Determining the Role of Nudt7 in the Regulation of Cellular CoA Levels and Metabolism

Coenzyme A (CoA) is an essential cofactor required for hundreds of metabolic processes. Because it is such a critical cofactor, CoA levels are tightly regulated. In the fasted state and in diabetic mice, the concentration of CoA increases dramatically in the liver. This phenotype is associated with constitutively low CoA degradation, a process that is emerging as a potentially important mechanism for CoA regulation. Nudt7 and Nudt19 are two mammalian peroxisomal enzymes with CoA-degrading activity, which are highly expressed in the liver and kidney, respectively. Limited information is available on the biochemistry of Nudt7 and Nudt19; the structural basis for their distinct features and the extent to which Nudt7 contributes to maintaining homeostatic CoA levels in vivo are currently unknown. We used a combination of techniques including mutagenesis, molecular modeling, and enzymatic assays on purified proteins, plus metabolomics and measurement of fatty acid oxidation in whole tissue homogenates and intact hepatocytes to: 1) characterize the biochemical, structural, and regulatory properties of Nudt7 and Nudt19 and 2) determine the effects that manipulations of Nudt7 expression have on CoA levels and lipid metabolism in mouse liver. This research establishes the importance of Nudt7-dependent CoA degradation in the regulation of select acyl-CoA species and the output of peroxisomal metabolic pathways such as bile acid synthesis and peroxisomal fatty acid oxidation.