Research groupDepartment

Hartmut Oschkinat

NMR-Supported Structural Biology

Portrait

The Oschkinat lab focuses on the structural characterisation of protein-protein interactions responsible for the reception and transduction of signals in biological systems. We are interested in protein domains which recognise specific peptides and in membrane integrated receptors and receptor-ligand complexes.


Investigating highly complex structural information

Magic-angle spinning (MAS) solid-state NMR spectroscopy provides high-resolution structural information on heterogeneous samples, independent of the molecular weight of the investigated proteins, carbohydrates or chains of nucleic acids. It is an attractive method for structural investigations on “difficult” systems such as small proteins embedded in lipid bilayers, large polydisperse complexes or biological macromolecules in their natural environment such as in live biofilms. NMR provides a direct view of protons and connected exchange processes, and allows distinctions to be made between rapidly interconverting structural states on the basis of their characteristic chemical shifts. Furthermore, it enables a quantification of all structural states present. In a pharmacological context, we carry out investigations within the “real space” of a cell, capitalizing on a 20-100-fold increase in the signal-to-noise ratio afforded by the use of dynamic nuclear polarization (DNP). For this purpose, we have been improving and testing DNP methods on biological samples. Furthermore, we apply very fast MAS for studying protein structure. At spinning frequencies of 100,000 rotations per second, high-resolution proton spectra can be obtained using a minimal sample quantity. Fast MAS at 100 kHz was used, for instance, to study the binding of small molecules to the neonatal Fc receptor. Finally, we investigate large dynamic and polydisperse protein systems involved in protein homeostasis, including small heat shock proteins, biological systems undergoing phase separation, and biofilms.

 

Research Focus

The main focus of our group is the development of solid-state magic-angle spinning (MAS) NMR methodology as a routine tool for biological studies, in particular for structural characterisation of protein-protein interactions that are responsible for the reception and transduction of signals. This research focuses traditionally on membrane integrated proteins and receptor-ligand complexes.

In recent years a new method for signal enhancement called dynamic nuclear polarisation (DNP) was established and its value tested in structure determination and metabolomic projects. Using DNP, the nascent peptide chain in the tunnel of the ribosome was investigated, and the nature of black deposits in cartilage of Alkaptonuria patients, who suffer from impaired tyrosine degradation. Recently, we started a set of new projects on membrane proteins and inositol lipids in their actual membranes, and on live biofilms. Furthermore, we have started a project on the principles underlying liquid-liquid phase separation, with the protein FUS as an example. Our aim is to provide quantitative information as to individual interactions, responsible for establishing the dense phase and the structural characterization of such interactions. Furthermore, we are investigating proton flows and proton dynamics to understand protein function, funded by the SFB 1078.

Protein Expression and NMR Sample Preparation

Contact Office

Andrea Steuer

Secretary, Oschkinat Group


Research Section

Structural Biology