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Yorodumi- EMDB-71017: Cryo-EM map of the E. coli clamp loader DnaX-complex loading beta... -
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Open data
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Basic information
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| Title | Cryo-EM map of the E. coli clamp loader DnaX-complex loading beta-clamp onto 1-nt gapped DNA in state 2 conformer 2 with less bent DNA | ||||||||||||
Map data | EMReady2 improved | ||||||||||||
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Keywords | DNA replication / DNA damage repair / clamp loading complex / clamp beta / clamp loader DnaX-complex / REPLICATION / REPLICATION-DNA complex | ||||||||||||
| Function / homology | Function and homology informationDNA polymerase III, clamp loader complex / DNA clamp loader activity / DNA polymerase III complex / replisome / DNA strand elongation involved in DNA replication / DNA polymerase processivity factor activity / 3'-5' exonuclease activity / response to radiation / DNA-templated DNA replication / ribonucleoside triphosphate phosphatase activity ...DNA polymerase III, clamp loader complex / DNA clamp loader activity / DNA polymerase III complex / replisome / DNA strand elongation involved in DNA replication / DNA polymerase processivity factor activity / 3'-5' exonuclease activity / response to radiation / DNA-templated DNA replication / ribonucleoside triphosphate phosphatase activity / DNA-directed DNA polymerase / DNA-directed DNA polymerase activity / DNA replication / viral translational frameshifting / ATP hydrolysis activity / DNA binding / ATP binding / metal ion binding / identical protein binding / cytoplasm Similarity search - Function | ||||||||||||
| Biological species | ![]() | ||||||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 3.12 Å | ||||||||||||
Authors | Zheng F / Yao YN / Georgescu R / Lyu M / O'Donnell ME / Li H | ||||||||||||
| Funding support | United States, 3 items
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Citation | Journal: bioRxiv / Year: 2026Title: The DnaX clamp loader sharply bends DNA to load β-clamp at nicks and small gaps. Authors: Fengwei Zheng / Nina Y Yao / Roxana E Georgescu / Meinan Lyu / Michael E O'Donnell / Huilin Li / ![]() Abstract: DNA sliding clamps are essential for processive DNA synthesis in all domains of life and are loaded by ATP-dependent clamp loaders that recognize recessed 3' ends. How clamp loaders function at nicks ...DNA sliding clamps are essential for processive DNA synthesis in all domains of life and are loaded by ATP-dependent clamp loaders that recognize recessed 3' ends. How clamp loaders function at nicks and small ssDNA gaps-common intermediates during DNA repair-remains incompletely understood. Here, we show that the bacterial DnaX clamp loader employs a fundamentally different mechanism from its eukaryotic counterpart. Whereas eukaryotic RFC unwinds DNA at the recessed 3' end and stabilizes the 5'-dsDNA at a dedicated shoulder site, the bacterial DnaX-complex neither unwinds DNA nor stably binds the 5'-dsDNA in vitro. Instead, cryo-EM structures reveal that the β-clamp itself contains a conserved external DNA-binding site that enables sharp bending of gapped DNA by ~150°, promoting insertion of the 3'-dsDNA into the clamp. This DNA-bending mechanism allows efficient β-clamp loading at nicks and small gaps and reveals a distinct bacterial strategy for clamp loading. Because small DNA gaps are frequently associated with DNA damage, clamps loaded at these sites are likely important for DNA repair. | ||||||||||||
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Structure visualization
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Downloads & links
-EMDB archive
| Map data | emd_71017.map.gz | 124.7 MB | EMDB map data format | |
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| Header (meta data) | emd-71017-v30.xml emd-71017.xml | 29.8 KB 29.8 KB | Display Display | EMDB header |
| FSC (resolution estimation) | emd_71017_fsc.xml | 11.9 KB | Display | FSC data file |
| Images | emd_71017.png | 53.6 KB | ||
| Filedesc metadata | emd-71017.cif.gz | 7.8 KB | ||
| Others | emd_71017_additional_1.map.gz emd_71017_half_map_1.map.gz emd_71017_half_map_2.map.gz | 168.1 MB 165 MB 165 MB | ||
| Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-71017 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-71017 | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 9oyfMC ![]() 9oybC ![]() 9oycC ![]() 9oydC ![]() 9oyeC ![]() 9oygC ![]() 9oyhC ![]() 9oyiC ![]() 9oyjC ![]() 9oykC ![]() 9oylC ![]() 9oymC ![]() 9oynC M: atomic model generated by this map C: citing same article ( |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
| EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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| Related items in Molecule of the Month |
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Map
| File | Download / File: emd_71017.map.gz / Format: CCP4 / Size: 178 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||
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| Annotation | EMReady2 improved | ||||||||||||||||||||||||||||||||||||
| Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 0.828 Å | ||||||||||||||||||||||||||||||||||||
| Density |
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||
| Details | EMDB XML:
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-Supplemental data
-Additional map: Original map
| File | emd_71017_additional_1.map | ||||||||||||
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| Annotation | Original map | ||||||||||||
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| Density Histograms |
-Half map: half map B
| File | emd_71017_half_map_1.map | ||||||||||||
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| Annotation | half map B | ||||||||||||
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-Half map: half map A
| File | emd_71017_half_map_2.map | ||||||||||||
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| Annotation | half map A | ||||||||||||
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Sample components
+Entire : E. coli clamp loading complex
+Supramolecule #1: E. coli clamp loading complex
+Supramolecule #2: beta clamp bound to loader DnaX-complex
+Supramolecule #3: 1-nt gapped DNA substrate
+Macromolecule #1: DNA polymerase III subunit delta
+Macromolecule #2: DNA polymerase III subunit tau
+Macromolecule #3: DNA polymerase III subunit delta'
+Macromolecule #4: Beta sliding clamp
+Macromolecule #7: DNA polymerase III subunit psi
+Macromolecule #5: 1-nt gapped DNA template strand
+Macromolecule #6: 1-nt gapped DNA primer strand 1
+Macromolecule #8: 1-nt gapped DNA primer strand 2
+Macromolecule #9: ZINC ION
+Macromolecule #10: PHOSPHOTHIOPHOSPHORIC ACID-ADENYLATE ESTER
+Macromolecule #11: MAGNESIUM ION
-Experimental details
-Structure determination
| Method | cryo EM |
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Processing | single particle reconstruction |
| Aggregation state | particle |
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Sample preparation
| Buffer | pH: 7.5 |
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| Vitrification | Cryogen name: ETHANE |
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Electron microscopy
| Microscope | TFS KRIOS |
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| Image recording | Film or detector model: GATAN K3 (6k x 4k) / Average electron dose: 49.6 e/Å2 |
| Electron beam | Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN |
| Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Nominal defocus max: 1.6 µm / Nominal defocus min: 1.2 µm |
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Keywords
Authors
United States, 3 items
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Processing
FIELD EMISSION GUN


