Structural basis for a Polθ helicase small-molecule inhibitor revealed by cryo-EM.
Fumiaki ItoZiyuan LiLeonid MinakhinGurushankar ChandramoulyMrityunjay TyagiRobert BetschJohn J KraisBernadette TaberiUmeshkumar VekariyaMarissa L CalbertTomasz SkorskiNeil JohnsonXiaojiang S ChenRichard T PomerantzPublished in: Nature communications (2024)
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.
Keyphrases
- small molecule
- structural basis
- dna repair
- dna damage
- protein protein
- electronic health record
- induced apoptosis
- working memory
- emergency department
- gene expression
- cell proliferation
- young adults
- oxidative stress
- palliative care
- binding protein
- dna binding
- mass spectrometry
- transcription factor
- single cell
- artificial intelligence
- cell free