title: A study of the molecular mechanism of binding kinetics and long residence times of human CCR5 receptor small molecule allosteric ligands.
abstract: OBJECTIVE
  The human CCR5 receptor is a co-receptor for HIV-1 infection and a target for anti-viral therapy. A greater understanding of the binding kinetics of small molecule allosteric ligand interactions with CCR5 will lead to a better understanding of the binding process and may help discover new molecules that avoid resistance.
  
  
  METHODS
  Using [(3) H] maraviroc as a radioligand, a number of different binding protocols were employed in conjunction with simulations to determine rate constants, kinetic mechanism and mutant kinetic fingerprints for wild-type and mutant human CCR5 with maraviroc, aplaviroc and vicriviroc.
  
  
  RESULTS
  Kinetic characterization of maraviroc binding to the wild-type CCR5 was consistent with a two-step kinetic mechanism that involved an initial receptor-ligand complex (RA), which transitioned to a more stable complex, R'A, with at least a 13-fold increase in affinity. The dissociation rate from R'A, k-2 , was 1.2 × 10(-3) min(-1) . The maraviroc time-dependent transition was influenced by F85L, W86A, Y108A, I198A and Y251A mutations of CCR5.
  
  
  CONCLUSIONS
  The interaction between maraviroc and CCR5 proceeded according to a multi-step kinetic mechanism, whereby initial mass action binding and later reorganizations of the initial maraviroc-receptor complex lead to a complex with longer residence time. Site-directed mutagenesis identified a kinetic fingerprint of residues that affected the binding kinetics, leading to the conclusion that allosteric ligand binding to CCR5 involved the rearrangement of the binding site in a manner specific to each allosteric ligand.
authors.affiliation: Roche Palo Alto, Palo Alto, CA, USA; Institute for Rare and Neglected Diseases Drug Discovery, Mountain View, CA, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Swinney
authors.forename: Paul
authors.initials: P
authors.lastname: Beavis
authors.forename: Kai-Ting
authors.initials: KT
authors.lastname: Chuang
authors.forename: Yue
authors.initials: Y
authors.lastname: Zheng
authors.forename: Ina
authors.initials: I
authors.lastname: Lee
authors.forename: Peter
authors.initials: P
authors.lastname: Gee
authors.forename: Jerome
authors.initials: J
authors.lastname: Deval
authors.forename: David M
authors.initials: DM
authors.lastname: Rotstein
authors.forename: Marianna
authors.initials: M
authors.lastname: Dioszegi
authors.forename: Palani
authors.initials: P
authors.lastname: Ravendran
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Surya
authors.initials: S
authors.lastname: Sankuratri
authors.forename: Rama
authors.initials: R
authors.lastname: Kondru
authors.forename: Georges
authors.initials: G
authors.lastname: Vauquelin
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects*; D001665:Binding Sites / Q000187:drug effects; D065100:CCR5 Receptor Antagonists / Q000737:chemistry / Q000494:pharmacology*; D003510:Cyclohexanes / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D008024:Ligands; D000077592:Maraviroc; D019713:Receptors, CCR5 / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013997:Time Factors; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D065100:CCR5 Receptor Antagonists; C584933:CCR5 protein, human; D003510:Cyclohexanes; D008024:Ligands; D019713:Receptors, CCR5; D014230:Triazoles; D000077592:Maraviroc
keywords: CCR5; HIV-1 infection; allosteric; binding kinetics; maraviroc; molecular mechanism of action; pharmacology