Periodic Reporting for period 3 - RECGLYCANMR (Breaking the limits in glycan recognition by NMR)
Berichtszeitraum: 2021-09-01 bis 2023-02-28
Sugars are everywhere, involved in processes related to energy storage, used as molecular frameworks for defining structures, and mediating interactions related to life and disease. Glycoscience aims at unravelling the role of glycans (carbohydrates, saccharides, or glycans) in systems of biological and biomedical interest and ultimately, in life. However, despite the demonstrated role of sugars as recognition entities, the exploitation of relevant sugar–protein interactions for pathological events is still far from its optimum. RECGLYCANMR is trying to answer many questions that remain open in the field. How do carbohydrate-binding-proteins (lectins) obtain their exquisite specificity? How is a complex glycan recognised, showing several chemically identical saccharides units and antennae? How is saccharide promiscuity towards diverse competing proteins modulated? Alternatively, how is competition versus one given lectin handled by the competing glycans? Is it a stochastic or thermodynamic matter? Both? The key question: is there any ‘sugar code’? In that case, is it now fully achieved? RECGLYCANMR uses nuclear magnetic resonance as major tool for disentangling, at the highest possible resolution, interaction events in which sugars are involved. Glycan recognition NMR studies have been till now constrained to in vitro methodologies. However, the selectivity of lectins versus glycans and the modulation of sugars’ promiscuity should likely be modulated by the environment. Indeed, the cell is a special one. Thus, RECGLYCANMR focuses on studying these recognition events in a context similar to the natural one: within the cell and at the cell surface. A crowded ambient exists in cell where viscosity is huge respect to water and there are many interacting entities.
RECGLYCANMR employs a multidisciplinary methodology that synergistically combines state-of-the-art chemical biology methods, in-cell and biophysics protocols under crowding conditions to provide solutions related to glycan molecular recognition and their involvement in numerous diseases.
RECGLYCANMR employs a multidisciplinary methodology that synergistically combines state-of-the-art chemical biology methods, in-cell and biophysics protocols under crowding conditions to provide solutions related to glycan molecular recognition and their involvement in numerous diseases.
One of the key challenges for assessing the composition of N-glycans and their interactions in intact glycoproteins under conditions similar to the physiological ones has been achieved by developing a robust NMR-based method to tackle this problem. A methodology to obtain 13C-labelled glycans in intact glycoproteins has allowed deducing the glycan composition of the IgE high-affinity receptor (FcεRIα), and the receptor binding domain (RBD) of the SARS-CoV2 spike glycoprotein. NMR protocols have been impolemented that have allowed deducing the recognition features of long‐chain multiantennae N‐glycans, including the conformational and interaction analysis of a sialylated N‐glycan, receptor of the hemagglutinin protein of pathogenic influenza viruses. Given the importance of 19F-molecules in drug discovery, a robust STD-NMR-based methodology has been developed to identify the recognition features of complex 19F-containing oligosaccharides versus different lectins of therapeutic interest.
From the basic perspective, a new methodology based on NMR has been presented to the scientific community to address the structure, dynamics, presentation and interactions of intact glycoproteins. From tha pplication side, this methodology has been employed to investigate the interactions of the receptor binding domain of the spike glycoprotein of SARS CoV2 with human lectins of our immune system. It is expected that different events related to disease involving glycans (cancer, influenza, COVID-19) will be understood at different levels of complexity, from the basic fundamental knowledge to specific applications.