Evidence for Distinct CoA Binding Sites in Nudt19 and Nudt7, Two Mammalian Nudix Hydrolases that Degrade Coenzyme A

Coenzyme (CoA) is an essential cofactor required for hundreds of metabolic processes as well as protein acetylation, a post‐translational modification that regulates gene expression and activity of thousands of cellular proteins. CoA levels are tightly regulated. In diabetic mice, loss of regulation and an abnormally high concentration of CoA drive excess glucose production and contribute to hyperglycemia. This phenotype is associated with constitutively low CoA degradation, a process that is emerging as an important mechanism for CoA regulation. Nudt7 and Nudt19 are two peroxisomal enzymes with CoA‐degrading activity, which are highly expressed in the liver and kidney, respectively. Two members of the Nudix hydrolase superfamily, Nud7 and Nudt19 both catalyze the Mg 2+ ‐dependent hydrolysis of free and acyl‐CoAs at the phosphodiester bond. Nudt19 (42 kDa) is larger than Nudt7 (27 kDa) and contains a unique 46–50‐residue insertion in the putative Mg 2+ ‐binding box of unknown function. Nudt7 accepts a wider range of CoA substrates compared to Nudt19. Limited information is available on the biochemical and regulatory properties of Nudt7 and Nudt19. Additionally, the involvement of these enzymes in regulation CoA levels in vivo has not been proven. We identified residues on both Nudt7 and Nudt19 that play an essential role in CoA and Mg 2+ binding. By screening selected metabolites, we discovered that chenodeoxycholic acid (CDCA) is a specific inhibitor of Nudt19 but not Nudt7. A Nudt19 mutant lacking the Nudix box insertion, as well as four chimeric Nudt7/Nudt19 proteins, were generated to investigate the contribution of the CoA binding motif and the unique Nudix box of Nudt19 to its sensitivity to CDCA inhibition and substrate specificity. Finally, we show that mice lacking Nudt7 exhibit elevated liver CoA in the fed state and mice lacking Nudt19 exhibit higher CoA levels in the kidneys. These data establish the importance of Nudt7‐ and Nudt19‐mediated degradation in the regulation of tissue CoA levels. Support or Funding Information This work was supported by West Virginia University's School of Medicine, (10020452.15.F2R226W) startup foundation funding, and National Institutes of Health Grant GM119528 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .