Dec 14, 2011
DNA nanoswitch flips open with force
Researchers at Harvard have nanoengineered a new tool for accurately measuring interactions between biological molecules in exquisite detail. A nanoscale mechanical switch made out of DNA is able to switch states under force to report the interactions between molecules of interest. When combined with modern single-molecule manipulation methods, this becomes a powerful, accessible and reliable system for measuring molecular kinetics and conformations at the single-molecule level.
The switch is fabricated using the method of DNA self-assembly, which is sometimes referred to as DNA origami. This takes advantage of the specific and reliable pairing between complementary bases to localize structures with sub-nanometer accuracy using standard test tube chemistry.
Easy and accessible approach
By mixing a long piece of single-stranded DNA with a carefully designed soup of short DNA oligomers, a looped single-molecule linker with an integrated receptor–ligand pair is self-assembled. Significantly, this approach is easy and accessible, requiring minimal time and equipment.
This breakthrough enables new and more reliable studies of biomolecular structure and function at the single-molecule level. Experiments show that this force-switchable molecule improves single molecule experiments by providing a tunable molecular "signature" to filter out spurious data. Furthermore, the force-switching behaviour of the linker is reversible, enabling repeated measurement of binding and unbinding of a single pair of molecules, paving the way for measurements of on-rates and population heterogeneity.
Next, the team plans to use these molecular constructs with its recently developed centrifuge force microscope (CFM) to perform high-throughput studies of antibody interactions.
This new approach will enable insights into how force affects single-molecule mechanics and dynamics, including enzymatic activity, binding of receptor-ligand pairs and drug interactions.
Further information can be found in the journal Nanotechnology.
About the author
Ken Halvorsen, PhD, is a research associate in Wesley Wong's lab at Harvard's Immune Disease Institute in Boston, US. His research is focused on molecular biophysics, with a strong interest in technology development, including the recently developed centrifuge force microscope. Wesley P Wong, PhD, is an assistant professor at Harvard University in the Departments of Biological Chemistry & Molecular Pharmacology and Pediatrics at Harvard Medical School, an investigator at the Immune Disease Institute and an associate faculty member at the Wyss Institute for Biologically Inspired Engineering at Harvard.