
Exploring glycan-protein interactions and post-translational modifications by NMR
Mário Schubert, Dept. of Molecular Biology, University of Salzburg, Wien
Host: Eurico Cabrita, UCIBIO-NOVA
ZOOM link: https://bit.ly/GuestSeminarsUCIBIO
ID da reunião: 865 7786 0516
Senha: 805165
Abstract: Protein-carbohydrate recognition is central for understanding the function of glycans, either as part of glycoproteins or glycolipids. As X-ray crystallography and electron microscopy occasionally struggle in obtaining high-resolution 3D structures of such interactions, we developed a robust approach for determining 3D structures of a protein recognizing a glycoepitope with nuclear magnetic resonance (NMR) spectroscopy. As a proof of principle, I will present the complex structure of a tight interaction (Kd = 1μM) and of a weak interaction (Kd = 0.3 mM). The first example is a fungal defense protein recognizing α1,3-fucosylated N-glycan cores - a motif that is abundant in predators. The second example is the lectin domain of the human receptor Siglec-8 in complex with a sulfated form of sialyl Lex.
In addition, we focus on the characterization of posttranslational modifications by NMR spectroscopy using model peptides, model proteins (mostly protein therapeutics) and forced-degradation studies together with 2D NMR spectra measured under denaturing conditions. The technique is not limited by the protein size; we demonstrated its application to full-length antibodies and Fc-fusion proteins. The so far detectable modifications are products of oxidation, deamidation, and backbone cleavage but also abundant glycosylation species. To aid the identification of unknown oligosaccharides in untargeted glycomics using NMR correlations and chemical shifts, we developed a powerful search algorithm, which we make available as the web application GlycoNMRSearch.
Short CV: Dr. Mario Schubert is an NMR spectroscopist and chemist. His main interest lies in method development extending the limits NMR spectroscopy for applications in biosciences with a focus on glycobiology and posttranslational modifications.
Dr. Schubert studied Chemistry at the Free University of Berlin (Germany) and worked as Diploma student in the group of Prof. J. Elguero (CSIC, Madrid, Spain) and Prof. H.H. Limbach (1997). He then joined the group of Prof. H. Oschkinat at the FMP-Berlin as PhD student. After a postdoctorate (Alexander von Humboldt) at the UBC in Vancouver (Canada) with Prof. L.P. McIntosch. In 2004 he moved to the ETH-Zürich, first joining the group of Prof. B.H. Meier and then the group of Prof. F. Allain. He started as PI of research projects at ETH Zürich, Switzerland in 2008 with a Sinergia grant applying methodology developed for protein-RNA recognition to protein-carbohydrate recognition. Since 2014, he is a permanent researcher at Salzburg University in Austria.