title: Indolopyridones inhibit human immunodeficiency virus reverse transcriptase with a novel mechanism of action.
abstract: We have discovered a novel class of human immunodeficiency virus (HIV) reverse transcriptase (RT) inhibitors that block the polymerization reaction in a mode distinct from those of the nucleoside or nucleotide RT inhibitors (NRTIs) and nonnucleoside RT inhibitors (NNRTIs). For this class of indolopyridone compounds, steady-state kinetics revealed competitive inhibition with respect to the nucleotide substrate. Despite substantial structural differences with classical chain terminators or natural nucleotides, these data suggest that the nucleotide binding site of HIV RT may accommodate this novel class of RT inhibitors. To test this hypothesis, we have studied the mechanism of action of the prototype compound indolopyridone-1 (INDOPY-1) using a variety of complementary biochemical tools. Time course experiments with heteropolymeric templates showed "hot spots" for inhibition following the incorporation of pyrimidines (T>C). Moreover, binding studies and site-specific footprinting experiments revealed that INDOPY-1 traps the complex in the posttranslocational state, preventing binding and incorporation of the next complementary nucleotide. The novel mode of action translates into a unique resistance profile. While INDOPY-1 susceptibility is unaffected by mutations associated with NNRTI or multidrug NRTI resistance, mutations M184V and Y115F are associated with decreased susceptibility, and mutation K65R confers hypersusceptibility to INDOPY-1. This resistance profile provides additional evidence for active site binding. In conclusion, this class of indolopyridones can occupy the nucleotide binding site of HIV RT by forming a stable ternary complex whose stability is mainly dependent on the nature of the primer 3' end.
authors.affiliation: Tibotec BVBA, Generaal De Wittelaan L 11B 3, 2800 Mechelen, Belgium. djochman@tibbe.jnj.com
authors.forename: Dirk
authors.initials: D
authors.lastname: Jochmans
authors.forename: Jérôme
authors.initials: J
authors.lastname: Deval
authors.forename: Bart
authors.initials: B
authors.lastname: Kesteleyn
authors.forename: Herwig
authors.initials: H
authors.lastname: Van Marck
authors.forename: Eva
authors.initials: E
authors.lastname: Bettens
authors.forename: Inky
authors.initials: I
authors.lastname: De Baere
authors.forename: Pascale
authors.initials: P
authors.lastname: Dehertogh
authors.forename: Tania
authors.initials: T
authors.lastname: Ivens
authors.forename: Marcia
authors.initials: M
authors.lastname: Van Ginderen
authors.forename: Bertrand
authors.initials: B
authors.lastname: Van Schoubroeck
authors.forename: Maryam
authors.initials: M
authors.lastname: Ehteshami
authors.forename: Piet
authors.initials: P
authors.lastname: Wigerinck
authors.forename: Matthias
authors.initials: M
authors.lastname: Götte
authors.forename: Kurt
authors.initials: K
authors.lastname: Hertogs
mesh_terms: D017931:DNA Primers; D004261:DNA Replication / Q000187:drug effects*; D024202:Electrophoretic Mobility Shift Assay; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors* / Q000235:genetics; D015497:HIV-1 / Q000201:enzymology*; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011728:Pyridones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D017422:Sequence Analysis, DNA
chemical_list: C517167:5-methyl-1-(4-nitrophenyl)-2-oxo-2,5-dihydro-1H-pyrido(3,2-b)indole-3-carbonitrile; D017931:DNA Primers; D007211:Indoles; D009570:Nitriles; D011728:Pyridones; D018894:Reverse Transcriptase Inhibitors; D054303:HIV Reverse Transcriptase