Molecular recognition in purinergic receptors. 1. A comprehensive computational study of the h-P2Y1-receptor.
P2Y receptors (P2Y-Rs) are attractive pharmaceutical targets due to their involvement in the modulation of many tissues and organs. The lack of experimental structural data on P2Y-Rs impedes structure-based drug design. The need to elucidate the receptor's molecular recognition, together with the limitations of previous receptor models, triggered the construction of a new molecular model for the h-P2Y1-R. Therefore, a h-P2Y1-R model was constructed by homology modeling using the 2.6 A crystal structure of bovine rhodopsin as a template and subsequently refined by constrained molecular dynamics (MD) simulations in a fully hydrated lipid bilayer environment. ATP was docked into the receptor binding site, followed by binding site refinement using Monte Carlo and MD simulations. Analysis of the h-P2Y1-R-ATP complex suggests that the triphosphate moiety is tightly bound by a multitude of interactions possibly including a Mg2+ ion, the ribose ring is not involved in specific interactions, and the adenine ring is bound via N1, N7, and N6. The molecular recognition of the h-P2Y1-R was further probed by ATP derivatives modified on the adenine ring, and correlated with EC50 values for these derivatives. Analysis of receptor:ligand complexes and quantum mechanical studies on model compounds support the role of both steric and electronic effects in improving H-bonding (via N1 and N6) and pi-stacking interactions. The computed h-P2Y1-R model was validated with respect to our previous biochemical results. We believe that this new model of the h-P2Y1-R provides the means for understanding phenomena such as the ligand's potency and receptor subtype selectivity.
Department of Chemistry, Gonda-Goldschmied Medical Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel.
Dan T
DT
Major
Bilha
B
Fischer
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry; D001665:Binding Sites; D003198:Computer Simulation; D006801:Humans; D008051:Lipid Bilayers; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D018048:Receptors, Purinergic P2 / Q000737:chemistry*; D058472:Receptors, Purinergic P2Y1; D012243:Rhodopsin / Q000737:chemistry; D040681:Structural Homology, Protein
D008051:Lipid Bilayers; C546382:P2RY1 protein, human; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D000255:Adenosine Triphosphate; D012243:Rhodopsin