A novel mechanism of self-primed reverse transcription defines a new family of retroelements.
Retroviruses and long terminal repeat (LTR)-containing retrotransposons initiate reverse transcription by using a specific tRNA primer than anneals to the primer-binding site of the retroelement transcript. Sequences from a large number of retroviruses and LTR-containing retrotransposons had indicated that the role of tRNAs in priming reverse transcription is universal among these LTR-containing retroelements. Data presented here strongly support the surprising conclusion that Tf1, a highly active LTR-containing retrotransposon isolated from Schizosaccharomyces pombe, undergoes a novel self-priming process that requires hybridization between the primer-binding site and the first 11 bases of the Tf1 transcript. Single-base mutations in these regions block transposition and reverse transcription, while compensatory mutations that reestablish complementarily rescue both defects. In addition, the sequence of the minus-strand RNA primer of reverse transcription was consistent with its being derived from the 5' end of the Tf1 transcript. Evidence that this mechanism defines a new family of retroelements is presented.
Levin
H L
HL
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
D001483:Base Sequence; D008969:Molecular Sequence Data; D017354:Point Mutation; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D018626:Retroelements / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D018626:Retroelements