Reverse transcriptase activity associated with maturase-encoding group II introns in yeast mitochondria.
Group II introns al1 and al2 of the yeast mtDNA cox1 gene encode reverse transcriptase-like proteins that function in RNA splicing and may play a role in intron mobility and excision. We find that ribonucleoprotein particles from yeast mitochondria contain a reverse transcriptase activity that is likely encoded by al1 and al2 and is highly specific for the introns and their flanking exons. Using a mutant strain with elevated activity, we show that the reverse transcriptase uses either excised intron RNA or cox1 pre-mRNA as template and initiates cDNA synthesis near the 3' end of al2 and immediately downstream in E3. Our results suggest that introns al1 and al2 are retroelements, which encode reverse transcriptases that have adapted to function in RNA splicing.
Kennell
J C
JC
Department of Molecular Genetics, Ohio State University, Columbus 43210-1292.
Moran
J V
JV
Perlman
P S
PS
Butow
R A
RA
Lambowitz
A M
AM
D001483:Base Sequence; D004251:DNA Transposable Elements; D005091:Exons / Q000235:genetics; D007438:Introns / Q000235:genetics*; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012194:RNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D012261:Ribonucleoproteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic
D004251:DNA Transposable Elements; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C066564:aI2 protein, S cerevisiae; D012194:RNA-Directed DNA Polymerase