How charge fluctuations modulate complexation of DNA around a histone cylinder
Department of Physics and PCTP, Pohang University of Science and Technology - Pohang, 790-784, South Korea
Received: 22 July 2013
Accepted: 30 September 2013
It is an enigma that in a nucleosome complex, a single DNA winds around a histone protein core about 1.6–1.8 times. We find that the optimal winding can be given by the charge density fluctuations on the DNA contour due to multivalent counterions binding and unbinding in a physiological ionic background. From a model free energy of the DNA wound on the histone cylinder, where the charge fluctuations induce the intra-DNA attraction, we establish the conditions and a phase diagram for stability of the complex as a function of the salt and divalent cations concentrations.
PACS: 82.35.Rs – Polyelectrolytes / 87.15.A- – Theory, modeling, and computer simulation
© EPLA, 2013