Identification of Potent ADCK3 Inhibitors through Structure-Based Virtual Screening

ADCK3 is a member of the UbiB family of atypical protein kinases in humans, with homologues in archaea, bacteria, and eukaryotes. In lieu of protein kinase activity, ADCK3 plays a role in the biosynthesis of coenzyme Q10 (CoQ10), and inactivating mutations can cause a CoQ10 deficiency and ataxia. However, the exact functions of ADCK3 are still unclear, and small-molecule inhibitors could be useful as chemical probes to elucidate its molecular mechanisms. In this study, we applied structure-based virtual screening (VS) to discover a novel chemical series of ADCK3 inhibitors. Through extensive structural analysis of the active-site residues, we developed a pharmacophore model and applied it to a large-scale VS. Out of ∼170,000 compounds virtually screened, 800 top-ranking candidate compounds were selected and tested in both ADCK3 and p38 biochemical assays for hit validation. In total, 129 compounds were confirmed as ADCK3 inhibitors, and among them, 114 compounds are selective against p38, which was used as a counter-target. Molecular dynamics (MD) simulations were then conducted to predict the binding modes of the most potent compounds within the ADCK3 active site. Through metadynamics analysis, we successfully detected the key amino acid residues that govern intermolecular interactions. The findings provided in this study can serve as a promising starting point for drug development.