Characterization of novel non-nucleoside reverse transcriptase (RT) inhibitor resistance mutations at residues 132 and 135 in the 51 kDa subunit of HIV-1 RT

Dwight V. Nissley, Jessica Radzio, Zandrea Ambrose, Chih Wei Sheen, Noureddine Hamamouch, Katie L. Moore, Gilda Tachedjian, Nicolas Sluis-Cremer

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22 Scopus citations

Abstract

Several rare and novel NNRTI [non-nucleoside reverse transcriptase (RT) inhibitor] resistance mutations were recently detected at codons 132 and 135 in RTs from clinical isolates using the yeast-based chimaeric TyHRT (Ty1/HIV-1 RT) phenotypic assay. Ile132 and Ile135 form part of the β7-β8 loop of HIV-1 RT (residues 132-140). To elucidate the contribution of these residues in RT structure-function and drug resistance, we constructed twelve recombinant enzymes harbouring mutations at codons 132 and 135-140. Several of the mutant enzymes exhibited reduced DNA polymerase activities. Using the yeast two-hybrid assay for HIV-1 RT dimerization we show that in some instances this decrease in enzyme activity could be attributed to the mutations, in the context of the 51 kDa subunit of HIV-1 RT, disrupting the subunit-subunit interactions of the enzyme. Drug resistance analyses using purified RT, the TyHRT assay and antiviral assays demonstrated that the I132M mutation conferred high-level resistance (> 10-fold) to nevirapine and delavirdine and low-level resistance (∼2-3-fold) to efavirenz. The I135A and I135M mutations also conferred low level NNRTI resistance (∼2-fold). Subunit selective mutagenesis studies again demonstrated that resistance was conferred via the p51 subunit of HIV-1 RT. Taken together, our results highlight a specific role of residues 132 and 135 in NNRTI resistance and a general role for residues in the β7-β8 loop in the stability of HIV-1 RT.

Original languageEnglish (US)
Pages (from-to)151-157
Number of pages7
JournalBiochemical Journal
Volume404
Issue number1
DOIs
StatePublished - May 15 2007

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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