Origin and Evolution of the Eukaryotic SSU Processome Revealed by a Comprehensive Genomic Analysis and Implications for the Origin of the Nucleolus
Origin and Evolution of the Eukaryotic SSU Processome Revealed by a Comprehensive Genomic Analysis and Implications for the Origin of the Nucleolus
复制标题
综合基因组分析揭示真核 SSU 过程组的起源和进化以及对核仁起源的影响。
DOI：
10.1093/gbe/evt173
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发表时间：
2013-01-01
影响因子：
3.3
通讯作者：
Wen, Jian-Fan
中科院分区：
文献类型：
--
作者：
Feng, Jin-Mei;Tian, Hai-Feng;Wen, Jian-Fan
作为一种核仁复合物的小亚基（SSU）核糖体RNA加工，SSU加工体已被广泛研究，主要是在酿酒酵母，但不是在不同的生物，留下了开放的问题，它是否是一个普遍存在的机制，在真核生物的进化过程中，它是如何演变的。对SSU加工体组分的全基因组调查和鉴定表明，所有77种酵母SSU加工体蛋白中的大多数在几乎所有主要的真核谱系中都具有同源物，其中14种在古细菌中具有同源物，但在细菌中很少，这表明该复合物在真核生物中普遍存在，它的进化历史始于古生菌中存在丰富的蛋白质同系物，然后在最后一个真核生物共同祖先中出现了相当完整的复合体形式（LECA）。系统发育分析表明，在LECA从原核生物进化起源的过程中，古老的基因重复和复合体蛋白组分的功能分化频繁发生。我们发现，这种复制不仅增加了复合物的成分，但也产生了一些新的功能蛋白参与其他核仁的功能，如核糖体的生物合成，甚至一些非核仁（但核）蛋白参与前mRNA剪接，这意味着亚核区室-核仁的进化出现发生在LECA。因此，LECA不仅具有复杂的SSU过程体，而且还具有核仁。我们的分析还表明，在真核生物的分化过程中，基因的复制、创新和丢失导致了复合体的进一步分化。
As a nucleolar complex for small-subunit (SSU) ribosomal RNA processing, SSU processome has been extensively studied mainly in Saccharomyces cerevisiae but not in diverse organisms, leaving open the question of whether it is a ubiquitous mechanism across eukaryotes and how it evolved in the course of the evolution of eukaryotes. Genome-wide survey and identification of SSU processome components showed that the majority of all 77 yeast SSU processome proteins possess homologs in almost all of the main eukaryotic lineages, and 14 of them have homologs in archaea but few in bacteria, suggesting that the complex is ubiquitous in eukaryotes, and its evolutionary history began with abundant protein homologs being present in archaea and then a fairly complete form of the complex emerged in the last eukaryotic common ancestor (LECA). Phylogenetic analysis indicated that ancient gene duplication and functional divergence of the protein components of the complex occurred frequently during the evolutionary origin of the LECA from prokaryotes. We found that such duplications not only increased the complex's components but also produced some new functional proteins involved in other nucleolar functions, such as ribosome biogenesis and even some nonnucleolar (but nuclear) proteins participating in pre-mRNA splicing, implying the evolutionary emergence of the subnuclear compartment-the nucleolus-has occurred in the LECA. Therefore, the LECA harbored not only complicated SSU processomes but also a nucleolus. Our analysis also revealed that gene duplication, innovation, and loss, caused further divergence of the complex during the divergence of eukaryotes.