Effects of crowding and confinement on the transport and localization of DNA*

Two hallmarks of the intracellular environment are crowding and confinement. Macromolecular crowding within cells induces depletion interactions that can lead to anomalous transport, clustering, and sequestration of macromolecules such as DNA. Confinement by the lipid membrane of cells further dictates macromolecular dynamics and localization. Here, we investigate the transport of DNA molecules through crowded and confined environments, using dextran polymers as crowders and using lipids to encapsulate DNA and dextran in cell-sized droplets. By varying the dextran concentration and lipid composition we can control the degree of crowding and the properties of the confining boundary. We use differential dynamic microscopy (DDM) and spatial image autocorrelation analysis to quantify DNA diffusion rates and organization within the droplets, and the dependence of these properties on dextran concentration as well as droplet size and stiffness. Our results shed light on the effects on the coupled effects of crowding and confinement on biomacromolecular transport in cells.