Switchable domain partitioning and diffusion of DNA origami rods on membranes

Recently, DNA origami became a powerful tool for custom-shaped functional biomolecules. In this paper, we present the first approach towards assembling amphipathic three-dimensional DNA origami nanostructures and assessing their dynamics on the surface of freestanding phospholipid membranes. Our nanostructures were stiff DNA origami rods comprising six DNA helices. They were functionalized with hydrophobic cholesteryl-ethylene glycol anchors and fluorescently labeled at defined positions. Having these tools in hand, we could demonstrate not only the capability of the amphipathic nanorods to coat membranes of various phospholipid compositions, but also their switchable liquid-ordered/liquid-disordered partitioning on phase separated membranes. The observed translocation of our nanostructures between different domains was controlled by divalent ions. Moreover, selective fluorescent labeling enabled us to distinguish between the translational and rotational diffusion of our six helix bundles on the membranes by fluorescence correlation spectroscopy. The obtained data reveal how DNA origami can be employed as a valuable tool in membrane biophysics.