ADPribosylation and Ubiquitination; post-translational interplay

Post-translational modification of proteins is essential in regulating proper cellular homeostasis. The attachment and removal of the small protein Ubiquitin (Ub) is amongst others involved in regulating immune response, cell cycle progression and proteasome mediated protein degradation. The (de)conjugation of adenosine-di-phosphate ribose (ADPr) on the other hand is essential in regulating DNA damage responses and apoptosis. ADPribosylation and ubiquitination both dictate a highly complex signaling code and intriguingly these two PTM systems also communicate, as Ub was recently found to be ADPribosylated on multiple different positions. This new layer of controlling ubiquitination plays important roles in intracellular bacterial replication, DNA damage repair and tumor development. Understanding this fascinating post-translational interplay and the role the different UbADPr-isotypes play in cell biology is crucial to develop novel strategies for therapeutic intervention in diseases such as infection diseases and cancers. What are the mechanisms, biochemical scope of protein-protein interactions, cell biological consequences and differences between these non-studied UbADPr linkages? I propose to study the entire system of dynamic ADPribosylation of Ub and explain the molecular details of the (de)conjugating enzymes, explore the cell biological networks involved and exploit the key enzymes for inhibitor discovery en-route to future therapeutic intervention. I will develop novel chemical methodologies and create a set of new substrates, activity-based probes and assay reagents and use them to profile specificity and preferences of the involved enzymes, study the interactions and pathways in cells and screen for small molecule inhibitors. Using my expertise in protein synthesis and chemical- and structural biology I aim to unveil the details of this until now poorly studied, but crucial, hidden layer of post-translational interplay in an unbiased manner.