Dimerization and ligand binding affect the structure network of A2A adenosine receptor

Francesca Fanelli, Angelo Felline

Abstract

G protein Coupled Receptors (GPCRs) are allosteric proteins whose functioning fundamentals are the communication between the two poles of the helix bundle. The representation of GPCR structures as networks of interacting amino acids can be a meaningful way to decipher the impact of ligand and of dimerization/ oligomerization on the molecular communication intrinsic to the protein fold. In this study, we predicted likely homodimer architectures of the A2AR and investigated the effects of dimerization on the structure network and the communication paths of the monomeric form. The results of this study emphasize the roles of helix 1 in A2AR dimerization and of highly conserved amino acids in helices 1, 2, 6 and 7 in maintaining the structure network of the A2AR through a persistent hub behavior as well as in the information flow between the extracellular and intracellular poles of the helix bundle. The arginine of the conserved E/DRY motif, R3.50, is not involved in the communication paths but participates in the structure network as a stable hub, being linked to both D3.49 and E6.30 like in the inactive states of rhodopsin. A2AR dimerization affects the communication networks intrinsic to the receptor fold in a way dependent on the dimer architecture. Certain architectures retain the most recurrent communication paths with respect to the monomeric antagonist-bound form but enhancing path numbers and frequencies, whereas some others impair ligand-mediated communication networks. Ligand binding affects the network as well. Overall, the communication network that pertains to the functional dynamics of a GPCR is expected to be influenced by ligand functionality, oligomeric order and architecture of the supramolecular assembly. This article is part of a Special Issue entitled: “Adenosine Receptors”.

Biochimica et Biophysica Acta 1808 (2011) 1256-1266 PMID: 20713020