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BP: Fachverband Biologische Physik

BP 41: Biomaterials and Biopolymers II (joint CPP/BP)

BP 41.10: Vortrag

Donnerstag, 3. April 2014, 17:45–18:00, ZEU 222

Induction phase of entropic DNA segregation in bacteria — •Elena Minina and Axel Arnold — Institute for Computational Physics, University of Stuttgart, Allmandring 3, 70569, Stuttgart, Germany

Cell division is a complex mechanism which consists of two main processes -- DNA replication and segregation. In primitive bacteria such as Escherichia coli, which has a rod-like shape and a single chromosome, the dsDNA molecule of the mother cell is split into two daughter strands which are complemented again. During the replication these daughter strands segregate, i.e. move towards opposite sides of the cell to create two new cells. It was previously shown that the segregation of confined linear polymers (DNA) is entropically driven and does not need to involve any active mechanisms [A. Arnold and S. Jun, Phys. Rev. E 76 (2007)]. However, the initial configuration of fully overlapping polymers is perfectly symmetrical. Initiation of segregation requires to break this symmetry. This period of time is called induction and has a rather broad distribution, which significantly reduces the efficiency of entropic segregation. In the present study we investigate the induction more closely and determine the mechanism that breaks the symmetry of the system. Combination of MD simulations with theory based on free energy calculation shows that the induction is not diffusive as it was predicted, but is a process related to the ordering of the polymer ends during breaking the system symmetry, when the tail of one strand tries to pass the tail of the other strand. Our findings might explain the segregation delay observed in experiments on E.coli.