Complex spliceosomal organization ancestral to extant eukaryotes
Complex spliceosomal organization ancestral to extant eukaryotes
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DOI：
10.1093/molbev/msi091
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发表时间：
2005-04-01
影响因子：
10.7
通讯作者：
Penny, D
中科院分区：
文献类型：
--
作者：
Collins, L;Penny, D
在高等真核生物中，内含子被剪接体从编码蛋白质的mRNA中剪接出来，剪接体是一种包含5个非编码RNA（ncRNA）和约200个蛋白质的巨大复合物。通过比较剪接体蛋白质之间的差异，从许多基础真核细胞谱系，它是可能的，以推断在现存的真核生物的最后共同祖先，真核祖先的剪接系统的属性。我们开始的假设是，类似于内含子长度（在多细胞真核生物中似乎已经增加），剪接体的复杂性在整个真核生物进化过程中增加。然而，剪接体成分的分布研究表明，剪接体不仅存在于真核生物的祖先，而且它还包含了在今天的真核生物中发现的大多数关键成分。所有的小核核糖核蛋白（snRNP）的蛋白质成分可能已经存在，以及许多剪接相关的蛋白质。主要剪接和反式剪接都可能存在，剪接体已经与其他细胞过程如转录和加帽形成了联系。然而，目前还没有证据表明真核生物的祖先中存在微小的（U12依赖的）剪接。尽管现存真核生物的最后一个共同祖先似乎表现出了今天所见的分子复杂性，但我们不能从这项工作中推断出早期“第一个真核生物”的任何特性。"
In higher eukaryotes, introns are spliced out of protein-coding mRNAs by the spliceosome, a massive complex comprising five non-coding RNAs (ncRNAs) and about 200 proteins. By comparing the differences between spliceosomal proteins from many basal eukaryotic lineages, it is possible to infer properties of the splicing system in the last common ancestor of extant eukaryotes, the eukaryotic ancestor. We begin with the hypothesis that, similar to intron length (that appears to have increased in multicellular eukaryotes), the spliceosome has increased in complexity throughout eukaryotic evolution.However, examination of the distribution of spliceosomal components indicates that not only was a spliceosome present in the eukaryotic ancestor but it also contained most of the key components found in today's eukaryotes. All the small nuclear ribonucleoproteins (snRNPs) protein components are likely to have been present, as well as many splicing-related proteins. Both major and trans-splicing are likely to have been present, and the spliceosome had already formed links with other cellular processes such as transcription and capping. However, there is no evidence as yet to suggest that minor (U12-dependent) splicing was present in the eukaryotic ancestor.Although the last common ancestor of extant eukaryotes appears to show much of the molecular complexity seen today, we do not, from this work, infer anything of the properties of the earlier "first eukaryote."