Initiation of in vitro reverse transcription from tRNALys3 on HIV-1 HIV-2 RNAs by both type 1 and 2 reverse transcriptases

HIV reverse transcription is initiated from a cellular tRNA partially associated,vith the retroviral genome. Here we studied homologous HIV-2 cDNa synthesis using natural or synthetic primers, With natural tRNA(Lys3), synthesis of early products comprising nucleotides +5 to +7 preceded the elongation step leading to synthesis of (-) strong-stop cDNA, In the presence of a poly(A)-oligo(dT) trap, no full-length product was observed while early products were still present, showing a transition between initiation and elongation. With DNA primers only an unspecific elongation was found. Our data show a similar mechanism of reverse transcription initiation by HIV-1 and HIV-2 reverse transcriptases. Furthermore, using a heterologous system we found that HIV-I RNA, in contrast to data reported in the literature, was an excellent template for HIV-2 reverse transcriptase. (C) 1998 Federation of European Biochemical Societies.