title: Competitive interaction of monovalent cations with DNA from 3D-RISM.
abstract: The composition of the ion atmosphere surrounding nucleic acids affects their folding, condensation and binding to other molecules. It is thus of fundamental importance to gain predictive insight into the formation of the ion atmosphere and thermodynamic consequences when varying ionic conditions. An early step toward this goal is to benchmark computational models against quantitative experimental measurements. Herein, we test the ability of the three dimensional reference interaction site model (3D-RISM) to reproduce preferential interaction parameters determined from ion counting (IC) experiments for mixed alkali chlorides and dsDNA. Calculations agree well with experiment with slight deviations for salt concentrations >200 mM and capture the observed trend where the extent of cation accumulation around the DNA varies inversely with its ionic size. Ion distributions indicate that the smaller, more competitive cations accumulate to a greater extent near the phosphoryl groups, penetrating deeper into the grooves. In accord with experiment, calculated IC profiles do not vary with sequence, although the predicted ion distributions in the grooves are sequence and ion size dependent. Calculations on other nucleic acid conformations predict that the variation in linear charge density has a minor effect on the extent of cation competition.
authors: BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers University 174 Frelinghuysen Road, Piscataway, NJ 08854, USA.
authors: George M
authors: GM
authors: Giambaşu
authors: Department of Biochemistry, Stanford University, Stanford, CA 94305, USA.
authors: Magdalena K
authors: MK
authors: Gebala
authors: BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers University 174 Frelinghuysen Road, Piscataway, NJ 08854, USA.
authors: Maria T
authors: MT
authors: Panteva
authors: Department of Physics & Astronomy, California State University, Northridge, CA 91330, USA.
authors: Tyler
authors: T
authors: Luchko
authors: BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers University 174 Frelinghuysen Road, Piscataway, NJ 08854, USA.
authors: David A
authors: DA
authors: Case
authors: BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers University 174 Frelinghuysen Road, Piscataway, NJ 08854, USA york@rutgers.edu.
authors: Darrin M
authors: DM
authors: York
mesh_terms: D002414:Cations, Monovalent / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D002414:Cations, Monovalent; C051802:triplex DNA; D012313:RNA; D004247:DNA