Resolving the Spatiotemporal Power Demand to Sustain Ordered Motor-Microtubule Assemblies

Living matter produces a variety of spatiotemporal structures and patterns that are not present in their nonliving counterparts. Often, these ordered, non-equilibrium steady states are sustained through an influx of energy from the environment. Careful examination of when and where living systems direct energy helps us understand the principles dictating such ordering and can motivate development of non-equilibrium theories. Here, we investigate the energetic cost of assembling an ordered aster from a disordered, uniform mixture of microtubules and kinesin motors. Using a fluorescent ATP sensor, we perform the first careful measurement of ATP consumption through space and time on an in vitro cytoskeletal network. Our experiments reveal the emergence of radial ATP gradients. We successfully predict how a given motor profile generates these ATP distributions with reaction-diffusion modeling and finite element simulations. With our results, we compare the power per volume required by our cytoskeletal networks with the known power per volume expenditure in cells. Evoking the direct quantification of energetic fluxes, from our spatial measurements, unlocks future exploration of what steady states are accessible to cells and how the cytoskeleton drives spatial organization.