DNA Weaved Into A Gridiron

Scientists have a new strategy for weaving DNA into complex nanostructures, which could find use as tools in crystallography, nanomedicine, and molecular electronics. Because DNA is robust and its bases pair up according to strict rules, nanotechnologists have used the nucleic acid as a building block for tiny structures. One such building technique, known as DNA origami, uses short single strands of DNA to hold a long single strand of the nucleic acid in a predetermined shape. A group led by Arizona State University’s Hao Yan, Yan Liu, and Dongran Han report a DNA origami method that uses short strands to fasten the long strand into structures that resemble a gridiron (Science, DOI: 10.1126/science.1232252). Such wire-frame structures allow the researchers to build complex three-dimensional structures that curve, such as spheres and screws. The basic unit of these nanostructures is a four-armed junction where two separate DNA helices meet, known as a Holliday junction. For the design to work, the Arizona State team had to deliberately distort classical Holliday junctions by flipping and rotating the DNA around the junction point. By varying the length of the DNA between each Holliday junction, they made the junctions flexible enough to build curved nanostructures.