Investigating the role of cross-linking in actin contractility

The actin cytoskeleton is a self-assembled material that acts as the mechanical scaffold of the cell and allows for processes like cell motility and division. Within the cell, protein cross-linkers are known to organize actin filaments into different assemblies. Physiological protein cross-linkers can differ in structural features like length and flexibility. Because of the limited variation of physiological cross-linkers, it is difficult to systematically study the role of cross-linker properties in actin assembly microstructure and mechanics. Here, we synthesize programmable crosslinkers with variable length and binding affinity. We find that myosin II motors induce contraction in the cross-linked actin networks, and we compare the contraction to physiologically cross-linked and entangled networks. We also use transmission electron microscopy to investigate the cross-linked actin assembly microstructures. This research will allow us to better understand how cells regulate their mechanics and microstructures, while also providing insight towards the structure-property relationship in complex soft materials.