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Yorodumi- PDB-9c5q: Human DNA polymerase theta helicase domain in microhomology annea... -
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Basic information
| Entry | Database: PDB / ID: 9c5q | |||||||||
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| Title | Human DNA polymerase theta helicase domain in microhomology annealed state 2, dimer form | |||||||||
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Keywords | TRANSFERASE/DNA / DNA repair / helicase / ATPase / TRANSFERASE-DNA complex | |||||||||
| Function / homology | Function and homology informationdouble-strand break repair via alternative nonhomologous end joining / HDR through MMEJ (alt-NHEJ) / single-stranded DNA helicase activity / replication fork processing / mitochondrial nucleoid / site of DNA damage / 5'-deoxyribose-5-phosphate lyase activity / error-prone translesion synthesis / negative regulation of double-strand break repair via homologous recombination / somatic hypermutation of immunoglobulin genes ...double-strand break repair via alternative nonhomologous end joining / HDR through MMEJ (alt-NHEJ) / single-stranded DNA helicase activity / replication fork processing / mitochondrial nucleoid / site of DNA damage / 5'-deoxyribose-5-phosphate lyase activity / error-prone translesion synthesis / negative regulation of double-strand break repair via homologous recombination / somatic hypermutation of immunoglobulin genes / DNA helicase activity / base-excision repair / protein homooligomerization / RNA-directed DNA polymerase / RNA-directed DNA polymerase activity / double-strand break repair / site of double-strand break / DNA helicase / DNA-directed DNA polymerase / damaged DNA binding / DNA-directed DNA polymerase activity / DNA repair / DNA damage response / chromatin binding / magnesium ion binding / Golgi apparatus / ATP hydrolysis activity / nucleoplasm / ATP binding / identical protein binding / nucleus / cytosol Similarity search - Function | |||||||||
| Biological species | Homo sapiens (human) | |||||||||
| Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.1 Å | |||||||||
Authors | Ito, F. / Li, Z. / Chen, X.S. | |||||||||
| Funding support | United States, 2items
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Citation | Journal: Nat Commun / Year: 2025Title: Structural basis for Polθ-helicase DNA binding and microhomology-mediated end-joining. Authors: Fumiaki Ito / Ziyuan Li / Leonid Minakhin / Htet A Khant / Richard T Pomerantz / Xiaojiang S Chen / ![]() Abstract: DNA double-strand breaks (DSBs) present a critical threat to genomic integrity, often precipitating genomic instability and oncogenesis. Repair of DSBs predominantly occurs through homologous ...DNA double-strand breaks (DSBs) present a critical threat to genomic integrity, often precipitating genomic instability and oncogenesis. Repair of DSBs predominantly occurs through homologous recombination (HR) and non-homologous end joining (NHEJ). In HR-deficient cells, DNA polymerase theta (Polθ) becomes critical for DSB repair via microhomology-mediated end joining (MMEJ), also termed theta-mediated end joining (TMEJ). Thus, Polθ is synthetically lethal with BRCA1/2 and other HR factors, underscoring its potential as a therapeutic target in HR-deficient cancers. However, the molecular mechanisms governing Polθ-mediated MMEJ remain poorly understood. Here we present a series of cryo-electron microscopy structures of the Polθ helicase domain (Polθ-hel) in complex with DNA containing different 3'-ssDNA overhangs. The structures reveal the sequential conformations adopted by Polθ-hel during the critical phases of DNA binding, microhomology searching, and microhomology annealing. The stepwise conformational changes within the Polθ-hel subdomains and its functional dimeric state are pivotal for aligning the 3'-ssDNA overhangs, facilitating the microhomology search and subsequent annealing necessary for DSB repair via MMEJ. Our findings illustrate the essential molecular switches within Polθ-hel that orchestrate the MMEJ process in DSB repair, laying the groundwork for the development of targeted therapies against the Polθ-hel. #1: Journal: bioRxiv / Year: 2024 Title: Structural Basis for Polθ-Helicase DNA Binding and Microhomology-Mediated End-Joining. Authors: Fumiaki Ito / Ziyuan Li / Leonid Minakhin / Htet A Khant / Richard T Pomerantz / Xiaojiang S Chen / ![]() Abstract: DNA double-strand breaks (DSBs) present a critical threat to genomic integrity, often precipitating genomic instability and oncogenesis. Repair of DSBs predominantly occurs through homologous ...DNA double-strand breaks (DSBs) present a critical threat to genomic integrity, often precipitating genomic instability and oncogenesis. Repair of DSBs predominantly occurs through homologous recombination (HR) and non-homologous end joining (NHEJ). In HR-deficient cells, DNA polymerase theta (Polθ) becomes critical for DSB repair via