BPS2026 – The energetics of slip and catch bonds in the actomyosin cytoskeleton

Actomyosin assemblies dissipate energy through ATP hydrolysis by myosin motors, with the network’s mechanical architecture shaping the dissipation pathways. We studied reconstituted actin networks crosslinked with either α-actinin (catch-bond-like) or fascin (slip-bond-like), combining microcalorimetry, ATPase assays, and rheology. We find that catch- and slip-bond crosslinkers differently regulate the balance between energy dissipation and mechanical load bearing—slip bonds facilitate stress relaxation under high motor activity, reducing stored elastic energy, while catch bonds maintain connectivity and sustain stress transmission. Our findings reveal how molecular bond kinetics modulate the energetic and mechanical response of active gels, suggesting a design principle for tuning active-matter dissipation by engineering crosslinker lifetimes.