title: The valine-to-threonine 75 substitution in human immunodeficiency virus type 1 reverse transcriptase and its relation with stavudine resistance.
abstract: The amino acid change V75T in human immunodeficiency virus type 1 reverse transcriptase confers a low level of 2',3'-didehydro-2',3'-dideoxythymidine (stavudine, d4T) resistance in vivo and in vitro. Valine 75 is located at the basis of the fingers subdomain of reverse transcriptase between the template contact point and the nucleotide-binding pocket. V75T reverse transcriptase discriminates 3.6-fold d4T 5'-triphosphate relative to dTTP, as judged by pre-steady state kinetics of incorporation of a single nucleotide into DNA. In addition, V75T increases the DNA polymerization rate up to 5-fold by facilitating translocation along nucleic acid single-stranded templates. V75T also increases the reverse transcriptase-mediated repair of the d4TMP-terminated DNA by pyrophosphate but not by ATP. The V75T/Y146F double substitution partially suppressed both increases in rate of polymerization and pyrophosphorolysis, indicating that the hydroxyl group of Thr-75 interacts with that of Tyr-146. V75T recombinant virus was 3-4-fold d4T-resistant and 3-fold resistant to phosphonoformic acid relative to wild type, confirming that the pyrophosphate traffic is affected in V75T reverse transcriptase. Thus, in addition to nucleotide selectivity V75T defines a type of amino acid change conferring resistance to nucleoside analogues that links translocation rate to the traffic of pyrophosphate at the reverse transcriptase active site.
authors.affiliation: CNRS and Universités d'Aix-Marseille I and II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, ESIL-Case 925, 13288 Marseille Cedex 9, France.
authors.forename: B
authors.initials: B
authors.lastname: Selmi
authors.forename: J
authors.initials: J
authors.lastname: Boretto
authors.forename: J M
authors.initials: JM
authors.lastname: Navarro
authors.forename: J
authors.initials: J
authors.lastname: Sire
authors.forename: S
authors.initials: S
authors.lastname: Longhi
authors.forename: C
authors.initials: C
authors.lastname: Guerreiro
authors.forename: L
authors.initials: L
authors.lastname: Mulard
authors.forename: S
authors.initials: S
authors.lastname: Sarfati
authors.forename: B
authors.initials: B
authors.lastname: Canard
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019380:Anti-HIV Agents / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology; D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000737:chemistry; D004260:DNA Repair / Q000187:drug effects; D004351:Drug Resistance; D054303:HIV Reverse Transcriptase / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008958:Models, Molecular; D010957:Plasmids / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D018119:Stavudine / Q000494:pharmacology*; D013912:Threonine / Q000737:chemistry*; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry; D014633:Valine / Q000737:chemistry*; D015215:Zidovudine / Q000494:pharmacology
chemical_list: D019380:Anti-HIV Agents; D000998:Antiviral Agents; D011994:Recombinant Proteins; D013912:Threonine; D014443:Tyrosine; D015215:Zidovudine; D000255:Adenosine Triphosphate; D004247:DNA; D018119:Stavudine; D054303:HIV Reverse Transcriptase; D014633:Valine