Abstract
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-Ep/q 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-Ep/q 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.
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