Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 27: Posters: Cytoskeletal Filaments

BP 27.3: Poster

Donnerstag, 29. März 2012, 17:30–19:30, Poster A

Length Regulation is an Intrinsic Property of Treadmilling Actin Filaments — •Christoph Erlenkämper and Karsten Kruse — Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken

Actin polymers constitute a major part of the cell cortex. The polymerisation of these filaments relies on the consumption of chemical energy through the hydrolysis of Adenosin-tri-phosphate (ATP). Together with the structural polarity of actin monomers, this can lead to treadmilling. In this state, the monomers are removed from one end of the filament at the same rate at which they are added at the other end. To investigate the conditions of treadmilling and the accompanying actin-length distribution, we formulate a three-state model of actin dynamics. It accounts for random dephosphorylation of actin-bound ATP along filaments and for the dependence of the various assembly rates on the nucleotide bound to actin monomers. For a range of experimentally accessible parameters, we find that treadmilling goes along with a stationary unimodal length distribution, which is due to a length-dependent monomer removal rate. In this case, the spontaneous disappearance of filaments is largely suppressed. We present analytical estimations of the typical filament length as well as for the variance of the ensuing length distributions and dicuss possible scenarios for in vivo length regulation.