DNA transport and conformational dynamics in active cytoskeleton composites*

The cytoskeleton plays a key role in governing the intracellular transport of macromolecules and, in turn, controlling biophysical phenomena such as drug delivery, protein function, and transfection. While the impact of crowding by cytoskeleton filaments, including actin and microtubules, has been widely studied, how the non-equilibrium dynamics of cytoskeletal networks driven by motor proteins impact intracellular transport is oft overlooked. Here, we couple single-molecule conformational tracking (SMCT) and differential dynamic microscopy (DDM) to elucidate the transport and conformational dynamics of ring and linear DNA molecules crowded by composite networks of actin and microtubules undergoing active myosin-driven rearrangement. Using DDM, we quantify the ensemble dynamics of the DNA, finding the transport properties (subdiffusive, ballistic, etc.) depend on both DNA size and topology. With SMCT, we measure dynamics that transition between subdiffusive and ballistic, and determine how ring and linear DNA molecules are conformationally affected by interactions with the active cytoskeleton networks.