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Revealing the Fluctuations of Flexible DNA in 3D
An international team of staff and users working at the Molecular Foundry has captured the first high-resolution 3D images from individual double-helix DNA segments attached at either end to gold nanoparticles
Significance and Impact
This unique imaging capability should lead to better understanding of disease-relevant proteins and the assembly process that forms DNA. It could also aid in the use of DNA segments as biomarkers, drug-delivery systems, computer memory and electronic devices.
- Developed at the Foundry, the imaging technique is called individual-particle electron tomography (IPET). IPET takes 2D images from different angles of the same object, which is flash-frozen to preserve the structure during cryo-EM imaging, to assemble a 3D image.
- The shapes of the coiled DNA strands, which were sandwiched between polygon-shaped gold nanoparticles, were imaged using IPET, with help from a protein-staining process and molecular simulation tools that provided structural details to the scale of about 2 nm.
- The molecular modeling simulated natural shape variations, called “conformations,” in the samples, and compared these shapes with observations.
L. Zhang, D. Lei, J. M. Smith, M. Zhang, H. Tong, X. Zhang, Z. Lu, J. Liu, A. P. Alivisatos & G. Ren. Nat Commun. 2016 7:11083.