Research

Fungal Proton Pumps
A main focus of the group lies on primary active transport proteins from the P-type ATPase family. P-type ATPases are highly flexible multi-domain transporters that use energy from ATP hydrolysis for the specific transport of ions across cellular membranes. We are particularly interested in the ATPase with the smallest substrate of all, the H+-ATPase – or proton pump.

Pma1

Hexamers of the fungal proton pump visualised by cryo-EM.

It pumps single protons across the plasma membrane in plants and fungi and thereby creates the proton-motive force, which is vital for the organism i.e. by fueling vital nutrient uptake systems.In certain fungi, the proton pump forms hexamers of ~600 kDa.
We study the structural basis for proton transport process and its regulation using a variety of methods ans targets.
Due to the fact that the proton pump is essential for all fungi, this research provides an important framework for the development of novel antifungal medication.

Bacterial Membrane Proteins
We also work on various bacterial membrane proteins that could serve as targets for novel antibiotics, in an era where we are facing a massive threat by the emergence of multiresistant bacterial strains.

bacterial

Expression, purification and EM micrograph of a bacterial membrane protein, tagged with GFP.

Methodology
We use a set of state-of-the-art biochemical and biophysical methods, such as X-ray crystallography, electron microscopy, SAXS, CD Spectroscopy, FSEC, liposome reconstitution, transport and ATPase assays. Through successful collaborations we also work with nanodiscs, native mass spectrometry and structure-based drug discovery.

hp

Protein crystals (left) are irradiated with high intensity X-rays at a synchrotron to collect diffraction data (middle), which are analysed to generate a 3D electron density map that allows us to revel the position of every atom in the crystallised molecule (right).

 

Method Development

XFEL_Serca

Diffraction image of a P-type ATPase  microcrystal collected at an X-FEL source. (SLAC-LCLS, Stanford, USA)

We aim to advance the exploration and development of new methods for investigating membrane protein-lipid interactions and determining structures from small and/or poorly diffracting crystals.
Together with an international group of researchers, we were part of a pioneering study that successfully used an X-Ray Free Electron Laser (XFEL) to determine a crystal structure from native-source P-type ATPase microcrystals (Bublitz et al, 2015, IUCrJ 2(Pt4): 409-20.).