Development of tools and methods for studying glycan processing proteins in living systems

Carbohydrates are a class of biomolecules present in all domains of life that provide energy for cellular processes, afford structural support, and take part in molecular recognition and signalling. Given the ubiquity of carbohydrates in living systems, gaining an improved understanding of the proteins that process them – glycosyl transferases, glycoside hydrolases, lectins, and sugar transporters – is of key interest. Compared to in vitro assays, few live-cell or in vivo assays of carbohydrate-processing proteins have been developed, despite the wealth of knowledge that they provide. This discrepancy is largely due to the difficulties associated with live-cell and in vivo examination of protein function, namely issues of substrate selectivity, sensitivity, reactivity, and cell permeability. This thesis aims to develop substrates and methods to study two carbohydrate-processing proteins: human O-GlcNAcase, a glycoside hydrolase involved in Alzheimer’s disease, cancer, and the stabilization of nascent proteins; and bacterial AmpG, a sugar transporter implicated in β-lactam antibiotic resistance. In doing so, I hope to not only provide insight into the function of these proteins, but to also lay a foundation for live-cell or in vivo study of these and related proteins in the years to come.