Cross-linker binding strength influences actin assembly microstructure and myosin II driven remodeling

The actin cytoskeleton is a self-assembled material that acts as the mechanical scaffold of the cell. Within the cell, protein cross-linkers organize actin filaments into assemblies with various microstructures that support distinct physiological functions. These protein cross-linkers differ in structural features. To decouple the role of individual cross-linker properties in actin assembly microstructure and mechanics, we synthesize programmable cross-linkers using a DNA linker coupled to binding domains. We find that high affinity cross-linkers induce actin bundling, while low affinity cross-linkers form actin networks. Myosin II motors remodel and contract all cross-linked networks tested in distinct ways from uncross-linked networks. We find that networks with high affinity cross-linkers have different myosin induced dynamics than networks with low affinity cross-linkers. This research expands our understanding of how cells regulate their mechanics and microstructures, while also providing insight towards the structure-property relationship in complex soft materials.