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BP: Fachverband Biologische Physik

BP 11: Posters: Cytoskeleton

BP 11.1: Poster

Tuesday, April 1, 2014, 09:30–12:30, P1

Time-resolved study of vimentin aggregation mediated by multivalent cations — •Christian Dammann and Sarah Köster — Institute for X-Ray Physics, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

Besides actin filaments and microtubules, intermediate filaments (IFs) are a major component of the cytoskeleton, forming networks and bundles in the cell. Attractive interactions between purified negatively charged IFs can be mediated by small cations and the understanding of these interactions increases the knowledge of the cytoskeleton on a fundamental level. Here, we directly image the attractive interaction of vimentin IFs in the presence of multivalent cations using time-lapse fluorescence imaging. The dynamics of this process are followed in a drop-based microfluidic device that allows for rapid imaging shortly after the first protein-cation contact. Given a necessary threshold cation concentration, we find that the aggregation process takes place on the order of a few minutes. During this process the initially freely fluctuating filaments form highly compacted networks. We interpret our findings with regard to competitive binding of mono- and multivalent cations onto the filaments and find an explanation for the observed attraction mechanism. Our result emphasizes the important role of electrostatics for cytoskeletal proteins. The findings are likely to be representative for the class of vimentin-like IFs.