Berlin 2015 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 22: Posters: Cytoskeletal filaments

BP 22.20: Poster

Dienstag, 17. März 2015, 14:00–16:00, Poster A

Mechanical properties of magnetosome filaments — •Bahareh Kiani, Damien Faivre, and Stefan Klumpp — Max Planck Institute of Colloids and Interfaces, Potsdam, Germany

Magnetotactic bacteria swim and orient in the direction of a magnetic field thanks to the magnetosome chain, a cellular "compass needle" that consists of a string of vesicle-enclosed magnetic nano-particles aligned on a cytoskeletal filament. Here we investigate the mechanical properties of such a chain, in particular the bending stiffness. We determine the contribution of magnetic interactions to the bending stiffness and the persistence length of the chain. This contribution is comparable to, but typically smaller than the contribution of the semi flexible filament. For a chain of magnetic nanoparticles without a semi flexible filament, the linear configuration is typically metastable and the lowest energy structures are closed chains (flux closure rings) without a net magnetic moment that are thus not functional as a cellular compass. Our calculations show that the presence of the cytoskeletal filament stabilizes the chain against ring closure, either thermodynamically or kinetically, depending on the stiffness of the filament, confirming that such stabilisation is one of the roles of this structure in these bacterial cells.