Regensburg 2007 – scientific programme
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BP: Fachverband Biologische Physik
BP 7: Fibers and Bundles
BP 7.6: Talk
Monday, March 26, 2007, 17:30–17:45, H44
The Influence of internucleosomal interaction and local structure on the geometry of large chromatin fibers — •René Stehr1, Nick Kepper2, Karsten Rippe2, and Gero Wedemann1 — 1Fachhochschule Stralsund, System Engineering and Information Management, Zur Schwedenschanze 15, D-18435 Stralsund, Germany — 2Kirchhoff-Institut für Physik, Molecular Biophysics Group, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 227, D-69120 Heidelberg, Germany
The structure of the genetic material plays a major role in the regulation of gene expression. In eukaryotic cells the DNA is folded with histone proteins into chromatin. The internal structure of chromatin at physiological ionic strength is unknown.
We utilize computer simulations to study both the effect of different interaction potentials betweeen nucleosomes as well as changes to the nucleosome geometry. Our analysis revealed that the previously used potentials (e.g. Gay-Berne potential) are not compatible with the formation of stable chromatin fibers under physiological potential strengths while other geometries do. Furthermore, we extended the "two angle" model for the description of the DNA-nucleosoe geometry.
The results of our analysis identify the internucleosomal interaction and the local geometry at the nucleosomes as key determinants for the organization of the chromatin fiber. Modifications of these parameters by biological factors could be used to control the accessibility of DNA in the fiber in vivo.