Download MendeleyDiscovery and Structural Optimization of 2-Hydrazinopyrimidin-4-one Analogs Inhibiting Human ADP-Ribosylhydrolase ARH3.
Parviainen, T.A.O., Duong, M.T.H., Paakkonen, J., Burdova, K., Kuttichova, B., Hanzlikova, H., Lehtio, L., Heiskanen, J.P.(2025) ACS Chem Biol 20: 2438-2450
- PubMed: 40952342 Search on PubMed
- DOI: https://doi.org/10.1021/acschembio.5c00461
- Primary Citation Related Structures:
9RFD, 9RFE - PubMed Abstract:
Poly-ADP-ribosylation at sites of DNA damage, catalyzed by PARP enzymes, activates the DNA damage response, chromatin remodeling, and DNA repair. The modification is reversed by two enzymes in humans: PARG, which efficiently hydrolyzes the poly-ADP-ribose chains, and ARH3, which is the key enzyme for removing the last proximal mono-ADP-ribose from serine residues. While inhibitor development has largely focused on PARPs and PARG, no potent and selective inhibitors for ARH3 are currently available. We optimized a FRET-based competition assay for ARH3 and carried out high-throughput screening of small-molecule inhibitors. One hit compound, 1 , with a potency of 22 μM was discovered, and through structure-activity relationship studies and synthesis, we improved its potency 10-fold to 2 μM (compound 27 , MDOLL-0286). We demonstrate that the compound inhibits ARH3's poly-ADP-ribose hydrolytic activity on cellular substrates. Intriguingly, it does not effectively inhibit the hydrolysis of mono-ADP-ribosylation from natural protein substrates. This is despite the fact that the cocrystal structure of compound 1 bound to ARH3 reveals its overlap with the enzyme's ADP-ribose binding site, agreeing with the competition in the FRET assay. The first experimental ARH3 inhibitor complex provides a valuable starting point for developing more potent chemical probes to study DNA damage response mechanisms in the future.
- Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, Oulu FI-90014, Finland.
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