A Designed 3D Self-Assembled Crystalline DNA Array

Abstract

The precise control of the structure of matter is a central concern of the natural sciences. To this end, numerous investigators have developed self-assembling systems to produce targets of interest. Taking its cue from biological systems, structural DNA nanotechnology has used branched DNA motifs combined with cohesive ends to produce objects, nanomechanical devices and designed two-dimensional lattices. The details of these 2D lattices have been studied primarily by atomic force microscopy, whose resolution is 3-10 nm in typical analyses. The criteria for three dimensional self-assemblies are more strict, because the primary technique for their analysis is x-ray crystallography, whose resolution is limited only by the wavelength of the source (about 1 A). Previous efforts to produce self-assembled three-dimensional lattices have produced lattices that conformed to the design, but whose resolution was no better than 10 A, not really capable of revealing molecular structure. Here, we report the crystal structure at 5 A resolution of a self-assembled designed three-dimensional lattice based on the tensegrity triangle. Each edge of the tensegrity triangle contains two turns of DNA. The structure and sticky ends have been designed to be 3-fold symmetric, and at this resolution it appears to be so. The data are of sufficient quality to demonstrate clearly that it is possible to design a 3D lattice using the techniques of self-assembly based on molecular recognition. This research supported by NIGMS, NSF, ARO and the W.M. Keck Foundation.