Our research interests focus on membrane-confined processes such as fusion and fission, transport processes mediated by ion channels and protein pumps as well as protein-lipid and protein-protein interactions occurring at the membrane interface. To understand these processes on a molecular level, we pursue a bottom-up approach and develop and apply model membrane systems. Besides planar supported lipid bilayers and vesicles, such as giant unilamellar vesicles, that we use on a routine basis, we have established functional lipid bilayers on highly ordered pore arrays. These so-called pore-spanning membranes suspend nanometer- to micrometer-sized pores in an aluminum or silicon substrate. They separate two aqueous compartments and can hence be envisioned as an intermediate between supported and freestanding membranes. With these model systems in hand, we are able to mimic lipid domain formation, their dynamic behavior as well as their interaction with proteins demonstrated by the bacterial protein Shiga toxin. One focus of our research is on phosphoinositide-binding proteins such as the FERM domains of ezrin and focal adhesion kinase (FAK), as well as collybistin and their cytoskeletal organizing properties. Recently, we have been able to reconstitute part of the neuronal fusion machinery, allowing us to analyze the fusion between a planar pore-spanning membrane and a single vesicle at the molecular level. In addition, our goal is to further explore transport processes mediated by antimicrobial agents, ion channels such as connexons and bacterial porins, and protein pumps such as ATP synthases.
The topics include: