title: Reverse transcriptase activity of an intron encoded polypeptide.
abstract: A number of group II introns from eukaryotic organelles and prokaryotes contain open reading frames for polypeptides with homology to retroviral reverse transcriptases (RTs). We have used the yeast transposon (Ty) system to express ORFs for RTs from eukaryotic organelles. This includes the mitochondrial coxI intron i1 from the fungus Podospora anserina, the plastid petD intron from the alga Scenedesmus obliquus and the mitochondrial RTL gene from the alga Chlamydomonas reinhardtii. The ORFs were fused with the TYA ORF from the yeast retrotransposon Ty to produce virus-like particles in the recipient strains with detectable amounts of the RT-like polypeptides. Analysis of the heterologous gene products revealed biochemical evidence that the P. anserina intron encodes an RNA-directed DNA polymerase with properties typically found for RTs of viral or retrotransposable origin. In vitro assays showed that the intron encoded RT is sensitive to RT inhibitors such as N-ethylmaleimide and dideoxythymidine triphosphate but is insensitive against the DNA polymerase inhibitor aphidicolin. The direct biochemical evidence provided here supports the idea that intron encoded RTs are involved in intron transposition events.
authors.affiliation: Lehrstuhl für Allgemeine Botanik, Ruhr-Universität Bochum, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Fassbender
authors.forename: K H
authors.initials: KH
authors.lastname: Brühl
authors.forename: M
authors.initials: M
authors.lastname: Ciriacy
authors.forename: U
authors.initials: U
authors.lastname: Kück
mesh_terms: D001203:Ascomycota / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D004271:DNA, Fungal; D056890:Eukaryota / Q000235:genetics; D005815:Genetic Code; D007438:Introns; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D004271:DNA, Fungal; D010455:Peptides; D011993:Recombinant Fusion Proteins; D012194:RNA-Directed DNA Polymerase