related species. These results demonstrate that the 5S family in these species is characterized by birth-and-death evolution under strong purifying selection. Furthermore, our results suggest that birth-and-death evolution occurs at different rates in the genera examined, and that the multiplication and movement of 5S genes across the genome are highly dynamic. As such, we hypothesize that a mechanism resembling retroposition controls SS rRNA gene amplification, dispersal, and integration in the genomes of filamentous fungi.