Time-resolved structures of β2-adrenergic receptor modulation by a photoswitchable beta-blocker

Stipp, R.; Bertrand, Q. C.; Trabuco, M.; Duran-Corbera, A.; Tindara Ignazzitto, M.; Glover, H.; Stierli, F.; Catena, J.; Carrillo, M.; Hartmann, S.; Seidel, H.-P.; Mulder, M.; Mason, T.; Kondo, Y.; Wranik, M.; Appleby, M.; Sager, C.; Sierra, R.; Gate, G.; Schleissner, P.; Cheng, X.; Weinert, T.; Cheng, R.; Mous, S.; Beale, J. H.; Kepa, M.; Llebaria, A.; Henning, M.; Rovira, X.; Standfuss, J.

doi:10.1101/2025.09.03.673938

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bioRxiv · 10.1101/2025.09.03.673938

Time-resolved structures of β2-adrenergic receptor modulation by a photoswitchable beta-blocker

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Abstract

G protein-coupled receptors (GPCRs) regulate essential physiological responses and are important drug targets, yet their ligand-induced conformational dynamics remain poorly understood. The {beta}2-adrenergic receptor ({beta}2AR) is a prominent member of the GPCR family. It regulates bronchial and vascular function and is a significant drug target, particularly in respiratory and smooth muscle-related disorders. We employed time-resolved crystallography at X-ray free-electron lasers (XFELs) to capture the conformational dynamics of {beta}2AR bound to photoazolol-1, a beta-blocker derivative developed for photopharmacological applications. Structural snapshots of the receptor bound to trans-photoazolol-1 (pre-photoconversion), a strained intermediate, and the fully photoisomerized cis-photoazolol-1 reveal an intricate interplay between ligand chemistry and receptor plasticity. Isomerization of the azobenzene moiety induces distinct conformational changes within the orthosteric pocket, altering interactions with the extracellular loop 2 and transmembrane helices 5 and 6. Supported by functional assays, these structural shifts suggest that photoazolol-1 transitions from an inverse agonist to a neutral antagonist upon photoactivation. Our findings uncover a mechanism of GPCR modulation reminiscent of rhodopsin activation and offer a framework for designing ligands that harness light-driven transitions to achieve spatiotemporal control of receptor function.

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Stipp, R., Bertrand, Q. C., Trabuco, M., Duran-Corbera, A., Tindara Ignazzitto, M., Glover, H., Stierli, F., Catena, J., Carrillo, M., Hartmann, S., Seidel, H.-P., Mulder, M., Mason, T., Kondo, Y., Wranik, M., Appleby, M., Sager, C., Sierra, R., Gate, G., Schleissner, P., Cheng, X., Weinert, T., Cheng, R., Mous, S., Beale, J. H., Kepa, M., Llebaria, A., Henning, M., Rovira, X., Standfuss, J.. 2025-09-06. Time-resolved structures of β2-adrenergic receptor modulation by a photoswitchable beta-blocker. https://doi.org/10.1101/2025.09.03.673938

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