Identification and characterization of human mevalonate kinase inhibitors

Abstract

The mevalonate pathway is responsible for the synthesis of isoprenoids, which are essential for various biological activities, such as cell signaling and membrane function. Mevalonate kinase (MK) is a critical enzyme in this pathway, converting mevalonic acid (MVA) to mevalonate-5- phosphate (M-5-P) with ATP as a phosphoryl donor. Mutations in the MVK gene, which encodes MK, can cause mevalonate kinase deficiency, an inborn error of metabolism characterized by severe, recurrent inflammation. Previous research has shown that farnesyl pyrophosphate (FPP), a downstream metabolite of the mevalonate pathway, inhibits MK by blocking its ATP binding site. Interestingly, FPP also inhibits FPP synthase, the enzyme that produces FPP. These observations provide evidence for multilayered regulation of the mevalonate pathway, where the single feedback inhibitor FPP targets multiple enzymatic steps. In this thesis, I verified the hypothesis that analogs of FPP that can inhibit FPP synthase could also inhibit MK. Using an enzyme-coupled spectrophotometric assay, I identified several phosphonate compounds that can inhibit MK with nanomolar potency. Further analysis revealed features of these compounds that correlate with their inhibitory activity. The mode of inhibition was also determined for representative compounds. To better understand how MK interacts with its ligands, I have commenced X-ray crystallography studies. The inhibitor compounds identified in this study may serve as a useful tool for future research, for example, in evaluating MK as a new therapeutic target and advancing our understanding of mevalonate pathway regulation.