title: Equation of state of looped DNA.
abstract: We derive the equation of state of DNA under tension that features a loop. Such loops occur transiently during DNA condensation in the presence of multivalent ions or permanently through sliding protein linkers such as condensin. The force-extension relation of such looped-DNA modeled as a wormlike chain is calculated via path integration in the semiclassical limit. This allows us to rigorously determine the high stretching asymptotics. Notably the functional form of the force-extension curve resembles that of straight DNA, yet with a strongly renormalized apparent persistence length. We also present analogous results for DNA under tension with several protein-induced kinks and/or loops. That means that the experimentally extracted single-molecule elasticity does not necessarily only reflect the bare DNA stiffness, but can also contain additional contributions that depend on the overall chain conformation and length.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Igor M
authors.initials: IM
authors.lastname: Kulić
authors.forename: Hervé
authors.initials: H
authors.lastname: Mohrbach
authors.forename: Rochish
authors.initials: R
authors.lastname: Thaokar
authors.forename: Helmut
authors.initials: H
authors.lastname: Schiessel
mesh_terms: D001703:Biophysics / Q000379:methods*; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004548:Elasticity; D004574:Electromagnetic Fields; D008956:Models, Chemical; D008958:Models, Molecular; D015233:Models, Statistical; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation
chemical_list: D004247:DNA