9bh9

Human DNA polymerase theta helicase domain dimer bound to DNA in the microhomology aligning conformation

spinqualitylabelsall models 9bh9, resolution 3.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9bh9 is a 4 chain structure with sequence from Homo sapiens and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.5Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DPOLQ_HUMAN Has a DNA polymerase activity on nicked double-stranded DNA and on a singly primed DNA template. The enzyme activity is resistant to aphidicolin, and inhibited by dideoxynucleotides. Exhibites a single-stranded DNA-dependent ATPase activity. Could be involved in the repair of interstrand cross-links. Publication Abstract from PubMed DNA double-strand breaks occur daily in all human cells and must be repaired with high fidelity to minimize genomic instability. Deficiencies in high-fidelity DNA repair by homologous recombination lead to dependence on DNA polymerase theta, which identifies DNA microhomologies in 3' single-stranded DNA overhangs and anneals them to initiate error-prone double-strand break repair. The resulting genomic instability is associated with numerous cancers, thereby making this polymerase an attractive therapeutic target. However, despite the biomedical importance of polymerase theta, the molecular details of how it initiates DNA break repair remain unclear. Here, we present cryo-electron microscopy structures of the polymerase theta helicase domain bound to microhomology-containing DNA, revealing DNA-induced rearrangements of the helicase that enable DNA repair. Our structures show that DNA-bound helicase dimers facilitate a microhomology search that positions 3' single-stranded DNA ends in proximity to align complementary bases and anneal DNA microhomology. We characterize the molecular determinants that enable the helicase domain of polymerase theta to identify and pair DNA microhomologies to initiate mutagenic DNA repair, thereby providing insight into potentially targetable interactions for therapeutic interventions. Human polymerase theta helicase positions DNA microhomologies for double-strand break repair.,Zerio CJ, Bai Y, Sosa-Alvarado BA, Guzi T, Lander GC Nat Struct Mol Biol. 2025 Feb 28. doi: 10.1038/s41594-025-01514-8. PMID:40021738 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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