Properties of the reverse transcription of synthetic and hamster retroviral RNA by avian and hamster viral polymerases

Reverse transcription of poly(rA)·oligo(dT) and of the viral RNA present in purified virions of a hamster retrovirus by hamster and avian reverse transcriptase has been examined under various reaction conditions. The results demonstrate that the hamster virus polymerase transcribes by a processive mechanaism and that the size of the poly(dT) transcripts is not influenced by dTTP or enzyme concentrations. These and previous results show that initiation is the rate-limiting step. Both polymerases were markedly more active with Mn²⁺ than Mg²⁺ when tested on the hamster viral RNA template and produced the same "strong stop" cDNA with either metal ion. Evidence is presented which suggests that the metal ions affect the template activity of the polyribonucleic acids rather than the activity of the enzyme.