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BP: Fachverband Biologische Physik

BP 1: Statistical Physics in Biological Systems I (joint DY, BP)

BP 1.4: Talk

Monday, March 14, 2011, 11:15–11:30, ZEU 250

Looped Star Polymers: Lessons for Bacterial Chromosome Packaging — •Dieter Heermann, Miriam Fritsche, and Pascal Reiß — Institute für Theoretische Physik, Universität Heidelberg

Inspired by the topological organization of the circular Escherichia coli chromosome, which is compacted by separate domains, we study a polymer architecture consisting of a central ring to which either looped or linear arms are attached. A transition from a spherical to a toroidal shape takes place as soon as the inner ring becomes large enough for the attached arms to fit within its circumference. Building up a torus, the system flattens depending on the effective bending stiffness of the chain induced by entropic repulsion of the attached loops and, to a lesser extend, linear arms. We propose that the natural formation of a toroidal structure induced by a specific chromosome topology could be one driving force, among others, that nature exploits to ensure proper packaging of the genetic material within a rod-shaped nucleoid.