New Method Developed to Investigate Protein Glycosylation Dynamics

Researchers at EMBL Heidelberg have developed a new method called DQGlyco to study glycosylation—the process where proteins are modified by carbohydrates. Their paper, published in Nature Structural and Molecular Biology, demonstrates the method's ability to analyze glycosylation with greater scale and resolution than previous approaches.

Proteins are essential for cellular function, and glycosylation alters their functions, affecting cell adhesion, motility, and communication. Traditional methods for studying glycosylation have been laborious and difficult, involving processes like enriching glycosylated proteins, which are time-consuming and expensive.

“So far, it's not been possible to do such studies on a systematic scale, in a quantitative fashion, and with high reproducibility,” said Mikhail Savitski, senior author of the study. “These are the challenges we managed to overcome with the new method.” 

The new method uses low-cost laboratory materials like functionalized silica beads to selectively enrich glycosylated proteins from biological samples.

Applying DQGlyco to brain tissue samples from mice, researchers identified over 150,000 glycosylated forms of proteins (proteoforms), an increase of over 25-fold compared to previous studies. This quantitative method allows researchers to compare differences between samples from different tissues or species.

DQGlyco also enables the study of microheterogeneity—where a protein part is modified by many sugar groups. “I think the widespread prevalence of microheterogeneity is something people had always assumed but that had never been clearly demonstrated, since you need to have enough coverage of glycosylated proteins to be able to make the statement,” said Mira Burtscher, another first author of the study

The team used DQGlyco to address biological questions, such as whether the gut microbiome had any effect on the glycosylation signatures they had observed in the brain. Interestingly, the team found that when compared to germ-free mice, i.e., mice grown in a sterile environment such that they completely lack any microbes in and on their body, mice colonized with different gut bacteria had different glycosylation patterns in the brain. The changed patterns were particularly apparent in proteins known to be important in neural functions, such as cognitive processing and axon growth. 

The team is also working toward applying the new method to answer more fundamental biological questions and to understand the functional role glycosylation plays in cells.