Time-varying diffusion and conformations of topologically-active DNA in composites

The dynamics and conformations of DNA and other polymers are highly dependent on their topology, especially when the molecules are highly overlapping. DNA exploits the topological conversion from supercoiled to ring to linear forms to allow for processes ranging from replication to repair. Yet, how the dynamics and conformations of DNA molecules evolve during these enzymatically-driven topological operations is largely unknown. Here we use flourescence microscopy and single-molecule conformational tracking to determine the time-evolving center-of-mass motion and conformational size and shape of the DNA undergoing topological conversion from supercoiled and ring architectures to linear chains and fragments. We further investigate the role of dextran crowding on these non-equilibrium properties to shed light on our previous macrorheology results that demonstrated sharp transitions between elastic-like and fluid-like states in DNA-dextran composites.