Revealing Water-Mediated Activation Mechanisms in the Beta 1-Adrenergic Receptor via OneOPES-Enhanced Free Energy Landscapes

The beta-1 adrenergic receptor (ADRB1) is a prominent pharmacological target due to its critical role in regulating cardiovascular function and is therefore at the forefront of therapeutic interventions in heart diseases. Here we explore the activation mechanism of ADRB1 in both apo (unbound) and holo (adrenaline-bound) forms with OneOPES, a novel multi-replica enhanced sampling simulation algorithm. Our approach leads to converged and reproducible free energy landscapes as shown by independent simulations and identifies key water-mediated interactions that ease structural rearrangements crucial for the activation of ADRB1. The detailed computational analysis provides a comprehensive understanding of the effects of adrenaline on ADRB1’s activation mechanism as well as the role of sodium ions, protonation states and microswitches. Our methodology can be adapted to other ligands and receptors and serves as a blueprint for computational exploration of agonist-induced activation of ADRB1 and other class A GPCRs, paving the way for the development of drugs with fine-tuned modulatory effects.