Inducing Lipid Domains in Membranes by Self‐Assembly of DNA Origami

Abstract

Self‐assembly of biological molecules and structures is a fundamental property of life. Whereas most biological functions are based on self‐assembled proteins and protein complexes, the self‐assembly of lipids is important for the spatial organization of heterogeneous cellular reaction environments and to catalyze cooperative interactions on/with membranes. Lipid domains or “rafts”, which are known to selectively recruit proteins, play an important functional role in sorting and trafficking of membrane components between subcellular organelles. However, how the recruitment and interactions of proteins in turn contributes to the formation and turnover of these structures has not been systematically addressed, due to the large variety in membrane–protein features and their spatiotemporal dynamics. The small size and transient nature of lipid domains adds to the complexity in visualizing them in living cells. Here, DNA origami is presented as a programmable tool to mimic protein clustering and assembly on membranes and illustrate how nanometer sized lipid domains coalesce into visible domains upon origami self‐assembly in defined patterns. Hence, the local membrane composition can be efficiently regulated by the self‐assembly of peripheral membrane binders. This reinforces the hypothesis that lipid rafts in cells occur as a result of membrane–protein interactions and, in particular, protein self‐assembly.

DNA Origami – Lipid Membrane Interactions Defined at Single-Molecular Resolution

“…50 This contrasts with previous studies where membrane anchors have been attached via polymeric and DNA linkers of 20 up to 10 nanometers in length on flat 32,33,49,50,54 and curved 19,23,28 DNA nanostructures. While long linkers increase conformational flexibility and hence improve membrane interaction, they can blur the picture of how anchor position influences binding 19,20,23,33,49,50 even though molecular accessibility of lipid anchors controls vesicles binding 54 and the related phenomenon of DNA duplex aggregation. 44 However, 3D geometries of DNA nanostructure are relevant parameters for biological applications such as shown by in vivo uptake of DNA origami into human cells via the pathway of small endosome vesicles for drug delivery applications.…”

“…First, we elucidated how DNA nanostructure-membrane interactions are influenced by the number and the geometric position of the membrane anchors in 3D geometries as opposed to flat nanostructures. 32,33,49,50,54 To maximize insight, the membrane anchors were placed close to the DNA nanostructure surface to force tight interaction to lipid bilayer vesicles. 50 This contrasts with previous studies where membrane anchors have been attached via polymeric and DNA linkers of 20 up to 10 nanometers in length on flat 32,33,49,50,54 and curved 19,23,28 DNA nanostructures.…”

“…32,33,49,50,54 To maximize insight, the membrane anchors were placed close to the DNA nanostructure surface to force tight interaction to lipid bilayer vesicles. 50 This contrasts with previous studies where membrane anchors have been attached via polymeric and DNA linkers of 20 up to 10 nanometers in length on flat 32,33,49,50,54 and curved 19,23,28 DNA nanostructures. While long linkers increase conformational flexibility and hence improve membrane interaction, they can blur the picture of how anchor position influences binding 19,20,23,33,49,50 even though molecular accessibility of lipid anchors controls vesicles binding 54 and the related phenomenon of DNA duplex aggregation.…”

“…While DNA nanotechnology excels at precisely tuning the shape and dimensions of 2D and 3D nanostructures spanning from the nanoscale 1-13 to the macroscale, 13-15 semifluid lipid bilayers stand out by compartmentalizing hydrophobic environments, 16 setting up concentration gradients for energy conversion, 17 and providing lateral diffusive platforms for enhanced molecular assembly. 18 Combining DNA nanotechnology with lipid membranes can unlock considerable synergy as illustrated by a range of DNA nanostructures that can mimic cellular cytoskeletons and shape membranes into biologically unprecedented forms, 19-23 define lipid domains, 24 selectively label leaflets, 25,26 measure membrane curvature, 27 fuse membrane bilayers, 28 spatially activate membrane proteins, 29,30 tune endosomal uptake, 31 facilitate macrostructure assembly, 32,33 and even help produce synthetic protocells. [34][35][36][37] In complementary approaches, DNA nanostructures can insert into lipid membranes to emulate the function of membrane proteins, including receptors, 38 nanopores, 39,40 gated channels, 41 membrane force sensors, 42 and lipid flippases.…”