期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：23
页码：13207-13212
DOI：10.1073/pnas.231494498
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Group II introns, the presumed ancestors of nuclear pre-mRNA introns, are site-specific retroelements. In addition to "homing" to unoccupied sites in intronless alleles, group II introns transpose at low frequency to ectopic sites that resemble the normal homing site. Two general mechanisms have been proposed for group II intron transposition, one involving reverse splicing of the intron RNA directly into an ectopic DNA site, and the other involving reverse splicing into a site in RNA followed by reverse transcription and integration of the resulting cDNA by homologous recombination. Here, by using an "inverted-site" strategy, we show that the yeast mtDNA group II intron aI1 retrotransposes by reverse splicing directly into an ectopic DNA site. This same mechanism could account for other previously described ectopic transposition events in fungi and bacteria and may have contributed to the dispersal of group II introns into different genes.
