Self-organization of curved living polymers: FtsZ protein filaments

Abstract

We present Monte Carlo simulations for a two-dimensional lattice model that mimics the interactions between filament forming proteins. The simulated structures are compared with filaments of the bacterial protein FtsZ observed with atomic force microscopy (AFM) on a mica surface immersed in solution. Protein filaments show curved living polymer structures with frequent monomer exchange, breaking and rearrangement, and condensing into aggregates through their lateral contacts. The polymorphic shape of the aggregates formed at low protein coverage and the textures observed at high coverage are analyzed and tuned with the monomer interaction parameters in the model. The comparison with the experimentally observed structures indicates that our model contains the essential aspects of the interactions between FtsZ monomers. A mutant variant of the protein may be described with modified values of the model interaction parameters.