Electrostatic interactions between DNA duplexes and nucleosome core particles
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
We will present some recent results of the theory of electrostatic interaction of parallel DNA duplexes in electrolyte solution 1-6. The DNA charge helicity, known to play an important role for many cellular processes involving DNA, is taken into account explicitly in this theory, on the level of the linearized Poisson-Boltzmann equation. Based on the results of the theory, we will a) describe the force-distance curves in dense DNA hexagonal assembly under the osmotic stress and implications of the observed DNA-DNA attraction to DNA condensation in the presence of multivalent counterions 2, b) introduce the electrostatic mechanism of sequence-specific recognition of torsionally flexible DNAs juxtaposed at close distances in solution 3,4, c) determine the degree of torsional deformations of DNA backbones induced by the mutual electrostatic interactions of DNA helices in dense assemblies/crystals 4, d) consider the pattern of DNA azimuthal frustrations on the hexagonal lattice as a consequence of the peculiar azimuthal DNA-DNA electrostatic pair interaction potential, e) discuss the effects of DNA helical non-ideality on DNA melting at elevated temperatures in dense DNA aggregates 5, f) analyze the formation and growth of DNA toroidal condensates in the presence of multivalent cations 6. DNA B-Z conformational transition at elevated salt concentrations will also be discussed 7. In the end, some new results on DNA-mediated electrostatic interactions of nucleosome core particles, which involve the effects of charge distribution on the nucleosome surface as well as the geometry of superhelical DNA wrapping around the histones, will be presented 8. Some outcomes of the model will be compared with statistical properties of azimuthal frustrations of the core particles observed in nucleosomal bilayers under the osmotic stress 9. Some implications of these results on structure of 30 nm chromatin fibers will also be addressed.\\
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