Selective action of 3'-azido-3'-deoxythymidine 5'-triphosphate on viral reverse transcriptases and human DNA polymerases.
The action of 3'-azido-3'-deoxythymidine 5'-triphosphate (N3dTTP) on DNA strand elongation catalyzed by human immunodeficiency virus type 1 reverse transcriptase was evaluated in comparison with human DNA polymerase alpha and proliferating cell nuclear antigen-independent DNA polymerase delta. Sequencing gel analysis demonstrated that the human immunodeficiency virus 1 reverse transcriptase preferentially incorporated N3dTTP into the T sites of the growing DNA strands and caused chain termination in a dose-dependent manner. This effect was observed even when the N3dTTP concentration was 0.3 microM, 100-fold less than dTTP. Studies with reverse transcriptases from avian myeloblastosis virus and Moloney murine leukemia virus showed that N3dTTP was also efficiently incorporated into DNA by these enzymes and terminated DNA strand elongation. In contrast, human DNA polymerases alpha and delta did not incorporate detectable amounts of N3dTTP into the DNA and were not inhibited by 300 microM N3dTTP. The selective incorporation of the chain-terminating nucleotide by the viral reverse transcriptases appears to be a molecular basis for the positive therapeutic index of 3'-azido-3'-deoxythymidine.
Huang
P
P
Department of Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
Farquhar
D
D
Plunkett
W
W
D000998:Antiviral Agents / Q000494:pharmacology*; D009189:Avian Myeloblastosis Virus / Q000201:enzymology; D001483:Base Sequence; D002460:Cell Line; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification; D054306:Dideoxynucleotides; D006678:HIV / Q000201:enzymology*; D006801:Humans; D008969:Molecular Sequence Data; D008979:Moloney murine leukemia virus / Q000201:enzymology; D019384:Nucleic Acid Synthesis Inhibitors; D015345:Oligonucleotide Probes; D018894:Reverse Transcriptase Inhibitors; D013379:Substrate Specificity; D013942:Thymine Nucleotides / Q000378:metabolism / Q000494:pharmacology*; D015215:Zidovudine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology
D000998:Antiviral Agents; D054306:Dideoxynucleotides; D019384:Nucleic Acid Synthesis Inhibitors; D015345:Oligonucleotide Probes; D018894:Reverse Transcriptase Inhibitors; D013942:Thymine Nucleotides; D015215:Zidovudine; C052873:zidovudine triphosphate; D004257:DNA Polymerase II; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase