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Molecular mechanism of positive allosteric modulation of the metabotropic glutamate receptor 2 by JNJ‐46281222
Author(s) -
Doornbos Maarten L J,
PérezBenito Laura,
Tresadern Gary,
MulderKrieger Thea,
Biesmans Ilse,
Trabanco Andrés A,
Cid Jose María,
Lavreysen Hilde,
IJzerman Adriaan P,
Heitman Laura H
Publication year - 2016
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.13390
Subject(s) - allosteric regulation , allosteric modulator , metabotropic glutamate receptor , metabotropic glutamate receptor 2 , chemistry , binding site , radioligand , mutagenesis , allosteric enzyme , glutamate receptor , biophysics , receptor , biochemistry , biology , mutant , gene
Background and Purpose Allosteric modulation of the mGlu 2 receptor is a potential strategy for treatment of various neurological and psychiatric disorders. Here, we describe the in vitro characterization of the mGlu 2 positive allosteric modulator (PAM) JNJ‐46281222 and its radiolabelled counterpart [ 3 H]‐JNJ‐46281222. Using this novel tool, we also describe the allosteric effect of orthosteric glutamate binding and the presence of a bound G protein on PAM binding and use computational approaches to further investigate the binding mode. Experimental Approach We have used radioligand binding studies, functional assays, site‐directed mutagenesis, homology modelling and molecular dynamics to study the binding of JNJ‐46281222. Key Results JNJ‐46281222 is an mGlu 2 ‐selective, highly potent PAM with nanomolar affinity ( K D = 1.7 nM). Binding of [ 3 H]‐JNJ‐46281222 was increased by the presence of glutamate and greatly reduced by the presence of GTP, indicating the preference for a G protein bound state of the receptor for PAM binding. Its allosteric binding site was visualized and analysed by a computational docking and molecular dynamics study. The simulations revealed amino acid movements in regions expected to be important for activation. The binding mode was supported by [ 3 H]‐JNJ‐46281222 binding experiments on mutant receptors. Conclusion and Implications Our results obtained with JNJ‐46281222 in unlabelled and tritiated form further contribute to our understanding of mGlu 2 allosteric modulation. The computational simulations and mutagenesis provide a plausible binding mode with indications of how the ligand permits allosteric activation. This study is therefore of interest for mGlu 2 and class C receptor drug discovery.