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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 39: Charged Soft Matter, Polyelectrolytes and Ionic Liquids
CPP 39.5: Vortrag
Dienstag, 17. März 2020, 10:30–10:45, ZEU 114
Helical twist of dsDNA depends on cation type and concentration — •Sergio Cruz-Leon1, Willem Vanderlinden2, Jan Lipfert2, and Nadine Schwierz1 — 1Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3 60438 Frankfurt am Main, Germany — 2Department of Physics, Nanosystem Initiative Munich and Center for Nanoscience, LMU Munich, Amalienstr. 54, 80799 Munich, Germany
The structural properties of double-stranded (ds)DNA determine many of its biological functions and are central for the development of precise artificial structures in nanotechnological applications. One of the most fundamental and iconic properties of DNA is its helicity, which depends on environmental factors such as temperature and salt concentration. While it has been known that DNA twist changes in a salt-dependent manner, the molecular origin of the effect remains unexplained. Here, we quantify the changes of dsDNA helical properties with ion type and concentration for a set of mono- and divalent cations. We combine single-molecule magnetic tweezers, molecular dynamics simulations, and theoretical modeling, and find that dsDNA changes its helical twist in a unique form depending on both ion type and concentration. Furthermore, we propose a mechanical model that captures the dependence on salt conditions for the changes in the dsDNA structure. Our structural insights and the mechanistic model facilitate the use of ion type and concentration as a tool to delicately manipulate DNA structures, for example, in the growing field of DNA origami technology.