Mass Screening of Metabolites as Human Glutamine Synthetase Regulators
Ryan Leung, Rowan Jacobs
Department of Biology
Faculty Supervisor: Eric Greene
Frequently, metabolic enzymes must respond to changes in cellular metabolic state at the protein-level. Protein-metabolite interactions are one way that enzyme activity can be tuned and it has been recently appreciated that these interactions are pervasive throughout central carbon metabolism. However, protein-metabolite interactions in nitrogen metabolism has not been fully explored. Glutamine synthetase (GS) is a critical enzyme in nitrogen metabolism, playing a central role in cellular growth and detoxification. Its overactivity is implicated in cancer and its dysfunction contributes to hepatic encephalopathy and Alzheimer’s disease. Despite its importance, there is scant evidence of protein-level enzyme regulation, largely due to the lack of identified allosteric regulators that could selectively modulate its activity. This study aims to uncover allosteric regulators of GS through a activity screening approach using a library of over 800 endogenous metabolites. Identified regulators will be characterized for their steady-state inhibition mechanisms and structurally resolved via cryo-electron microscopy (cryo-EM) to locate their binding sites. By focusing on protein-metabolite regulation of GS, this work will provide a metabolite-GS interaction map that underlies GS regulation. Furthermore, this work may uncover allosteric binding sites on GS which would potentially expand the mechanistic scope of GS inhibitors beyond orthosteric inhibitors which are the only available to date.