9BP9 image
Deposition Date 2024-05-07
Release Date 2024-08-28
Last Version Date 2024-08-28
Entry Detail
PDB ID:
9BP9
Title:
Human DNA polymerase theta helicase domain in complex with inhibitor AB25583, dimer form
Biological Source:
Source Organism:
Homo sapiens (Taxon ID: 9606)
Host Organism:
Method Details:
Experimental Method:
Resolution:
3.21 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:DNA polymerase theta
Gene (Uniprot):POLQ
Chain IDs:A, B (auth: C)
Chain Length:894
Number of Molecules:2
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation
Structural basis for a Pol theta helicase small-molecule inhibitor revealed by cryo-EM.
Nat Commun 15 7003 7003 (2024)
PMID: 39143110 DOI: 10.1038/s41467-024-51351-4

Abstact

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 IC50 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.

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Primary Citation of related structures