title: Susceptibility of feline immunodeficiency virus/human immunodeficiency virus type 1 reverse transcriptase chimeras to non-nucleoside RT inhibitors.
abstract: To map the determinants of the lack of susceptibility of feline immunodeficiency virus (FIV) reverse transcriptase (RT) to anti human immunodeficiency virus type 1 (HIV-1) non-nucleoside RT inhibitors (NNRTIs), a variety of chimeric HIV-1/FIV RTs were constructed. The majority of chimeric RTs had an affinity (Km) for their natural substrates comparable with that of the wild-type HIV-1 and FIV RTs, but their catalytic efficacy was decreased. Whereas HIV-1 RT could be made entirely insensitive to NNRTIs by exchanging the amino acid sequence 97 through 205 of FIV RT, none of the reverse FIV/HIV-1 RT chimeras gained susceptibility to NNRTIs. The amino acids that are thought to be involved in NNRTI susceptibility and that are different from those in HIV-1 RT have also been introduced in FIV RT. These mutant RTs gained virtually no susceptibility to efavirenz or capravirine. Vice versa, when these HIV-1-specific amino acids were replaced by their FIV RT counterparts in HIV-1 RT, susceptibility to the NNRTIs was lost. Thus, replacing segments or substituting relevant amino acids in FIV RT by their HIV-1 RT counterparts did not suffice to make FIV RT sensitive toward NNRTIs and was often accompanied by a decrease or even total loss of polymerase activity. It is postulated that, in contrast to the results found for HIV-1/HIV-2 RT chimeras and supported by the crystal structure of HIV-2 RT, there exist significant differences in the structure and/or flexibility of FIV RTs that may prevent NNRTIs from interacting with the FIV RT.
authors.affiliation: Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Joeri
authors.initials: J
authors.lastname: Auwerx
authors.forename: Robert
authors.initials: R
authors.lastname: Esnouf
authors.forename: Erik
authors.initials: E
authors.lastname: De Clercq
authors.forename: Jan
authors.initials: J
authors.lastname: Balzarini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019380:Anti-HIV Agents / Q000494:pharmacology; D002384:Catalysis; D002415:Cats; D003848:Deoxyguanine Nucleotides / Q000494:pharmacology; D054306:Dideoxynucleotides; D017245:Foscarnet / Q000494:pharmacology; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors / Q000737:chemistry; D015497:HIV-1 / Q000201:enzymology*; D006801:Humans; D007093:Imidazoles; D016089:Immunodeficiency Virus, Feline / Q000201:enzymology*; D007700:Kinetics; D008969:Molecular Sequence Data; D019829:Nevirapine / Q000494:pharmacology; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013457:Sulfur Compounds
chemical_list: D019380:Anti-HIV Agents; D003848:Deoxyguanine Nucleotides; D054306:Dideoxynucleotides; D007093:Imidazoles; D011993:Recombinant Fusion Proteins; D018894:Reverse Transcriptase Inhibitors; D013457:Sulfur Compounds; D017245:Foscarnet; C031709:2',3'-dideoxyguanosine 5'-triphosphate; D019829:Nevirapine; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; C433874:capravirine