Oligosaccharyltransferases (OTases) are enzymes that catalyze the transfer of an oligosaccharide from a lipid carrier to an acceptor molecule, commonly a protein. OTases are classified as N-OTases and O-OTases, depending on the nature of the glycosylation reaction. The N-OTases catalyze the glycan transfer to amide groups in asparagines in a reaction named N-linked glycosylation. The O-OTases are responsible for protein O-linked glycosylation, which involves the attachment of glycans to hydroxyl groups of serine or threonine residues. Our lab focuses in the O-glycosylation process, which in some cases is mediated by the O-OTase PglL and results in the glycosylation of multiple proteins. Through its functional reconstitution in E. coli cells, we have shown that PglL works at the bacterial periplasm, and has the ability to transfer a variety of glycans to a protein acceptor, both in vivo and in vitro. The broad spectrum of glycans transferred is unprecedented for an OTase and may have an important impact on its applications in biotechnology, particularly the generation of novel conjugate vaccines and diagnostics. Here, we will discuss some of our recent advances in these two applied aspects. We also present novel data describing the O-glycosylation system recently identified in the “superbug” Acinetobacter baumannii, responsible for multiple outbreaks in hospitals around the world.
