Folding DNA into nucleosome and chromatin: dynamics

A theoretical framework for evaluating the approximate energy and dynamic properties associated with the folding of DNA into nucleosomes and chromatin is presented. For this purpose experimentally determined elastic constants of linear DNA and a simple fold geometry are assumed to derive constants for the higher order folding. The model predicts the correct order of magnitude for the experimentally determined Young’s and shear modulus of condensed chromatin. Thus we have demonstrated that the elastic properties of DNA are the primary determinant of the elastic properties of each folded state. The derived elastic constants are then used to predict the speed of propagation of small amplitude waves. It is shown that extension/compression, twist, bend or shear waves can be excite in each folded state. Introduction The folding of DNA into higher order structures is readily observed, but the path of DNA through these folded structures has not been determined Center for Bioenvironmental Research at Tulane and Xavier Universities 1430 Tulane Ave, SL-3 New Orleans, LA, 70112 * V: 504-988-6203/F: 504-585-6145 * [email protected] Center for Bioenvironmental Research at Tulane and Xavier Universities Phone: (504)-585-6145, E-mail: [email protected]