Local nucleosome dynamics facilitate chromatin accessibility in living mammalian cells

Genome information, which is three-dimensionally organized within cells as chromatin, is searched and read out by various proteins for diverse cell functions. Although how the protein factors find their targets remains unclear, the dynamic and flexible nature of chromatin is likely crucial. Using a combined approach of fluorescence correlation spectroscopy, single nucleosome imaging, and Monte Carlo computer simulations, researchers have demonstrated local chromatin dynamics in living mammalian cells.

Researchers at the National Institute of Genetics have shown that similar to interphase chromatin, dense mitotic chromosomes also have considerable chromatin accessibility. For both interphase and mitotic chromatin, they observed local fluctuation of individual nucleosomes (~50 nm movement/30 ms), which is caused by confined Brownian motion. Inhibition of these local dynamics by cross-linking impaired accessibility in the dense chromatin regions. Findings show that local nucleosome dynamics drive chromatin accessibility. It is proposed that this local nucleosome fluctuation is the basis for scanning genome information.

More information:
Hihara, S. et al., Local Nucleosome Dynamics Facilitate Chromatin Accessibility in Living Mammalian Cells. Cell Reports, Published online: December 2012
doi:10.1016/j.celrep.2012.11.008

Provided by National Institute of Genetics