Coenzyme A (CoA) biosynthesis is controlled by the four isoforms of the rate-limiting enzyme pantothenate kinase (PANK), whose tissue expression and subcellular localization regulate CoA homeostasis. Pantazines are positive allosteric modulators of PANK that increase cellular CoA levels by disrupting feedback inhibition by acyl-CoA esters. In this study, a structure-guided design was used to modify the Pantazine scaffold near the ATP-binding site to address metabolic liabilities of earlier leads. Replacement of a metabolically labile cyclopropyl group with a sulfonamide introduced a new hydrogen-bonding interaction with the γ-phosphate of ATP in the PANK3•ATP•Pantazine complex. This interaction improved ligand affinity, solubility, and metabolic stability. Analysis of isoform-specific inhibition revealed that cellular CoA elevation correlates with the difference in affinity between PANK3 and PANK1β, defining an "activation window" for CoA induction. Lead sulfonamide Pantazines were metabolically stable and increased hepatic CoA levels, supporting their potential for treating metabolic CoA deficiencies.
Coker et al. (Mon,) studied this question.