EMD-44765
Human DNA polymerase theta helicase domain in complex with inhibitor AB25583, dimer form
EMD-44765
Single-particle3.21 Å
Deposition: 07/05/2024Map released: 28/08/2024
Last modified: 28/08/2024
Sample Organism:
Homo sapiens
Sample: Human DNA polymerase theta helicase domain in complex with inhibitor AB25583
Fitted models: 9bp9
Raw data: EMPIAR-11711
Deposition Authors: Ito F
,
Li Z,
Chen XS
Sample: Human DNA polymerase theta helicase domain in complex with inhibitor AB25583
Fitted models: 9bp9
Raw data: EMPIAR-11711
Deposition Authors: Ito F
,
Li Z,
Chen XS
Structural 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 JJ ,
Taberi B,
Vekariya U,
Calbert M ,
Skorski T,
Johnson N ,
Chen XS ,
Pomerantz RT
(2024) Nat Commun , 15 , 7003 - 7003
,
Li Z,
Minakhin L,
Chandramouly G,
Tyagi M,
Betsch R,
Krais JJ ,
Taberi B,
Vekariya U,
Calbert M ,
Skorski T,
Johnson N ,
Chen XS ,
Pomerantz RT
(2024) Nat Commun , 15 , 7003 - 7003
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 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.
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.