Molecular mechanisms of O-GlcNAc signalling. (360G-Wellcome-087590_Z_08_A)

Post-translational modification of eukaryotic protein serines/threonines with N-acetylglucosamine (O-GlcNAc) was discovered 20 years ago. Subsequent work has shown that O-GlcNAcylation is regulated by a tranferase (OGT) and a hydrolase (OGA), both single, essential genes, conserved from C. elegans to humans, and that a plethora of proteins in the nucleoplasm are O-GlcNAcylated. Excitingly, there are examples of O-GlcNAcylation having interplay with phosphorylation, including competition for the same serines/threonines, giving rise to the Yin-Yang hypothesis , that proposes O-GlcNAc as a global, glucose dependent, mechanism to control protein phosphorylation. I aim to use a multi-disciplinary approach to uncover the molecular mechanisms governing O-GlcNAcylation and its importance in a number of signal transduction pathways. Capitalising on a significant body or preliminary data, the aims are to: 1) Synthesize/discover OGA/OGT inhibitors and substrate analogues, including glycopeptide s. 2) Determine the structures of human OGA/OGT, including inhibitor/protein substrate complexes and probe mechanism/specificity with mutagenesis and in vitro assays. 3) Understand the effect of O-GlcNAc on phosporylation/activity on key signalling proteins in pathways involve in the insulin response, neuronal development and energy stasis. 4) Investigate whether orthologues of these enzymes in pathogenic bacteria are involved in prokaryotic O-GlcNAc and/or are virulence factors targetting ho st proteins.