B. Berkhout et al., REQUIREMENTS FOR DNA STRAND TRANSFER DURING REVERSE TRANSCRIPTION IN MUTANT HIV-1 VIRIONS, Journal of Molecular Biology, 252(1), 1995, pp. 59-69
Retroviruses convert their RNA genome into a DNA form by means of reve
rse transcription. According to the current model of reverse transcrip
tion, two strand transfer reactions are needed to synthesize a full-le
ngth DNA genome. Because reverse transcription is initiated close to t
he 5' end of the RNA genome, the first strand transfer translocates th
e minus-strand cDNA to the 3' end of the viral genome. This jump is fa
cilitated by the presence of a perfect repeat element (R) at both ends
of a retroviral genome. Strand transfer has been extensively studied
in in vitro systems with purified reverse transcriptase enzyme (RT) an
d nucleic acid donor and acceptor templates. In this study, we set out
to test several parameters of the strand transfer reaction as it occu
rs in cells infected with the human immunodeficiency virus (HIV-I). We
constructed mutant HIV-1 genomes with 3' R acceptor sequences that we
re specifically altered either in length or structure. Analysis of the
replication characteristics of the mutant viruses indicates that repe
ats much shorter than the wild-type 97-nucleotides R region can effici
ently act as accepters during reverse transcription. Furthermore, the
introduction of excessively stable hairpin structures within the 3' R
element did only marginally affect the strand transfer efficiency. We
also analysed the DNA forms inherited upon infection of cells with HIV
-1 templates with multiple 3' R copies. These experiments indicate tha
t various 3' R repeats can serve as acceptor during minus-strand DNA t
ransfer. (C) 1995 Academic Press Limited