Studying bacterial glycans with azidosugars and bioorthogonal chemistry

Bacterial glycans are intriguing molecular targets due to their prominent location on the bacterial cell envelope and their important roles in bacterial fitness and pathogenesis. However, the study of bacterial glycans is challenging due to the structural complexity and compositional diversity of these structures. Metabolic glycan labeling offers a tractable approach to label and study bacterial glycans. In this two-step method, bacteria process unnatural sugars bearing azides into cellular glycans, and then azide-labeled glycans undergo bioorthogonal chemistry to covalently deliver detection reagents for downstream analysis of cellular glycans. This methods paper focuses specifically on protocols developed to metabolically label glycoproteins in the gastric pathogen Helicobacter pylori and metabolically inhibit their biosynthesis. The protocols presented here can be readily adapted for the study of glycans in a range of bacteria and should provide important resources for the bacterial glycoscience community.