title: Direct measurement of the dielectric polarization properties of DNA.
abstract: The electric polarizability of DNA, represented by the dielectric constant, is a key intrinsic property that modulates DNA interaction with effector proteins. Surprisingly, it has so far remained unknown owing to the lack of experimental tools able to access it. Here, we experimentally resolved it by detecting the ultraweak polarization forces of DNA inside single T7 bacteriophages particles using electrostatic force microscopy. In contrast to the common assumption of low-polarizable behavior like proteins (εr ∼ 2-4), we found that the DNA dielectric constant is ∼ 8, considerably higher than the value of ∼ 3 found for capsid proteins. State-of-the-art molecular dynamic simulations confirm the experimental findings, which result in sensibly decreased DNA interaction free energy than normally predicted by Poisson-Boltzmann methods. Our findings reveal a property at the basis of DNA structure and functions that is needed for realistic theoretical descriptions, and illustrate the synergetic power of scanning probe microscopy and theoretical computation techniques.
authors.affiliation: Department of Structure of Macromolecules, Centro Nacional de Biotecnologia-Consejo Superior de Investigaciones Cientificas, Campus Cantoblanco, 28049 Madrid, Spain;
authors.forename: Ana
authors.initials: A
authors.lastname: Cuervo
authors.affiliation: Institute for Research in Biomedicine-Barcelona Supercomputing Center Joint Research Program in Computational Biology, Institute for Research in Biomedicine-Barcelona, 08028 Barcelona, Spain;
authors.forename: Pablo D
authors.initials: PD
authors.lastname: Dans
authors.affiliation: Department of Structure of Macromolecules, Centro Nacional de Biotecnologia-Consejo Superior de Investigaciones Cientificas, Campus Cantoblanco, 28049 Madrid, Spain; Instituto Madrileño de Estudios Avanzados en Nanociencia, Cantoblanco, 28049 Madrid, Spain;
authors.forename: José L
authors.initials: JL
authors.lastname: Carrascosa
authors.affiliation: Institute for Research in Biomedicine-Barcelona Supercomputing Center Joint Research Program in Computational Biology, Institute for Research in Biomedicine-Barcelona, 08028 Barcelona, Spain; Facultat de Biologia, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, 08028 Barcelona, Spain;
authors.forename: Modesto
authors.initials: M
authors.lastname: Orozco
authors.affiliation: Institut de Bioenginyeria de Catalunya, 08028 Barcelona, Spain; and Departament d'Electrònica, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Gomila
authors.affiliation: Institut de Bioenginyeria de Catalunya, 08028 Barcelona, Spain; and Departament d'Electrònica, Universitat de Barcelona, 08028 Barcelona, Spain laura.fumagalli28@gmail.com.
authors.forename: Laura
authors.initials: L
authors.lastname: Fumagalli
mesh_terms: D017123:Bacteriophage T7 / Q000737:chemistry / Q000235:genetics*; D002213:Capsid / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry; D058266:Dielectric Spectroscopy / Q000379:methods*; D055664:Electrochemical Techniques; D008024:Ligands; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D008024:Ligands; D009687:Nuclear Proteins; D004247:DNA
keywords: DNA packaging; DNA–ligand binding; Poisson–Boltzmann equation; atomic force microscopy; atomistic simulations