An early evolutionary origin for the minor spliceosome
An early evolutionary origin for the minor spliceosome
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DOI：
10.1038/nature05228
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发表时间：
2006-10-19
期刊：
影响因子：
64.8
通讯作者：
Gray, Michael W.
中科院分区：
文献类型：
--
作者：
Russell, Anthony G.;Charette, J. Michael;Gray, Michael W.
次要剪接体是一种核糖核蛋白复合物，催化从真核信使RNA中去除非典型剪接体内含子（U12型）1，2。它首先在动物中被鉴定和表征，发现它含有几种独特的RNA成分，这些成分与主要剪接体中包含的小核RNA（snRNA）具有结构相似性，并且似乎在功能上类似（3-8）。随后，在植物中发现了少量剪接体组分和U12型内含子（9-12），但在真菌中未发现。与在真核生物谱系早期出现的主要剪接体不同（13，14），次要剪接体的进化历史尚不清楚，因为在很少的生物中有证据表明它。在这里，我们报告的同源物的小剪接体特异性蛋白质和snRNAs，和U12型内含子，在远亲的真核微生物（原生生物）和真菌（根霉）的鉴定。累积起来，我们的研究结果表明，小剪接体有一个早期的起源：它的几个特征成分存在于所有真核生物超组的代表性生物体中，有任何实质性的基因组序列信息。此外，我们的研究结果揭示了U12型内含子和snRNA中包含的功能重要的序列元件的显着进化保守性。
The minor spliceosome is a ribonucleoprotein complex that catalyses the removal of an atypical class of spliceosomal introns (U12-type) from eukaryotic messenger RNAs1,2. It was first identified and characterized in animals, where it was found to contain several unique RNA constituents that share structural similarity with and seem to be functionally analogous to the small nuclear RNAs (snRNAs) contained in the major spliceosome(3-8). Subsequently, minor spliceosomal components and U12-type introns have been found in plants(9-12) but not in fungi. Unlike that of the major spliceosome, which arose early in the eukaryotic lineage(13,14), the evolutionary history of the minor spliceosome is unclear because there is evidence of it in so few organisms. Here we report the identification of homologues of minor-spliceosome-specific proteins and snRNAs, and U12-type introns, in distantly related eukaryotic microbes (protists) and in a fungus ( Rhizopus oryzae). Cumulatively, our results indicate that the minor spliceosome had an early origin: several of its characteristic constituents are present in representative organisms from all eukaryotic supergroups for which there is any substantial genome sequence information. In addition, our results reveal marked evolutionary conservation of functionally important sequence elements contained within U12-type introns and snRNAs.