Dresden 2014 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 2: DNA/RNA and related enzymes
BP 2.12: Vortrag
Montag, 31. März 2014, 12:45–13:00, ZEU 250
The car--parking model solves the random completion problem of DNA replication — •Jens Karschau1,2, Peter J. Gillespie3, J. Julian Blow3, and Alessandro P. S. de Moura1 — 1University of Aberdeen, Aberdeen, U.K. — 2MPI PKS, Dresden, Germany — 3University of Dundee, Dundee, U.K.
Eukaryotic cells have a large yet fixed amount of replication starting points --- origins of replication --- whose distance amongst them gives the time to synthesise a DNA segment, and the largest distance ultimately dictates when the last remaining segment is fully synthesised so that a cell is ready to divide.
A naive assumption would be to have origins equally separated from each other to partition the DNA into small segments, so to have minimal replication time. In a model for proteins finding origin positions randomly we show how these origin positions are taken as a result from the spatial requirement for proteins to bind stably at random positions. This explains experimental data of protein-DNA adsorption kinetics showing saturation over time. In a second step, this leads to a problem in statistical physics known as the car-parking problem. A model akin to this successfully explains the criteria to have small segments, because during protein adsorption it is more likely for origin-forming proteins to land in large empty regions on DNA. With our model we solve a long-standing conundrum: how to have optimal origin spacing when adsorption occurs at random sites, i.e. the random completion problem. Its solution directly emerges from physical principles of our adsorption model.