Selective action of 4'-azidothymidine triphosphate on reverse transcriptase of human immunodeficiency virus type 1 and human DNA polymerases alpha and beta

Biochemistry. 1993 Jun 15;32(23):6002-10. doi: 10.1021/bi00074a011.

Abstract

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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antiviral Agents / pharmacology*
  • Base Sequence
  • Cell Line
  • DNA Polymerase I / antagonists & inhibitors*
  • DNA Polymerase II / antagonists & inhibitors*
  • DNA Replication / drug effects
  • DNA, Single-Stranded / metabolism
  • Dideoxynucleotides
  • HIV Reverse Transcriptase
  • HIV-1 / enzymology*
  • Humans
  • Molecular Sequence Data
  • Reverse Transcriptase Inhibitors*
  • Templates, Genetic
  • Zidovudine / analogs & derivatives*
  • Zidovudine / pharmacology

Substances

  • Antiviral Agents
  • DNA, Single-Stranded
  • Dideoxynucleotides
  • Reverse Transcriptase Inhibitors
  • 4'-azidothymidine 5'-triphosphate
  • Zidovudine
  • HIV Reverse Transcriptase
  • DNA Polymerase I
  • DNA Polymerase II