A8.2025: Impact of adhesion on the assembly and mechanics of a minimal actin cortex attached to the membrane via ezrin
Collaborating PIs: Helmut Grubmüller, Andreas Janshoff, Stefan Klumpp, Sarah Köster
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 200-400 nm thick actomyosin network of eukaryotic cells is its attachment to the plasma membrane via, e.g., ERM proteins (ezrin, radixin, moesin). The strength and the type of these adhesions are pivotal for regulating the assembly/disassembly of the cytoskeletal components. We will focus on the coupling of the actin cortex to the membrane by the protein ezrin that binds specifically and dynamically to its natural receptor lipid PtdIns(4,5)P2. The challenge will be to simultaneously insert ezrin and F-actin (and later further cytoskeletal components) into the lumen of giant unilamellar vesicles (GUVs). Once the system is established, we will analyze the architecture and mechanics of the composite membrane/F-actin network. We plan to use ezrin mutants that have different binding properties to F-actin. We will compare the obtained results with those gathered using theoretical approaches.
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).