cDNA-mediated Ty recombination can take place in the absence of plus-strand cDNA synthesis, but not in the absence of the integrase protein.

Ty elements belong to the family of LTR-containing retrotransposons. Ty RNA is reverse transcribed by Ty-encoded proteins. The cDNA then transposes to new locations in the genome by a process that involves the integrase protein encoded by the element. We have previously shown that the Ty cDNA molecule can participate in recombination events with genomic Tys. In this study we have analyzed the role of the integrase protein in cDNA-mediated Ty recombination. We found that this process involves the integrase protein in a temperature-dependent manner. In addition we have investigated whether double-stranded DNA is the only molecule that can participate in cDNA-mediated Ty recombination. We have shown that mutations in the polypurine tract that abolish plus-strand synthesis do not prevent cDNA-mediated recombination, implying that other types of intermediates from the reverse-transcription process (e.g. single-stranded DNA or a hybrid RNA-cDNA molecule) can participate in cDNA-mediated Ty recombination.