Coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases
Coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases
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DOI：
10.1017/s1355838201010251
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发表时间：
2001-08-01
期刊：
影响因子：
4.5
通讯作者：
Zimmerly, S
中科院分区：
文献类型：
--
作者：
Toor, N;Hausner, G;Zimmerly, S
催化RNA通常被认为是来自RNA世界的分子化石，但通常很难获得关于它们进化的更具体的信息。在这里，我们研究了第二组内含子RNA结构与其内含子编码的逆转录酶(RTS)的共同进化。与第一组内含子不同，内含子RNA结构和ORF之间没有明显的重新洗牌。在编码ORF的6类内含子结构中，有3类是传统形式的II A1、B1和B2类二级结构，其余的类是细菌类，可能与最原始的ORF有关，具有IIA和IIB组内含子结构的异常特征和杂交特征。基于这些数据，我们提出了一个新的第二组内含子进化模型，称为逆转录元件祖先假说，该模型预测第二组内含子的主要RNA结构形式是通过与内含子编码的蛋白质共同进化而形成的，而不是作为独立的催化RNA，并且大多数不含ORF的内含子是含有ORF的内含子的衍生子。该模型得到了含有和不含ORF内含子分布的支持，也得到了大量含有ORF残基的不含ORF内含子的例子的支持。
Catalytic RNAs are often regarded as molecular fossils from the RNA World, yet it is usually difficult to get more specific information about their evolution. Here we have investigated the coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases (RTs). Unlike group I introns, there has been no obvious reshuffling between intron RNA structures and ORFs. Of the six classes of intron structures that encode ORFs, three are conventional forms of group II A1, B1, and B2 secondary structures, whereas the remaining classes are bacterial, are possibly associated with the most primitive ORFs, and have unusual features and hybrid features of group IIA and group IIB intron structures. Based on these data, we propose a new model for the evolution of group II introns, designated the retroelement ancestor hypothesis, which predicts that the major RNA structural forms of group II introns developed through coevolution with the intron-encoded protein rather than as independent catalytic RNAs, and that most ORF-less introns are derivatives of ORF-containing introns. The model is supported by the distribution of ORF-containing and ORF-less introns, and by numerous examples of ORF-less introns that contain ORF remnants.