Membrane-based biomimetic nano- and micro-compartments (Prof. Dr. Claudia Steinem)
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. We are highly interested in phosphoinositide-binding proteins such as ezrin and collybistin and their cytoskeleton-organizing properties as well as epsin, which is involved in the early steps of endocytosis. Recently, we managed to reconstitute parts of the neuronal fusion machinery into pore-spanning membranes to study the exocytotic process of membrane fusion on a single vesicle level. We aim to investigate transport processes mediated by ion channels such as artificial helix bundles, connexons, and bacterial porins as well as protein pumps such as bacteriorhodopsin or ATP-synthases.