Pre-steady-state kinetic characterization of wild type and 3'-azido-3'-deoxythymidine (AZT) resistant human immunodeficiency virus type 1 reverse transcriptase: implication of RNA directed DNA polymerization in the mechanism of AZT resistance.

Important note: Information in this article was accurate in 1998. The state of the art may have changed since the publication date.

Biochemistry. 1997 Nov 18;36(46):14064-70. Unique Identifier : AIDSLINE MED/98039137
Kerr SG; Anderson KS; Department of Pharmacology, 333 Cedar Street, Yale University; School of Medicine, New Haven, Connecticut 06520-8066, USA.

Abstract: There is lack of a correlation between biochemical studies and the observed clinical resistance of AIDS patients on long term AZT therapy. Mutant HIV-1 reverse transcriptase in the viral isolates from these patients shows a 100-fold decrease in sensitivity whereas little or no difference is observed in kinetic parameters in vitro using steady-state kinetic analysis. A detailed pre-steady-state kinetic analysis of wild type and the clinically important AZT resistant mutant (D67N, K70R, T215Y, K219Q) HIV-1 reverse transcriptase was conducted to understand the mechanistic basis of drug resistance. In contrast to steady-state techniques, a pre-steady-state kinetic analysis allows for the direct observation of catalytic events occurring at the active site of the enzyme, including subtle conformational changes enabling a greater degree of mechanistic detail. In this investigation the rate of incorporation of dTMP and AZTMP by wild type and mutant HIV-1 RT was determined using an RNA and the corresponding DNA template. The present study has shown a 1.5-fold decrease in the rate constant for polymerization (kpol) and a 2.5-fold decrease in the equilibrium dissociation constant (Kd) for AZTTP for the mutant reverse transcriptase as compared to the wild type, for RNA dependent DNA replication. These values translate into a 4-fold decrease in selectivity (kpol/Kd) for AZTMP incorporation by mutant reverse transcriptase as compared to wild type for RNA dependent DNA replication. No such decrease in selectivity was detected for DNA dependent replication. These results suggest that the basis of AZT resistance is related to RNA dependent replication rather than DNA dependent replication.

Keywords: Anti-HIV Agents/*PHARMACOLOGY Comparative Study Drug Resistance HIV-1/*ENZYMOLOGY/GENETICS HIV-1 Reverse Transcriptase/*DRUG EFFECTS/GENETICS/METABOLISM Kinetics Mutation Reverse Transcriptase Inhibitors/*PHARMACOLOGY Ribonuclease H, Calf Thymus/ANALYSIS Support, U.S. Gov't, P.H.S. Thymidine Monophosphate/METABOLISM Thymine Nucleotides/METABOLISM Zidovudine/ANALOGS & DERIVATIVES/METABOLISM/*PHARMACOLOGY JOURNAL ARTICLE
980228
M9820703

AEGiS is a 501(c)3, not-for-profit, tax-exempt, educational corporation. AEGiS is made possible through unrestricted funding from Boehringer Ingelheim, Bridgestone/Firestone Charitable Trust, Bristol-Myers Squibb Company, Elton John AIDS Foundation, Gill Foundation, the National Library of Medicine, Quest Diagnostics, Roche and Trimeris, and donations from users like you. Always watch for outdated information. This article first appeared in 1998. This material is designed to support, not replace, the relationship that exists between you and your doctor.

AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.

Copyright ©1980, 1998. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content. .