Phase distribution of spliceosomal introns: implications for intron origin
Phase distribution of spliceosomal introns: implications for intron origin
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DOI：
10.1186/1471-2148-6-69
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发表时间：
2006-09-08
影响因子：
3.4
通讯作者：
Kenmochi, Naoya
中科院分区：
文献类型：
--
作者：
Nguyen, Hung D.;Yoshihama, Maki;Kenmochi, Naoya
背景：剪接体内含子的起源是内含子早期与内含子晚期争论的中心主题。内含子的相位分布不均匀，存在多余的0相内含子。内含子-早期解释了这一点，推测现在的一部分内含子存在于子代的小基因之间，因此一定处于0期。相反，内含子晚期预测了内含子相位分布的非均匀性反映了内含子插入的非随机性。结果：本文通过对内含子相分布的分析对这两种理论进行了验证。我们使用极大似然方法从7种真核生物的684个基因同源物数据集推断内含子相分布的进化。我们还测试了从10个真核生物中观察到的内含子相分布是否可以用全基因组范围内的内含子插入来解释。与内含子早期的预测相反，内含子期分布的推断进化表明，0期内含子的比例随着进化而增加。与内含子晚期相一致，观察到的内含子相位分布与内含子插入模型预测的相吻合。结论：本研究结果有力地支持了剪接体内含子起源的内含子晚发假说。
Background: The origin of spliceosomal introns is the central subject of the introns-early versus introns-late debate. The distribution of intron phases is non-uniform, with an excess of phase-0 introns. Introns-early explains this by speculating that a fraction of present-day introns were present between minigenes in the progenote and therefore must lie in phase-0. In contrast, introns-late predicts that the nonuniformity of intron phase distribution reflects the nonrandomness of intron insertions.Results: In this paper, we tested the two theories using analyses of intron phase distribution. We inferred the evolution of intron phase distribution from a dataset of 684 gene orthologs from seven eukaryotes using a maximum likelihood method. We also tested whether the observed intron phase distributions from 10 eukaryotes can be explained by intron insertions on a genome-wide scale. In contrast to the prediction of introns-early, the inferred evolution of intron phase distribution showed that the proportion of phase-0 introns increased over evolution. Consistent with introns-late, the observed intron phase distributions matched those predicted by an intron insertion model quite well.Conclusion: Our results strongly support the introns-late hypothesis of the origin of spliceosomal introns.