Quantification and visualization of protein-membrane and protein-protein interactions

Proteins use specific lipid receptors to attach to the plasma membrane. We are interested in the molecular interaction between membrane-confined receptors and proteins and how this interaction influences the overall membrane structure. In particular, we study the following systems:

Collybistin 2/Phosphoinositide/Gephyrin/Neuroligin 2
The organization of receptors into inhibitory GABAergic and glycinergic synapses is controlled by the scaffold protein gephyrin and the adaptor protein collybistin 2. Collybistin 2 is a guanine nucleotide exchange factor belonging to the Dbl family, which is composed of a Dbl homology (DH) and pleckstrin homology (PH) domains. In addition, a collybistin 2 isoform has an N-terminal src homology 3 (SH3) domain. We are interested in how the individual proteins of the GABAergic synapses interact with each other to generate the inhibitory postsynaptic domain. We use quantitative methods such as reflectometric interference spectroscopy to investigate this.


Ezrin/PIP₂/F-actin
One of the main players in linking the plasma membrane to the cytoskeleton is the protein ezrin, a member of the ezrin-radixin-moesin (ERM) family. Ezrin is found in a dormant conformation in the cytosol. Once activated, it is localized at the plasma membrane. We investigate, which factors lead to the activation of the protein, which results in the attachment of F-actin. To quantify and visualize ezrin and F-actin binding, we use reflectometric interference spectroscopy, fluorescence microscopy, and atomic force microscopy.


Shiga toxin/Gb₃
The bacterial Shiga toxin produced by Shigella dysenteriae and Shiga toxin producing E. coli strains (STECs) gets internalized into the cell after binding of the B-subunits to its natural receptor lipid Gb₃. We analyze, how the molecular structure of the lipid Gb₃ impacts the primary step of internalization of the toxin by a combination of fluorescence and atomic force microscopy.


In part funded by the Deutsche Forschungsgemeinschaft



and
the Max Planck School "Matter to Life"

s. SFB 1286 , RTG 2756 , and Matter to Life