TY - JOUR
TI - Structural Characterization of Agonist Binding to an A3 Adenosine Receptor through Biomolecular Simulations and Mutagenesis Experiments
AU - Stamatis, D.
AU - Lagarias, P.
AU - Barkan, K.
AU - Vrontaki, E.
AU - Ladds, G.
AU - Kolocouris, A.
JO - Journal of Medicinal Chemistry
PY - 2019
VL - 62
TODO - 19
SP - 8831-8846
PB - American Chemical Society
SN - 0022-2623, 1520-4804
TODO - 10.1021/acs.jmedchem.9b01164
TODO - adenosine 5' (n ethylcarboxamide);  alanine;  glutamic acid;  piclidenoson;  adenosine;  adenosine A3 receptor;  adenosine A3 receptor agonist;  N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine, agonist potency;  animal cell;  Article;  carboxy terminal sequence;  comparative study;  drug binding site;  drug receptor binding;  drug selectivity;  drug structure;  female;  human;  hydrogen bond;  molecular docking;  molecular dynamics;  molecular mechanics;  molecular model;  nonhuman;  signal transduction;  site directed mutagenesis;  surface area;  animal;  binding site;  chemistry;  CHO cell line;  Cricetulus;  drug effect;  genetics;  hamster;  metabolism;  site directed mutagenesis;  thermodynamics, Adenosine;  Adenosine A3 Receptor Agonists;  Animals;  Binding Sites;  CHO Cells;  Cricetinae;  Cricetulus;  Humans;  Hydrogen Bonding;  Molecular Dynamics Simulation;  Mutagenesis, Site-Directed;  Receptor, Adenosine A3;  Signal Transduction;  Thermodynamics
TODO - The adenosine A3 receptor (A3R) binds adenosine and is a drug target against cancer cell proliferation. Currently, there is no experimental structure of A3R. Here, we have generated a molecular model of A3R in complex with two agonists, the nonselective 1-(6-amino-9H-purin-9-yl)-1-deoxy-N-ethyl-β-d-ribofuranuronamide (NECA) and the selective 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA). Molecular dynamics simulations of the wild-type A3R in complex with both agonists, combined with in vitro mutagenic studies revealed important residues for binding. Further, molecular mechanics-generalized Born surface area calculations were able to distinguish mutations that reduce or negate agonistic activity from those that maintained or increased the activity. Our studies reveal that selectivity of IB-MECA toward A3R requires not only direct interactions with residues within the orthosteric binding area but also with remote residues. Although V1695.30 is considered to be a selectivity filter for A3R binders, when it was mutated to glutamic acid or alanine, the activity of IB-MECA increased by making new van der Waals contacts with TM5. This result may have implications in the design of new A3R agonists. Copyright © 2019 American Chemical Society.
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