Human immunodeficiency virus type 2 reverse transcriptase activity in model systems that mimic steps in reverse transcription.
Human immunodeficiency virus type 2 (HIV-2) infection is a serious problem in West Africa and Asia. However, there have been relatively few studies of HIV-2 reverse transcriptase (RT), a potential target for antiviral therapy. Detailed knowledge of HIV-2 RT activities is critical for development of specific high-throughput screening assays of potential inhibitors. Here, we have conducted a systematic evaluation of HIV-2 RT function, using assays that model specific steps in reverse transcription. Parallel studies were performed with HIV-1 RT. In general, under standard assay conditions, the polymerase and RNase H activities of the two enzymes were comparable. However, when the RT concentration was significantly reduced, HIV-2 RT was less active than the HIV-1 enzyme. HIV-2 RT was also impaired in its ability to catalyze secondary RNase H cleavage in assays that mimic tRNA primer removal during plus-strand transfer and degradation of genomic RNA fragments during minus-strand DNA synthesis. In addition, initiation of plus-strand DNA synthesis was much less efficient with HIV-2 RT than with HIV-1 RT. This may reflect architectural differences in the primer grip regions in the p66 (HIV-1) and p68 (HIV-2) palm subdomains of the two enzymes. The implications of our findings for antiviral therapy are discussed.
Post
Klara
K
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
Guo
Jianhui
J
Howard
Kathryn J
KJ
Powell
Michael D
MD
Miller
Jennifer T
JT
Hizi
Amnon
A
Le Grice
Stuart F J
SF
Levin
Judith G
JG
D001483:Base Sequence; D017931:DNA Primers; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis; D054303:HIV Reverse Transcriptase; D015498:HIV-2 / Q000201:enzymology* / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D016914:Ribonuclease H / Q000378:metabolism; D014158:Transcription, Genetic
D017931:DNA Primers; D004279:DNA, Viral; C072416:reverse transcriptase, Human immunodeficiency virus 2; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H