Molecular mechanism of action of monocyclam versus bicyclam non-peptide antagonists in the CXCR4 chemokine receptor.
AMD3465 is a novel, nonpeptide CXCR4 antagonist and a potent inhibitor of HIV cell entry in that one of the four-nitrogen cyclam rings of the symmetrical, prototype bicyclam antagonist AMD3100 has been replaced by a two-nitrogen N-pyridinylmethylene moiety. This substitution induced an 8-fold higher affinity as determined against (125)I-12G5 monoclonal CXCR4 antibody binding, and a 22-fold higher potency in inhibition of CXCL12-induced signaling through phosphatidylinositol accumulation. Mutational mapping of AMD3465 and a series of analogs of this in a library of 23 mutants covering the main ligand binding pocket of the CXCR4 receptor demonstrated that the single cyclam ring of AMD3465 binds in the pocket around AspIV:20 (Asp(171)), in analogy with AMD3100, whereas the N-pyridinylmethylene moiety mimics the other cyclam ring through interactions with the two acidic anchor-point residues in transmembrane (TM)-VI (AspVI:23/Asp(262)) and TM-VII (GluVII:06/Glu(288)). Importantly, AMD3465 has picked up novel interaction sites, for example, His(281) located at the interface of extracellular loop 3 and TM-VII and HisIII:05 (His(113)) in the middle of the binding pocket. It is concluded that the simple N-pyridinylmethylene moiety of AMD3465 substitutes for one of the complex cyclam moieties of AMD3100 through an improved and in fact expanded interaction pattern mainly with residues located in the extracellular segments of TM-VI and -VII of the CXCR4 receptor. It is suggested that the remaining cyclam ring of AMD3465, which ensures the efficacious blocking of the receptor, in a similar manner can be replaced by chemical moieties allowing for, for example, oral bioavailability.
Rosenkilde
Mette M
MM
Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, The Panum Institute, Copenhagen, DK-2200, Denmark, the. Electronic address: Rosenkilde@molpharm.dk.
Gerlach
Lars-Ole
LO
Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, The Panum Institute, Copenhagen, DK-2200, Denmark, the; 7TM Pharma A/S, Hørsholm, DK-2970, Denmark, and the.
Hatse
Sigrid
S
Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, 300, Belgium.
Skerlj
Renato T
RT
AnorMED, Langley, British Columbia V2Y 1N5, Canada.
Schols
Dominique
D
Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, 300, Belgium.
Bridger
Gary J
GJ
AnorMED, Langley, British Columbia V2Y 1N5, Canada.
Schwartz
Thue W
TW
Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, The Panum Institute, Copenhagen, DK-2200, Denmark, the; 7TM Pharma A/S, Hørsholm, DK-2970, Denmark, and the.
D000595:Amino Acid Sequence; D000818:Animals; D019380:Anti-HIV Agents / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001596:Benzylamines; D019556:COS Cells; D002522:Chlorocebus aethiops; D000080027:Cyclams; D006571:Heterocyclic Compounds / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011725:Pyridines / Q000378:metabolism / Q000494:pharmacology*; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors* / Q000737:chemistry
D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D001596:Benzylamines; D000080027:Cyclams; D006571:Heterocyclic Compounds; C503590:N-(1,4,8,11- tetraazacyclotetradecanyl-1,4-phenylenebis(methylene))-2-(aminomethyl)- pyridine; D011725:Pyridines; D019718:Receptors, CXCR4; C024560:cyclam; C088327:plerixafor