Nucleosome spacing controls chromatin spatial structure and accessibility

Abstract

The spatial structure of chromatin in the eukaryotic nucleus is important for the regulation of gene expression and other fundamental cellular processes. The factors that influence structure and their effects are still uncertain. We studied the behavior of chromatin of 1.1 Mbp in physiological density utilizing a computer model. Basic physical properties of DNA and nucleosomes were sufficient to generate structures that matches well with published electron microscopic data. Our simulations demonstrate that the regularity of the spacing of nucleosomes, the fundamental building blocks of chromatin, is a crucial factor in determining the accessibility of the chromatin network to diffusive processes. No breakup of fiber like structures were observed at high molar density