DNA chain termination activity and inhibition of human immunodeficiency virus reverse transcriptase by carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine triphosphate.
Carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine (carbovir, NSC 614846) is an anti-retroviral agent that may be useful in the treatment of AIDS. We have examined the ability of (-)-enantiomeric carbovir triphosphate to inhibit human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (EC 2.7.7.49). A comparison of inhibition kinetics was made with 3'-azido-2',3'-dideoxythymidine triphosphate and phosphonoformate. Inhibition of the reverse transcriptase was evaluated using poly(rA).oligo(dT)12-18, poly(rC).oligo(dG)12-18, or influenza virion RNA template with a specific oligodeoxynucleotide as primer. (-)-Carbovir 5'-triphosphate was shown to be a potent inhibitor of HIV-1 reverse transcriptase with an apparent Ki similar to that of 3'-azido-2',3'-dideoxythymidine triphosphate. Chain elongation studies utilizing an MS2 RNA template showed that (-)-carbovir 5'-triphosphate terminated transcription at positions identical to those where dideoxy-GTP terminated. This indicates that (-)-carbovir 5'-monophosphate is incorporated into the newly synthesized DNA and terminates transcription at that point. We conclude that (-)-carbovir 5'-triphosphate is a potent inhibitor of the HIV-1 reverse transcriptase enzyme and that (-)-carbovir most likely inhibits HIV by activity at the triphosphate level by a combination of direct competition for binding of the natural deoxynucleoside triphosphates to the reverse transcriptase and chain termination.
Department of Virology, Glaxo Group Research Ltd., Greenford, United Kingdom.
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Penn
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Cameron
D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D004279:DNA, Viral / Q000187:drug effects* / Q000235:genetics; D015224:Dideoxynucleosides / Q000494:pharmacology*; D004926:Escherichia coli / Q000378:metabolism; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology; D007700:Kinetics; D008969:Molecular Sequence Data; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors; D014158:Transcription, Genetic / Q000187:drug effects*; D015215:Zidovudine / Q000494:pharmacology
D000998:Antiviral Agents; D004279:DNA, Viral; D015224:Dideoxynucleosides; D018894:Reverse Transcriptase Inhibitors; C057503:carbovir; D015215:Zidovudine; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase