Coarse-Grained Simulations Reveal Mechanisms of Fission Yeast Cytokinesis

Abstract

Cytokinesis in fission yeast requires the presence of the actomyosin ring that constricts the membrane to divide the cell. Despite lots of effort, the molecular mechanism by which the ring tension is created remains poorly understood. This is largely due to the lack of structural details of of the ring, e.g., how actin filaments (F-actin) are arranged and what myosin conformations exist. As several models exist we decided to develop a computational approach to test whether these models are biophysically reasonable when simulated. Starting with a very simple model in which only actin filaments and bipolar myosin molecules are present we showed that myosin could slide F-actin but contraction did not occur. Addition of actin crosslinkers then helped contract the ring which in turn could pull down a coarse-grained membrane added to the system later. By tuning parameters and properties of the ring's components to match with data from electron cryotomography, we showed that coarse-grained simulations could help reveal the mechanism for the ring constriction.

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