title: Effects of HIV Q151M-associated multi-drug resistance mutations on the activities of (-)-beta-D-1',3'-dioxolan guanine.
abstract: The multi-drug resistance HIV-1 genotype A62V/V75I/F77L/F116Y/Q151M is associated with resistance to many nucleoside reverse transcriptase inhibitors including AZT, ddI, ddC, d4T, abacavir, and 3TC. In this study, we evaluated the antiviral activity of (-)-beta-D-1',3'-dioxolan guanine (DXG) towards mutant HIV-1 containing V75I/F77L/F116Y/Q151M (V75Icomplex) and A62V/V75I/F77L/F116Y/Q151M (A62Vcomplex) in MT-2 cells. We further investigated the mechanism of resistance by studying the incorporation of DXG 5'-triphosphate (DXG-TP) during DNA synthesis by mutant enzymes containing single mutations at Q151M or A62V, and the V75Icomplex and A62Vcomplex using pre-steady state kinetic analysis. Our studies showed that mutant virus containing V75Icomplex and A62Vcomplex were both more than 23-fold resistant to DXG, and this correlated with the 68- and 20-fold resistance changes observed in the enzymatic assay. Compared to the wild-type enzyme, DXG-TP was incorporated 39- and 21-fold less efficiently by the mutant enzyme containing V75Icomplex and A62Vcomplex, mainly due to decreases in the rate of incorporation. The A62V mutation significantly increased the rate of incorporation (k(pol)) for both dGTP (3-fold) and DXG-TP (7.9-fold), while the binding affinity of A62V HIV-1 RT for DXG-TP was decreased 14-fold. At the enzyme level, the addition of the A62V mutation to V75I/F77L/F116Y/Q151M moderately (3.4-fold) reversed the resistance to DXG-TP.
authors.affiliation: Gilead Science, 4 University Place, 4611 University Drive, Durham, NC 27707, USA. joy.feng@gilead.com
authors.forename: Joy Y
authors.initials: JY
authors.lastname: Feng
authors.forename: Florence
authors.initials: F
authors.lastname: Myrick
authors.forename: Boulbaba
authors.initials: B
authors.lastname: Selmi
authors.forename: Jérôme
authors.initials: J
authors.lastname: Deval
authors.forename: Bruno
authors.initials: B
authors.lastname: Canard
authors.forename: Katyna
authors.initials: K
authors.lastname: Borroto-Esoda
mesh_terms: D019943:Amino Acid Substitution; D004148:Dioxolanes / Q000737:chemistry / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D024882:Drug Resistance, Viral / Q000235:genetics; D005973:Glutamine / Q000235:genetics; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D006801:Humans; D008715:Methionine / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*
chemical_list: D004148:Dioxolanes; D018894:Reverse Transcriptase Inhibitors; C098394:dioxolane guanosine; D005973:Glutamine; D006151:Guanosine; D008715:Methionine; D054303:HIV Reverse Transcriptase