Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 44: DNA/RNA and related enzymes
BP 44.5: Vortrag
Donnerstag, 19. März 2015, 16:15–16:30, H 1058
Random association of neighbouring replicons creates DNA replication factories. — •Jens Karschau1,2, Nazan Saner3, Toyaki Natsume3, Renata Retkute4, Conrad A. Nieduszynski5, J. Julian Blow3, Alessandro P.S. de Moura2, and Tomozuki U. Tanaka3 — 1MPI PKS, Dresden, Germany — 2University of Aberdeen, U.K. — 3University of Dundee, U.K. — 4University of Nottingham, U.K. — 5University of Oxford, U.K.
For simplicity, cartoons often depict DNA replication on a straight 1D line. In fact, we deal with a polymer that is packed and modified on different levels yielding higher order structures of organisation. Processing a DNA piece (as for example during DNA synthesis in clusters of replication factories) requires proper coordination amongst all individual machines (replicons) on it. However, it remains unknown how such replicons are organised at each replication factory.
We apply a 2 bead on a string model for two neighbouring replicons. We calculate analytically the probability for replicons to meet using Boltzmann statistics and then fit this with experimental data of replicon association in yeast to determine binding energies. This suffices to link our model to the dynamics of replicon activation and movement along DNA during the synthesis phase, to extrapolate from 2 neighbour interactions to the whole yeast-genome, and to describe properties of measured experimental distributions of fork numbers per cluster. Our model yields a near perfect match with the data suggesting that actively replicating units of DNA randomly associate with each other to form replication factories rather than being controlled by the cell.