title: Visualizing the Path of DNA through Proteins Using DREEM Imaging.
abstract: Many cellular functions require the assembly of multiprotein-DNA complexes. A growing area of structural biology aims to characterize these dynamic structures by combining atomic-resolution crystal structures with lower-resolution data from techniques that provide distributions of species, such as small-angle X-ray scattering, electron microscopy, and atomic force microscopy (AFM). A significant limitation in these combinatorial methods is localization of the DNA within the multiprotein complex. Here, we combine AFM with an electrostatic force microscopy (EFM) method to develop an exquisitely sensitive dual-resonance-frequency-enhanced EFM (DREEM) capable of resolving DNA within protein-DNA complexes. Imaging of nucleosomes and DNA mismatch repair complexes demonstrates that DREEM can reveal both the path of the DNA wrapping around histones and the path of DNA as it passes through both single proteins and multiprotein complexes. Finally, DREEM imaging requires only minor modifications of many existing commercial AFMs, making the technique readily available.
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Parminder
authors.initials: P
authors.lastname: Kaur
authors.affiliation: Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Zimeng M
authors.initials: ZM
authors.lastname: Li
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Kira C
authors.initials: KC
authors.lastname: Bradford
authors.affiliation: Department of Physics, North Carolina State University, Raleigh, NC 27695, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA. Electronic address: hong_wang@ncsu.edu.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599, USA. Electronic address: derie@unc.edu.
authors.forename: Dorothy A
authors.initials: DA
authors.lastname: Erie
mesh_terms: D004247:DNA / Q000737:chemistry*; D053843:DNA Mismatch Repair; D021621:Imaging, Three-Dimensional; D018625:Microscopy, Atomic Force; D009707:Nucleosomes / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D055672:Static Electricity
chemical_list: D009707:Nucleosomes; D011506:Proteins; D004247:DNA