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Open data
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Basic information
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| Title | local refinement of MCM_ATP_dsDNA | |||||||||
 Map data | local refinement of MCM_ATP_dsDNA | |||||||||
 Sample | 
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 Keywords | Helicase / Replication / HYDROLASE | |||||||||
| Biological species | ![]()  Thermococcus kodakarensis (archaea) | |||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 3.57 Å | |||||||||
 Authors | Ma J / Yi G / Ye M / MacGregor-Chatwin C / Sheng Y / Lu Y / Li M / Gilbert RJC / Zhang P | |||||||||
| Funding support |   United Kingdom, 2 items 
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 Citation |  Journal: Nat Commun / Year: 2024Title: Open architecture of archaea MCM and dsDNA complexes resolved using monodispersed streptavidin affinity CryoEM. Authors: Jianbing Ma / Gangshun Yi / Mingda Ye / Craig MacGregor-Chatwin / Yuewen Sheng / Ying Lu / Ming Li / Qingrong Li / Dong Wang / Robert J C Gilbert / Peijun Zhang /     ![]() Abstract: The cryo-electron microscopy (cryoEM) method has enabled high-resolution structure determination of numerous biomolecules and complexes. Nevertheless, cryoEM sample preparation of challenging ...The cryo-electron microscopy (cryoEM) method has enabled high-resolution structure determination of numerous biomolecules and complexes. Nevertheless, cryoEM sample preparation of challenging proteins and complexes, especially those with low abundance or with preferential orientation, remains a major hurdle. We developed an affinity-grid method employing monodispersed single particle streptavidin on a lipid monolayer to enhance particle absorption on the grid surface and alleviate sample exposure to the air-water interface. Using this approach, we successfully enriched the Thermococcus kodakarensis mini-chromosome maintenance complex 3 (MCM3) on cryoEM grids through biotinylation and resolved its structure. We further utilized this affinity method to tether the biotin-tagged dsDNA to selectively enrich a stable MCM3-ATP-dsDNA complex for cryoEM structure determination. Intriguingly, both MCM3 apo and dsDNA bound structures exhibit left-handed open spiral conformations, distinct from other reported MCM structures. The large open gate is sufficient to accommodate a dsDNA which could potentially be melted. The value of mspSA affinity method was further demonstrated by mitigating the issue of preferential angular distribution of HIV-1 capsid protein hexamer and RNA polymerase II elongation complex from Saccharomyces cerevisiae.  | |||||||||
| History | 
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Structure visualization
| Supplemental images | 
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Downloads & links
-EMDB archive
| Map data |  emd_38123.map.gz | 11.1 MB |  EMDB map data format | |
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| Header (meta data) |  emd-38123-v30.xml emd-38123.xml | 12.8 KB 12.8 KB  | Display Display  |  EMDB header | 
| Images |  emd_38123.png | 79.4 KB | ||
| Filedesc metadata |  emd-38123.cif.gz | 4 KB | ||
| Others |  emd_38123_half_map_1.map.gz emd_38123_half_map_2.map.gz | 200.7 MB 200.7 MB  | ||
| Archive directory |  http://ftp.pdbj.org/pub/emdb/structures/EMD-38123 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-38123 | HTTPS FTP  | 
-Validation report
| Summary document |  emd_38123_validation.pdf.gz | 840.1 KB | Display |  EMDB validaton report | 
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| Full document |  emd_38123_full_validation.pdf.gz | 839.7 KB | Display | |
| Data in XML |  emd_38123_validation.xml.gz | 15.5 KB | Display | |
| Data in CIF |  emd_38123_validation.cif.gz | 18.4 KB | Display | |
| Arichive directory |  https://ftp.pdbj.org/pub/emdb/validation_reports/EMD-38123 ftp://ftp.pdbj.org/pub/emdb/validation_reports/EMD-38123 | HTTPS FTP  | 
-Related structure data
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Links
| EMDB pages |  EMDB (EBI/PDBe) /  EMDataResource | 
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Map
| File |  Download / File: emd_38123.map.gz / Format: CCP4 / Size: 216 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||
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| Annotation | local refinement of MCM_ATP_dsDNA | ||||||||||||||||||||||||||||||||||||
| Projections & slices | Image control
 
 Images are generated by Spider.  | ||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 0.932 Å | ||||||||||||||||||||||||||||||||||||
| Density | 
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||
| Details | EMDB XML: 
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-Supplemental data
-Half map: half map A of local refinement of MCM ATP dsDNA
| File | emd_38123_half_map_1.map | ||||||||||||
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| Annotation | half map A of local refinement of MCM_ATP_dsDNA | ||||||||||||
| Projections & Slices | 
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| Density Histograms | 
-Half map: half map B of local refinement of MCM ATP dsDNA
| File | emd_38123_half_map_2.map | ||||||||||||
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| Annotation | half map B of local refinement of MCM_ATP_dsDNA | ||||||||||||
| Projections & Slices | 
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| Density Histograms | 
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Sample components
-Entire : MCM homohexamer in complex with dsDNA in presence of ATP
| Entire | Name: MCM homohexamer in complex with dsDNA in presence of ATP | 
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| Components | 
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-Supramolecule #1: MCM homohexamer in complex with dsDNA in presence of ATP
| Supramolecule | Name: MCM homohexamer in complex with dsDNA in presence of ATP type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1  | 
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| Source (natural) | Organism: ![]()  Thermococcus kodakarensis (archaea) | 
-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: 7.8 | 
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| Vitrification | Cryogen name: ETHANE | 
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Electron microscopy
| Microscope | FEI TITAN KRIOS | 
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| Image recording | Film or detector model: FEI FALCON IV (4k x 4k) / Average electron dose: 39.0 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: 3.0 µm / Nominal defocus min: 0.5 µm | 
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company  | 
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Image processing
| Startup model | Type of model: OTHER Details: Generated using ab-initio reconstruction routine in cryoSPARC  | 
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| Final reconstruction | Resolution.type: BY AUTHOR / Resolution: 3.57 Å / Resolution method: FSC 0.143 CUT-OFF / Number images used: 126808 | 
| Initial angle assignment | Type: RANDOM ASSIGNMENT | 
| Final angle assignment | Type: MAXIMUM LIKELIHOOD | 
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Keywords
Thermococcus kodakarensis (archaea)
Authors
United Kingdom, 2 items 
Citation
 
























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FIELD EMISSION GUN
