Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Cold Spring Harb Perspect Biol. 2011 Aug 1;3(8):a003616. doi: 10.1101/cshperspect.a003616.
Group II introns are mobile ribozymes that self-splice from precursor RNAs to yield excised intron lariat RNAs, which then invade new genomic DNA sites by reverse splicing. The introns encode a reverse transcriptase that stabilizes the catalytically active RNA structure for forward and reverse splicing, and afterwards converts the integrated intron RNA back into DNA. The characteristics of group II introns suggest that they or their close relatives were evolutionary ancestors of spliceosomal introns, the spliceosome, and retrotransposons in eukaryotes. Further, their ribozyme-based DNA integration mechanism enabled the development of group II introns into gene targeting vectors ("targetrons"), which have the unique feature of readily programmable DNA target specificity.
内含子 II 是可移动的核酶，可从前体 RNA 中自我剪接，生成切除内含子套索 RNA，然后通过反向剪接侵入新的基因组 DNA 位点。这些内含子编码一种逆转录酶，可稳定催化活性 RNA 结构，以进行正向和反向剪接，然后将整合的内含子 RNA 转回 DNA。内含子 II 的特征表明，它们或它们的近亲是真核生物剪接体内含子、剪接体和反转录转座子的进化祖先。此外，它们基于核酶的 DNA 整合机制使内含子 II 发展成为基因靶向载体（“targetrons”），具有易于编程的 DNA 靶向特异性的独特特征。
