Increased polymerase fidelity of the 3TC-resistant variants of HIV-1 reverse transcriptase.
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 virion- extracted 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.
Oude Essink
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Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
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Berkhout
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D004247:DNA / Q000378:metabolism; D004351:Drug Resistance; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019259:Lamivudine / Q000494:pharmacology*; D017354:Point Mutation; D012313:RNA / Q000378:metabolism; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013698:Templates, Genetic
D011994:Recombinant Proteins; D019259:Lamivudine; D012313:RNA; D004247:DNA; D054303:HIV Reverse Transcriptase