Increased polymerase fidelity of the 3TC-resistant variants of HIV-1 reverse transcriptase

• Published in: Nucleic acids research Vol. 25; no. 16; pp. 3212 - 3217
• Main Authors: Oude Essink, Belinda B., Back, Nicole K. T., Berkhout, Ben
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 15.08.1997
• Subjects: AIDS/HIV; DNA - metabolism; Drug Resistance; HIV Reverse Transcriptase - antagonists & inhibitors; HIV Reverse Transcriptase - genetics; HIV Reverse Transcriptase - metabolism; Lamivudine - pharmacology; Point Mutation; Recombinant Proteins; RNA - metabolism; Structure-Activity Relationship; Substrate Specificity; Templates, Genetic
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/25.16.3212

Human immunodeficiency virus type 1 (HIV-1) variants with resistance mutations in the reverse transcriptase (RT) gene appear during drug therapy with the nucleoside analogue 2′,3′-dideoxy-3′-thiacytidine (3TC). These 3TC-resistant RT variants have a single point mutation that changes the 184Met residue into either Val or Ile. Both codon 184 variants are frequently observed in 3TC-treated patients and can also be selected in cell culture infections. We demonstrated previously that the 184Ile and 184Val RT enzymes exhibit a processivity defect in in vitro assays, with 184Ile being the least processive enzyme [Met(wt) > Val > Ile]. In this study, we measured the polymerase fidelity of the wild-type (184Met) and 3TC-resistant RT enzymes (184Ile and 184Val) on DNA and RNA templates. Both virionextracted and Escherichia coli-expressed recombinant RT enzymes were used to measure the nucleotide misinsertion and mispair extension efficiencies. The 3TC-resistant enzymes were more accurate than the wild-type RT protein in both type of assays. The order of accuracy observed for the codon 184 variants [Ile > Val > Met(wt)] may suggest an inverse correlation between the fidelity and processivity properties of these enzymes.