Microswitch-Guided Sampling for the Detection of Ligand Signaling Bias in GPCR Systems
Biased signaling occurs when a ligand preferentially activates a specific signaling pathway at a certain receptor within a particular cellular environment. As pharmaceuticals, functionally selective (biased) compounds can engage beneficial signaling pathways while avoiding those linked to adverse effects, resulting in safer and targeted therapeutics. However, existing experimental methods for…
Microswitch-Guided Sampling (MGS) is a computational technique that leverages conformational alterations in molecular switches to evaluate ligand bias in G protein-coupled receptor (GPCR) systems. Utilizing short all-atom molecular dynamics simulations of the beta1-adrenergic receptor, chemokine receptor CXCR3, and the -opioid receptor in the presence of G protein or beta-arrestin and known biased ligands, researchers pinpointed microswitches whose changes correlate with the activation of a specific signaling pathway.
These microswitch change time points were then used to sample simulation trajectories, which served as initiators for 500 nanosecond ligand-swapped simulations. This process involved exchanging biased ligands between complexes, allowing for the observation of distinct conformational changes in complexes interacting with pathway-activating and non-activating ligands.
The study reveals that MGS effectively distinguishes G protein-biased from beta-arrestin-biased ligands across at least two of the three examined systems. This novel methodology offers a rapid, nanosecond-scale computational approach to identify functional selectivity in GPCR systems, potentially enabling the accelerated development of targeted therapeutics with enhanced safety profiles.
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