Dresden 2014 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 13: Posters: DNA/RNA and related enzymes

BP 13.3: Poster

Dienstag, 1. April 2014, 09:30–12:30, P1

Nucleosome Breathing Facilitates Rapid DNA Packaging Into Chromatin — •Brendan Osberg, Johannes Nuebler, and Ulrich Gerland — Arnold-Sommerfeld Center for Theoretical Physics and Center for NanoScience, Theresienstraße 37, 80333 München

In eukaryotic cells DNA is packaged into chromatin: Nucleosomes, each consisting of 147 base pairs of DNA wrapped around a histone protein octamer, cover approximately 90% of the DNA. However, the mechanisms whereby cells achieve such a high coverage within a short time, e.g. after DNA replication, remain poorly understood.

It is well known that random sequential absorption processes of hard particles on a line lead to extremely slow filling kinetics beyond about 75% coverage, due to a "jamming" behavior. Of course, ATP consuming "remodeler" enzymes can speed up the filling of the DNA with nucleosomes.

However, we show that the breathing property of nucleosomes, where DNA transiently partially unwraps from the histones due to thermal fluctuations, can already eliminate the jamming behavior and alleviate the kinetic problem. We also consider effects whereby the steady progression of the replication fork could enable fast filling in its wake.