@article{discovery10122926, year = {2021}, month = {February}, volume = {12}, journal = {Nature Communications}, number = {1}, title = {Base-pair resolution analysis of the effect of supercoiling on DNA flexibility and major groove recognition by triplex-forming oligonucleotides}, note = {Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.}, keywords = {Base Pairing, DNA, Circular, DNA, Superhelical, Microscopy, Atomic Force, Molecular Dynamics Simulation, Nucleic Acid Conformation, Oligonucleotides}, abstract = {In the cell, DNA is arranged into highly-organised and topologically-constrained (supercoiled) structures. It remains unclear how this supercoiling affects the detailed double-helical structure of DNA, largely because of limitations in spatial resolution of the available biophysical tools. Here, we overcome these limitations, by a combination of atomic force microscopy (AFM) and atomistic molecular dynamics (MD) simulations, to resolve structures of negatively-supercoiled DNA minicircles at base-pair resolution. We observe that negative superhelical stress induces local variation in the canonical B-form DNA structure by introducing kinks and defects that affect global minicircle structure and flexibility. We probe how these local and global conformational changes affect DNA interactions through the binding of triplex-forming oligonucleotides to DNA minicircles. We show that the energetics of triplex formation is governed by a delicate balance between electrostatics and bonding interactions. Our results provide mechanistic insight into how DNA supercoiling can affect molecular recognition, that may have broader implications for DNA interactions with other molecular species.}, url = {http://dx.doi.org/10.1038/s41467-021-21243-y}, author = {Pyne, ALB and Noy, A and Main, KHS and Velasco-Berrelleza, V and Piperakis, MM and Mitchenall, LA and Cugliandolo, FM and Beton, JG and Stevenson, CEM and Hoogenboom, BW and Bates, AD and Maxwell, A and Harris, SA} }