title: Role of a dipeptide insertion between codons 69 and 70 of HIV-1 reverse transcriptase in the mechanism of AZT resistance.
abstract: The 3'-azido-3'-deoxythymidine (AZT)-resistant pheno type of a heavily mutated human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) carrying a dipeptide (Ser-Ser) insertion between codons 69 and 70 as well as other mutations related to resistance to RT inhibitors has been studied. Recombinant virus carrying this variant RT (termed SS RT) showed reduced susceptibility to all nucleoside RT inhibitors in clinical use, particularly to AZT. In the presence of ATP, recombinant SS RT had an increased ability to remove the 3'-terminal nucleotide from AZT- terminated primers and extend the unblocked primer, compared with wild-type HIV-1 RT (BH10 isolate). Insertion of two serines in the sequence context of BH10 RT did not affect the ATP-dependent phosphorolytic activity of the enzyme, and had no influence in resistance to RT inhibitors. However, SS RT mutants lacking the dipeptide insertion or bearing a four-serine insertion showed reduced ATP-dependent phosphorolytic activity that correlated with increased AZT sensitivity, as determined using a recombinant virus assay. Therefore, the insertion appears to be critical to enhance AZT resistance in the sequence context of multidrug-resistant HIV-1 RT.
authors.affiliation: Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Mas
authors.forename: M
authors.initials: M
authors.lastname: Parera
authors.forename: C
authors.initials: C
authors.lastname: Briones
authors.forename: V
authors.initials: V
authors.lastname: Soriano
authors.forename: M A
authors.initials: MA
authors.lastname: Martínez
authors.forename: E
authors.initials: E
authors.lastname: Domingo
authors.forename: L
authors.initials: L
authors.lastname: Menéndez-Arias
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D014644:Genetic Variation; D054303:HIV Reverse Transcriptase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015497:HIV-1 / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D015215:Zidovudine / Q000494:pharmacology*
chemical_list: D003062:Codon; D017931:DNA Primers; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D054303:HIV Reverse Transcriptase