title: Mobility of yeast mitochondrial group II introns: engineering a new site specificity and retrohoming via full reverse splicing.
abstract: The mobile group II introns aI1 and aI2 of yeast mtDNA encode endonuclease activities that cleave intronless DNA target sites to initiate mobility by target DNA-primed reverse transcription. For aI2, sense-strand cleavage occurs mainly by a partial reverse splicing reaction, whereas for aI1, complete reverse splicing occurs, leading to insertion of the linear intron RNA into double-stranded DNA. Here, we show that aI1 homing and reverse splicing depend on the EBS1 (RNA)/IBS1(DNA) pairing and that target specificity can be changed by compensatory changes in the target site and the donor intron. Using well-marked strains to follow coconversion of flanking DNA, we show that homing occurs by both RT-dependent and -independent pathways. Remarkably, in most RT-dependent events, the reverse spliced intron is the initial template for first-strand cDNA synthesis.
authors.affiliation: Department of Molecular Biology and Oncology, University of Texas Southwestern Medical Center, Dallas 75235-9148, USA.
authors.forename: R
authors.initials: R
authors.lastname: Eskes
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: A M
authors.initials: AM
authors.lastname: Lambowitz
authors.forename: P S
authors.initials: PS
authors.lastname: Perlman
mesh_terms: D001483:Base Sequence; D018076:DNA, Complementary / Q000032:analysis / Q000138:chemical synthesis; D004271:DNA, Fungal / Q000032:analysis; D004272:DNA, Mitochondrial / Q000502:physiology*; D004720:Endonucleases / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D007438:Introns / Q000235:genetics*; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D010957:Plasmids; D012326:RNA Splicing / Q000235:genetics; D011995:Recombination, Genetic; D015003:Yeasts / Q000201:enzymology / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D004720:Endonucleases