Computational Insights into Molecular Activation and Positive Cooperative Mechanisms of FFAR1 Modulators.

Free fatty acid receptor 1 (FFAR1), a member of class A in G-protein-coupled receptors (GPCRs), is a promising antidiabetic target. The crystal structure of FFAR1 revealed that one agonist (MK-8666) binds to the extracellular vestibule of this receptor, while another (AP8) occupies the surface pocket between transmembrane (TM) helices TM4 and TM5. In this study, we performed 1 μs unbiased molecular dynamics (MD) simulation on each of five systems, to uncover why two ligands in completely different sites both serve as agonists and how they exert a positive synergistic effect together. They are two agonist-bound systems (FFAR1_MK-8666 and FFAR1_AP8), a ternary complex system FFAR1_MK-8666_AP8, an antagonist-bound system (FFAR1_15i), and an unliganded (apo) system, among which the antagonist 15i-bound and apo systems were used as controls. The results showed that Y91