Regulation of 2D DNA Nanostructures by the Coupling of Tile Curvatures and Arm Twists
DNA overwinding and underwinding between adjacent Holliday junctions have been applied in DNA origami constructs to design both left-handed and right-handed nanostructures. For a variety of DNA tubes assembled from small tiles, only a theoretical approach of the intrinsic tile curvature was previously used to explain their formation. Details regarding the quantitative and structural descriptions of the intrinsic tile curvature and its evolution in DNA tubes by coupling with arm twists were missing. In this work, we designed three types of tile cores from a circular 128 nucleotide scaffold by longitudinal weaving (LW), bridging longitudinal weaving (bLW), and transverse weaving (TW) and assembled their 2D planar or tubular nanostructures via inter-tile arms with a distance of an odd or even number of DNA half-turns. The biotin/streptavidin (SA) labeling technique was applied to define the tube configuration with addressable inside and outside surfaces and thus their component tile conformation with addressable concave and convex curvatures. Both chiral tubes possessing left-handed and right-handed curvatures could be generated by finely tuning p and q in bLW-E<sub>p/q</sub> designs (bLW tile cores joined together by inter-tile arms of an even number of half-turns with the arm length of p base pairs (bp) and the sticky end length of q nucleotides (nt)). We were able to assign the chiral indices (n,m) to each specific tube from the high-resolution AFM images, and thus estimated the tile curvature angle with a regular polygon model that approximates each tube’s transverse section. We attribute the curvature evolution of bLW-E<sub>p/q</sub> tubes composed of the same tile core to the coupling of the intrinsic tile curvature and different arm twists. A better understanding of the integrated actions of different types of twisting forces on DNA tubes will be much more helpful in engineering DNA nanostructures in the future.
