Selective action of 4'-azidothymidine triphosphate on reverse transcriptase of human immunodeficiency virus type 1 and human DNA polymerases alpha and beta.
4'-Azidothymidine (ADRT) is a novel nucleoside analogue that exhibits potent inhibitory activity against the replication of human immunodeficiency virus (HIV) in lymphocytes. The mechanisms by which ADRT inhibits HIV reverse transcriptase (HIV-RT) as ADRT 5'-triphosphate (ADRT-TP), the active intracellular metabolite of ADRT, and as the ADRT-MP molecule incorporated into DNA were examined and compared to their effects on human DNA polymerases alpha and beta. Inhibition of HIV-RT by ADRT-TP is competitive against TTP and is more potent against RNA to DNA synthesis (Ki = 0.009 microM versus Km = 3.3 microM for TTP) than it is against DNA to DNA synthesis (Ki = 0.95 microM versus Km = 16.3 microM for TTP). ADRT-TP is also a more potent inhibitor for primer elongation on RNA template than on DNA template. ADRT-TP is a poor inhibitor of human DNA polymerases alpha (Ki = 62.5 microM) and beta (Ki = 150 microM) (Chen et al., 1992). The consequences of ADRT incorporation into DNA are strikingly different for the HIV-RT and for human DNA polymerases alpha and beta. DNA polymerases alpha and beta incorporate a single ADRT-MP molecule into nascent DNA at a very slow rate and continue to elongate. They are unable to incorporate a second consecutive ADRT-MP. However, HIV-RT is able to efficiently incorporate two consecutive ADRT molecules. Incorporation of two consecutive ADRT-MP molecules by HIV-RT prevents further DNA chain elongation. Incorporation of two ADRT-MP molecules separated by one deoxyribonucleoside monophosphate (dAMP, dCMP, or dGMP) also abolishes DNA chain elongation by HIV-RT.
Chen
M S
MS
Institute of Biochemistry and Cell Biology, Syntex Research, Palo Alto, California 94304.
Suttmann
R T
RT
Papp
E
E
Cannon
P D
PD
McRoberts
M J
MJ
Bach
C
C
Copeland
W C
WC
Wang
T S
TS
D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D002460:Cell Line; D004256:DNA Polymerase I / Q000037:antagonists & inhibitors*; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors*; D004261:DNA Replication / Q000187:drug effects; D004277:DNA, Single-Stranded / Q000378:metabolism; D054306:Dideoxynucleotides; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000201:enzymology*; D006801:Humans; D008969:Molecular Sequence Data; D018894:Reverse Transcriptase Inhibitors; D013698:Templates, Genetic; D015215:Zidovudine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000998:Antiviral Agents; D004277:DNA, Single-Stranded; D054306:Dideoxynucleotides; D018894:Reverse Transcriptase Inhibitors; C081566:4'-azidothymidine 5'-triphosphate; D015215:Zidovudine; D054303:HIV Reverse Transcriptase; D004256:DNA Polymerase I; D004257:DNA Polymerase II