Download MendeleyStructural basis for a Pol theta helicase small-molecule inhibitor revealed by cryo-EM.
Ito, F., Li, Z., Minakhin, L., Chandramouly, G., Tyagi, M., Betsch, R., Krais, J.J., Taberi, B., Vekariya, U., Calbert, M., Skorski, T., Johnson, N., Chen, X.S., Pomerantz, R.T.(2024) Nat Commun 15: 7003-7003
- PubMed: 39143110
- DOI: https://doi.org/10.1038/s41467-024-51351-4
- Primary Citation of Related Structures:
9BP9, 9BPA - PubMed Abstract:
DNA polymerase theta (Polθ) is a DNA helicase-polymerase protein that facilitates DNA repair and is synthetic lethal with homology-directed repair (HDR) factors. Thus, Polθ is a promising precision oncology drug-target in HDR-deficient cancers. Here, we characterize the binding and mechanism of action of a Polθ helicase (Polθ-hel) small-molecule inhibitor (AB25583) using cryo-EM. AB25583 exhibits 6 nM IC 50 against Polθ-hel, selectively kills BRCA1/2-deficient cells, and acts synergistically with olaparib in cancer cells harboring pathogenic BRCA1/2 mutations. Cryo-EM uncovers predominantly dimeric Polθ-hel:AB25583 complex structures at 3.0-3.2 Å. The structures reveal a binding-pocket deep inside the helicase central-channel, which underscores the high specificity and potency of AB25583. The cryo-EM structures in conjunction with biochemical data indicate that AB25583 inhibits the ATPase activity of Polθ-hel helicase via an allosteric mechanism. These detailed structural data and insights about AB25583 inhibition pave the way for accelerating drug development targeting Polθ-hel in HDR-deficient cancers.
Organizational Affiliation:
Molecular and Computational Biology, Department of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California, CA, 90089, USA.
