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BP: Fachverband Biologische Physik

BP 36: Cytoskeletal Filaments I

BP 36.4: Hauptvortrag

Donnerstag, 19. März 2020, 15:45–16:15, SCH A251

Mechanical properties of intermediate filaments at high strains — Johanna Forsting, Julia Kraxner, Charlotta Lorenz, Anna Schepers, and •Sarah Köster — Institute for X-Ray Physics, University of Göttingen

Mechanical properties of eukaryotic cells are to a great part determined by the cytoskeleton, a composite biopolymer network composed of three filament systems -- intermediate filaments, F-actin and microtubules -- along with cross-linkers and molecular motors. While actin and tubulin are conserved between cell types and organisms, intermediate filament proteins are expressed in a cell type dependent manner. It has been shown previously that the presence of filaments in a cell has an influence on cell mechanics. Here we unravel the role of the mechanical properties of the individual filaments, in particular at high strains. The molecular architecture of intermediate filaments displays several particularities, such as a strictly hierarchical build-up and multipe alpha-helical domains arranged in parallel. This architecture gives rise to intriguing mechanical properties, such as high flexibility and extreme extensibility. We employ optical traps to obtain precise force-strain data of vimentin and keratin intermediate filaments and model our data by Monte Carlo simulations. We are thus able to show differences between different types of intermediate filaments, as well as a dependence on the ionic anvironment and pH, thus revealing a strong influence of charge interactions.