A8: Impact of adhesion on the assembly and mechanics of a minimal actin cortex attached to the membrane via ezrin

Lead PI: Claudia Steinem

Collaborating PIs: Helmut Grubmüller, Andreas Janshoff, Stefan Klumpp, Sarah Köster, Tim Salditt

Overarching research question: How does adhesion modify the structure and mechanical properties of actomyosin networks attached at the inside of a GUV membrane and vice versa?

One of the hallmarks of the about 200-400 nm thick actomyosin network of eukaryotic cells is its attachment to the plasma membrane via e.g., ERM proteins (ezrin, radixin, moesin). This actomyosin cortex is constantly modified by adhesion to neighboring cells or to the extracellular matrix and the strength and the type of these adhesions are pivotal for regulating the assembly/disassembly of the cytoskeletal components. By a bottom-up approach, we generate giant unilamellar vesicles (GUVs) equipped with a membrane-attached actomyosin-cortex and the E. coli adaptor protein SspB to study how the network influences the surface adhesion of the GUV and how the adhesion influences the assembly and mechanics of the cortex. GUV surface adhesion is controlled by the light switchable iLID system, which can be switched by blue light to bind the membrane-anchored SspB.

Core field: experimental biophysics

PhD training objectives: data analysis (image analysis, microrheology); light-switchable proteins; membrane preparation; microfluidics; optical microscopy; protein biochemistry (expression, isolation and purification, labeling).