Discovering catalytic activities for pseudoenzymes

Ut Southwestern Medical Center, Dallas TX

Investigators

Abstract

PROJECT SUMMARY Numerous diseases stem from mutations or disturbances in enzyme activity. Comprehending the subsequent impact on substrates could yield vital mechanistic insights into disease mechanisms, potentially paving the way for interventions to treat these conditions. Most enzyme superfamilies contain catalytically inactive cousins known as pseudoenzymes, which resemble enzymes structurally but lack catalytic activity. However, my laboratory has discovered that some pseudokinases are catalytically active, catalyzing different chemical reactions than their active counterparts. This challenges the notion that all pseudoenzymes are catalytically inactive and suggests that they should be tested for alternative activities. Thus, a major goal of my research program in the next five years will be to determine whether pseudoenzymes from various enzyme superfamilies exhibit catalytic activity, potentially catalyzing novel chemical transformations. Uncovering unexpected post-translational modifications (PTMs) for pseudoenzymes presents several challenges. These include identifying candidate pseudoenzymes that are divergent members of the enzyme superfamily, pinpointing the specific substrate(s) undergoing modification, and identifying the PTM itself. To tackle these challenges, we have devised innovative strategies, including the development of a modular, proximity ligation method called SidBait. SidBait is a robust and modular platform for uncovering protein-protein and enzyme-substrate interactions. It has the potential to transform enzyme-substrate exploration, providing a dependable and economical strategy for pinpointing targets. This innovation could substantially enhance our understanding of enzyme and pseudoenzyme substrate interactions, increase the collection of recognized PTMs, and yield crucial mechanistic insights into human diseases. Importantly, pseudoenzymes are widespread in all major enzyme families throughout nature. Thus, assigning catalytic activities to pseudoenzymes has the potential to make a major impact in the field and fundamentally change the way we think about cellular signaling and regulation. I have assembled a team of diverse, enthusiastic, and dedicated trainees, which uniquely positions us to continue to make discoveries in this research area. Therefore, I am confident that the research program I have developed will uncover new biology, potentially leading to the development of innovative diagnostic tools or treatments for human diseases.