title: Restoration of the self-splicing activity of a defective group II intron by a small trans-acting RNA.
abstract: The yeast mitochondrial group II intron bI1 is self-splicing in vitro. We have introduced a deletion of hairpin C1 within the structural domain 1 that abolishes catalytic activity of the intron in the normal splicing reaction in cis, but does less severely affect a reaction in trans, the reopening of ligated exons. Since exon reopening is supposed to correspond to a reverse 3' cleavage this suggests that the deletion specifically blocks the first reaction step. The intron regains its activity to self-splice in cis by intermolecular complementation with a small RNA harbouring sequences lacking in the mutant intron. These results demonstrate the feasibility to reconstitute a functionally active structure of the truncated intron by intermolecular complementation in vitro. Furthermore, the data support the hypothesis that group II introns are predecessors of nuclear pre-mRNA introns and that the small nuclear RNAs of the spliceosome arose by segregation from the original intron.
authors.affiliation: Institut für Genetik und Mikrobiologie, Universität München, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Suchy
authors.forename: C
authors.initials: C
authors.lastname: Schmelzer
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D004252:DNA Mutational Analysis; D006860:Hydrogen Bonding; D007438:Introns; D008928:Mitochondria / Q000502:physiology*; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012331:RNA, Fungal / Q000502:physiology*; D012441:Saccharomyces cerevisiae; D013329:Structure-Activity Relationship
chemical_list: D012331:RNA, Fungal