microhomology-mediated end joining (MMEJ), also termed theta-mediated end joining (TMEJ). Thus, Polθ is synthetically lethal with BRCA1/2 and other HR factors, underscoring its potential as a therapeutic target in HR-deficient cancers. However, the molecular mechanisms governing Polθ-mediated MMEJ remain poorly understood. Here we present a series of cryo-electron microscopy structures of the Polθ helicase domain (Polθ-hel) in complex with DNA containing 3'-overhang. The structures reveal the sequential conformations adopted by Polθ-hel during the critical phases of DNA binding, microhomology searching, and microhomology annealing. The stepwise conformational changes within the Polθ-hel subdomains and its functional dimeric state are pivotal for aligning the 3'-overhangs, facilitating the microhomology search and subsequent annealing necessary for DSB repair via MMEJ. Our findings illustrate the essential molecular switches within Polθ-hel that orchestrate the MMEJ process in DSB repair, laying the groundwork for the development of targeted therapies against the Polθ-hel. | |||||||||
| History |
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Structure visualization
| Structure viewer | Molecule: Molmil Jmol/JSmol |
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Downloads & links
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Download
| PDBx/mmCIF format | 9c5q.cif.gz | 319.5 KB | Display | PDBx/mmCIF format |
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| PDB format | pdb9c5q.ent.gz | 249.7 KB | Display | PDB format |
| PDBx/mmJSON format | 9c5q.json.gz | Tree view | PDBx/mmJSON format | |
| Others | Other downloads |
-Validation report
| Summary document | 9c5q_validation.pdf.gz | 1.3 MB | Display | wwPDB validaton report |
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| Full document | 9c5q_full_validation.pdf.gz | 1.3 MB | Display | |
| Data in XML | 9c5q_validation.xml.gz | 56.3 KB | Display | |
| Data in CIF | 9c5q_validation.cif.gz | 84.6 KB | Display | |
| Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/c5/9c5q ftp://data.pdbj.org/pub/pdb/validation_reports/c5/9c5q | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 45218MC ![]() 8w0aC ![]() 9asjC ![]() 9askC ![]() 9aslC M: map data used to model this data C: citing same article ( |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
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Assembly
| Deposited unit | ![]()
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Components
| #1: DNA chain | Mass: 4243.748 Da / Num. of mol.: 2 / Source method: obtained synthetically / Source: (synth.) Homo sapiens (human)#2: Protein | Mass: 92089.797 Da / Num. of mol.: 2 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLQ, POLH / Production host: ![]() References: UniProt: O75417, DNA helicase, DNA-directed DNA polymerase, RNA-directed DNA polymerase Has protein modification | Y | |
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-Experimental details
-Experiment
| Experiment | Method: ELECTRON MICROSCOPY |
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| EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
| Component | Name: Human DNA polymerase theta helicase domain in microhomology annealed state 2, dimer form Type: COMPLEX / Entity ID: all / Source: MULTIPLE SOURCES |
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| Molecular weight | Value: 0.253 MDa / Experimental value: NO |
| Source (natural) | Organism: Homo sapiens (human) |
| Source (recombinant) | Organism: ![]() |
| Buffer solution | pH: 7.5 |
| Specimen | Conc.: 1 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
| Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 277 K |
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Electron microscopy imaging
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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| Microscopy | Model: TFS KRIOS |
| Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
| Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 105000 X / Nominal defocus max: 2000 nm / Nominal defocus min: 600 nm / Cs: 2.7 mm / C2 aperture diameter: 50 µm |
| Image recording | Average exposure time: 3.5 sec. / Electron dose: 65 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 1 / Num. of real images: 10005 |
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Processing
| EM software | Name: EPU / Version: 3.5.0 / Category: image acquisition |
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| CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION |
| Particle selection | Num. of particles selected: 3203827 |
| Symmetry | Point symmetry: C2 (2 fold cyclic) |
| 3D reconstruction | Resolution: 3.1 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 78928 / Num. of class averages: 1 / Symmetry type: POINT |
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Homo sapiens (human)
United States, 2items
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FIELD EMISSION GUN