Wed, 05/02/2020 - 10:15
Campus Saarbrücken, E2 6, E04

Dr. Hannes Witt
Host: Prof. Ralf Seemann
Max-Planck-Institut for Dynamics and Selforganization Institute for Organic and Biomolecular Chemistry, University of Göttingen

From single filaments to many vesicles – understanding collective behavior of biological model systems

Life depends on processes spanning multiple orders of magnitude in length and time scales. In this talk I will present three different experimental approaches to create and understand supermolecular model systems reaching from single intermediate filaments to cell-sized vesicles with the goal to breach the gap between molecular and cellular biophysics. Examining the collective behavior of these model systems isolated from their cellular surrounding will help us to understand their biological function and identify common evolutionary design principles.

First I will discuss our work on the mechanical properties of the intermediate filament vimentin. Individual vimentin intermediate filaments were stretched by optical traps and atomic force microscopy. We observed fascinating mechanical properties, including a non-linear, velocity-dependent force response, a pronounced hysteresis between extension and relaxation and adaption to repeated mechanical stress.

Then I will demonstrate how a similar experimental approach can be adopted to study the interactions between lipid bilayers: Attaching membrane coated colloidal particles to the cantilever of an atomic force microscope allowed us to bring two bilayers in close contact and monitor their interactions with subnanometer precision. The power of this approach is demonstrated by monitoring SNARE-mediated membrane fusion with millisecond temporal resolution allowing us to get a glimpse into the energy landscape of membrane fusion.

Despite the considerable progress in the field of membrane biophysics, there is still a demand for more complex and tailored cell-like model systems. Therefore, I will close by presenting a new method for the production of multifunctional giant unilamellar vesicles using droplet-based microfluidics to create templates for the production of cell-sized vesicles, that can be equipped with reconstituted proteins.













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