Chemical and biochemical strategies to explore the substrate recognition of O-GlcNAc cycling enzymes.

The O-linked N-acetylglucosamine (O-GlcNAc) modification is an essential component in cell regulation. A single pair of human enzymes conducts this modification dynamically on a broad variety of proteins: O-GlcNAc transferase (OGT) adds the GlcNAc residue and O-GlcNAcase (OGA) hydrolyzes it. This modification is dysregulated in many diseases, but its exact role on particular substrates remains unclear. In addition, no apparent sequence motif was found in the modified proteins and the factors controlling the substrate specificity of OGT and OGA are largely unknown. In this concept, we will discuss recent developments of chemical and biochemical methods toward addressing the challenge of OGT and OGA substrate recognition. We hope the new concept and knowledge from these studies will promote research in this area to advance understanding of O-GlcNAc regulation in health and disease.