Dresden 2020 – scientific programme
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BP: Fachverband Biologische Physik
BP 9: Poster II
BP 9.2: Poster
Monday, March 16, 2020, 17:30–19:30, P2/2OG
Influence of Ions on the Assembly of Vimentin Intermediate Filaments — •Manuela Denz1, Harald Herrmann2, and Sarah Köster1 — 1Institute of X-ray physics, University of Göttingen, Göttingen, Germany — 2Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany
The cytoskeleton is mainly composed of intermediate filaments (IFs), microfilaments and microtubules. In contrast to the conserved proteins actin and tubulin, IF proteins vary between different cell types. Despite the many different types, all IF proteins share the same secondary structure of a helical rod domain and intrinsically disordered head and tail domains. The assembly of IFs follows a hierarchical pathway. The assembly of the charged monomers into filaments can be triggered by ions. Here, we focus on the assembly of the IF protein vimentin using different ions. We test the influence of several ions with varying valencies, sizes and concentrations by small angle x-ray scattering (SAXS) and fluorescence microscopy (FM). SAXS probes primarily the lateral assembly of vimentin monomers into so-called unit-length filaments, while with FM the extended filaments are directly imaged. Vimentin assembled with monovalent ions forms single filaments. On the contrary, vimentin forms networks when assembled with multivalent ions. For those ions, vimentin filaments aggregate after exceeding a threshold concentration. With increasing valency of the ion, the threshold for aggregation of vimentin filaments is lowered. However, also differences between divalent ions can be observed, which can be explained by the Hofmeister effect.