Coupling of reverse transcriptase and RNase H during HIV-1 replication.
The retroviral replicating enzyme reverse transcriptase (RT) is associated with an RNase H which specifically hydrolyzes RNA in RNA-DNA hybrids. The RNase H exhibits endo- as well as exonuclease activity when analyzed with in vitro synthesized viral RNA hybridized to a shorter synthetic DNA oligonucleotide. In the presence of deoxyribonucleotides the RT synthesizes DNA in a concerted action with the RNase H, which simultaneously hydrolyzes the RNA template. Mutants of the RNase H derived by site-directed mutagenesis of a conserved histidine 539 are preferentially impaired in their exo- and less in their endonuclease activity. A specific polypurine-rich oligonucleotide created at the polypurine tract (PPT), serves as a primer for plus-strand DNA synthesis. Initiation of DNA synthesis at the PPT-primer can be demonstrated for the wt enzyme in vitro in contrast to the mt enzymes which do not recognize this sequence. A replication model based on these results is presented.
Wöhrl
B M
BM
Max-Planck-Institut für Molekulare Genetik, Abt. Schuster, Germany.
Moelling
K
K
D001483:Base Sequence; D004261:DNA Replication; D015497:HIV-1 / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009843:Oligoribonucleotides; D012367:RNA, Viral / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016914:Ribonuclease H / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014779:Virus Replication
D009843:Oligoribonucleotides; D012367:RNA, Viral; D011994:Recombinant Proteins; D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H