title: Reduced dNTP interaction of human immunodeficiency virus type 1 reverse transcriptase promotes strand transfer.
abstract: We have recently demonstrated that HIV-1 RT mutants characterized by low dNTP binding affinity display significantly reduced dNTP incorporation kinetics in comparison to wild-type RT. This defect is particularly emphasized at low dNTP concentrations where WT RT remains capable of efficient synthesis. Kinetic interference in DNA synthesis can induce RT pausing and slow down the synthesis rate. RT stalling and slow synthesis rate can enhance RNA template cleavage by RT-RNase H, facilitating transfer of the primer to a homologous template. We therefore hypothesized that reduced dNTP binding RT mutants can promote template switching during minus strand synthesis more efficiently than WT HIV-1 RT at low dNTP concentrations. To test this hypothesis, we employed two dNTP binding HIV-1 RT mutants, Q151N and V148I. Indeed, as the dNTP concentration was decreased, the template switching frequency progressively increased for both WT and mutant RTs. However, as predicted, the RT mutants promoted more transfers compared with WT RT. The WT and mutant RTs were similar in their intrinsic RNase H activity, supporting that the elevated template switching efficiency of the mutants was not the result of the mutations enhancing RNase H activity. Rather, kinetic interference leading to stalled DNA synthesis likely enhanced transfers. These results suggest that the RT-dNTP substrate interaction mechanistically influences strand transfer and recombination of HIV-1 RT.
authors.affiliation: Departments of Microbiology and Immunology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Darwin J
authors.initials: DJ
authors.lastname: Operario
authors.forename: Mini
authors.initials: M
authors.lastname: Balakrishnan
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bambara
authors.forename: Baek
authors.initials: B
authors.lastname: Kim
mesh_terms: D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000096:biosynthesis / Q000737:chemistry*; D004279:DNA, Viral / Q000096:biosynthesis; D003854:Deoxyribonucleotides / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D015497:HIV-1 / Q000201:enzymology*; D006639:Histidine / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D009154:Mutation; D010957:Plasmids; D011485:Protein Binding / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism; D013698:Templates, Genetic
chemical_list: D004279:DNA, Viral; D003854:Deoxyribonucleotides; D006639:Histidine; D004247:DNA; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H