title: A novel reverse transcriptase activity associated with mitochondrial plasmids of Neurospora.
abstract: The Mauriceville and Varkud mitochondrial plasmids of Neurospora are closely related DNA elements whose nucleotide sequences and genetic organization suggest relationships to retrotransposons and mitochondrial introns. Both plasmids potentially encode a reverse transcriptase-like protein of 710 amino acids. We show that mitochondria from the Mauriceville and Varkud strains contain a reverse transcriptase activity highly specific for endogeneous plasmid RNA in RNP preparations. The reverse transcriptase synthesizes full-length minus-strand DNA beginning at the 3' end of the plasmid transcript, which has tRNA-like characteristics similar to the 3' ends of plant viral RNAs. Our results suggest that the plasmids use a novel mechanism of reverse transcription, which may have evolved to utilize tRNA-like structures at the 3' ends of self-replicating RNAs. This mechanism may be ancestral to the standard retroviral mechanism.
authors: Department of Molecular Genetics, Ohio State University, Columbus 43210.
authors: M T
authors: MT
authors: Kuiper
authors: A M
authors: AM
authors: Lambowitz
mesh_terms: D004251:DNA Transposable Elements; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism; D007438:Introns; D007700:Kinetics; D009491:Neurospora / Q000201:enzymology* / Q000235:genetics; D009690:Nucleic Acid Conformation; D010957:Plasmids; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D015719:Single-Strand Specific DNA and RNA Endonucleases
chemical_list: D004251:DNA Transposable Elements; D004272:DNA, Mitochondrial; D012194:RNA-Directed DNA Polymerase; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases