Self-Assembly of Magnetically-Functionalized Molecular Motors and Microtubules into Active Gels
The diversity of functions achieved by living cells result from the collective behavior of biological components that interact through multiple scales in time and space. The cytoskeleton constitutes one canonical system forming dynamic organizations when interacting with molecular motors. These materials constitute a state of active matter that exhibit out-of-equilibrium behavior with oriented order in the presence of energy. However, such active materials are highly dependent on the intrinsic properties of their constituents (fibers, molecular motors, energy), which render difficult to control their behavior. Being able to manipulate directly the constitutive elements of the active gel could provide additional control parameters. Here, we report a strategy to functionalize and manipulate active microtubule-based structures upon magnetic actuation. We engineered the protein nanocage ferritins as magnetic labels targeting molecular motors (Eg5 kinesin motors). We first mixed theses magnetic motors with individual microtubules, allowing their manipulation. In order to generate a magnetic-responsive gel, we then mix the magnetic motors with active microtubule-based structures and characterize their dynamic behavior. We found that the magnetic forces applied on magnetic motors slowdown the dynamic of microtubule structures as well as constrain their rotation. Our result highlights how genetically encoded magnetic elements, behaving as magnetic actuators, could perturb active gels.