Regensburg 2004 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 20: Physics of DNA

AKB 20.1: Hauptvortrag

Dienstag, 9. März 2004, 09:30–10:00, H40

Physics of DNA Compaction into Chromatin — •Helmut Schiessel — Max-Planck-Institute for Polymer Research, Theory Group, D 55021 Mainz

Chromatin is the dense complex between DNA and histone proteins that occupies the nuclei of plant and animal cells. At the lowest level the DNA is wrapped around protein spools forming so-called nucleosomes. The resulting string of nucleosomes is folded into the chromatin fiber. I will present theoretical models that allow to interpret recent experiments on the stretching of single nucleosomes and of chromatin fibers.

Our findings on single nucleosomes suggest a mechanism by which the nucleosome combines two seemingly contradictory features: being very stable and having its wrapped DNA highly accessible at the same time. Our results on fiber stretching show the delicate interplay between soft elasticity due to the DNA linker backbone and stiffening due to internucleosomal contacts – directing the folding of fibers at the next level of DNA compaction.

cf. also the review: H. Schiessel, J. Phys.: Condens. Matter 15 (2003) R699-R774