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Br J Pharmacol. 2014 Jul;171(14):3364-75. doi: 10.1111/bph.12683.

A study of the molecular mechanism of binding kinetics and long residence times of human CCR5 receptor small molecule allosteric ligands.

Author information

1
Roche Palo Alto, Palo Alto, CA, USA; Institute for Rare and Neglected Diseases Drug Discovery, Mountain View, CA, USA.

Abstract

BACKGROUND AND PURPOSE:

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.

EXPERIMENTAL APPROACH:

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.

KEY 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 AND IMPLICATIONS:

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.

KEYWORDS:

CCR5; HIV-1 infection; allosteric; binding kinetics; maraviroc; molecular mechanism of action; pharmacology

PMID:
24628038
PMCID:
PMC4105926
DOI:
10.1111/bph.12683
[Indexed for MEDLINE]
Free PMC Article

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