Photoresponsive molecular tweezers modulate Taspase 1 activity.

Light serves as an exceptional stimulus for the precise spatiotemporal regulation of protein activity and protein-protein interactions. Here, we introduce a light-responsive supramolecular ligand system designed to modulate Taspase 1, a protease critical for embryogenesis and implicated in tumor progression. Our approach utilizes photoswitchable divalent molecular tweezers engineered to target lysine-rich regions within the Taspase 1 loop. By incorporating arylazopyrazole (AAP) photoswitches, we achieve dynamic and reversible control of ligand binding. These photoswitches exhibit high photostationary states, excellent reversibility, and prolonged thermal stability of the isomer, ensuring reliable switching without photodegradation. The tweezer distance varies between and isomers, enabling tunable binding interactions. Through a combination of surface plasmon resonance, enzymatic cleavage assays, and molecular dynamics simulations, we demonstrate that these ligands bind Taspase 1 with low micromolar affinity and effectively inhibit its proteolytic activity. While isomerization did not significantly affect the inhibition of protein-protein interaction, the -isomers of larger tweezers exhibited powerful enzyme inhibition, likely due to their ability to bridge lysines flanking the active site. This photoswitchable tweezer system provides a versatile tool for light-controlled modulation of protein function, offering new opportunities for selectively targeting lysine-rich proteins in dynamic biological environments.