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Open data
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Basic information
Entry | Database: PDB / ID: 6qem | ||||||||||||
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Title | E. coli DnaBC complex bound to ssDNA | ||||||||||||
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![]() | REPLICATION / Helicase / helicase loader / AAA+ / RecA | ||||||||||||
Function / homology | ![]() DnaB-DnaC complex / DnaB-DnaC-Rep-PriC complex / DnaB-DnaG complex / DnaB-DnaC-DnaT-PriA-PriC complex / DnaB-DnaC-DnaT-PriA-PriB complex / DNA helicase complex / DNA 5'-3' helicase / primosome complex / DNA replication, synthesis of primer / replisome ...DnaB-DnaC complex / DnaB-DnaC-Rep-PriC complex / DnaB-DnaG complex / DnaB-DnaC-DnaT-PriA-PriC complex / DnaB-DnaC-DnaT-PriA-PriB complex / DNA helicase complex / DNA 5'-3' helicase / primosome complex / DNA replication, synthesis of primer / replisome / DNA duplex unwinding / DNA strand elongation involved in DNA replication / response to ionizing radiation / DNA unwinding involved in DNA replication / replication fork processing / DNA replication initiation / DNA helicase activity / helicase activity / Hydrolases; Acting on acid anhydrides; Acting on acid anhydrides to facilitate cellular and subcellular movement / 5'-3' DNA helicase activity / DNA replication / ATP hydrolysis activity / DNA binding / ATP binding / identical protein binding / cytosol Similarity search - Function | ||||||||||||
Biological species | ![]() ![]() | ||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.4 Å | ||||||||||||
![]() | Arias-Palomo, E. / Puri, N. / O'Shea Murray, V.L. / Yan, Q. / Berger, J.M. | ||||||||||||
Funding support | ![]() ![]()
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![]() | ![]() Title: Physical Basis for the Loading of a Bacterial Replicative Helicase onto DNA. Authors: Ernesto Arias-Palomo / Neha Puri / Valerie L O'Shea Murray / Qianyun Yan / James M Berger / ![]() ![]() Abstract: In cells, dedicated AAA+ ATPases deposit hexameric, ring-shaped helicases onto DNA to initiate chromosomal replication. To better understand the mechanisms by which helicase loading can occur, we ...In cells, dedicated AAA+ ATPases deposit hexameric, ring-shaped helicases onto DNA to initiate chromosomal replication. To better understand the mechanisms by which helicase loading can occur, we used cryo-EM to determine sub-4-Å-resolution structures of the E. coli DnaB⋅DnaC helicase⋅loader complex with nucleotide in pre- and post-DNA engagement states. In the absence of DNA, six DnaC protomers latch onto and crack open a DnaB hexamer using an extended N-terminal domain, stabilizing this conformation through nucleotide-dependent ATPase interactions. Upon binding DNA, DnaC hydrolyzes ATP, allowing DnaB to isomerize into a topologically closed, pre-translocation state competent to bind primase. Our data show how DnaC opens the DnaB ring and represses the helicase prior to DNA binding and how DnaC ATPase activity is reciprocally regulated by DnaB and DNA. Comparative analyses reveal how the helicase loading mechanism of DnaC parallels and diverges from homologous AAA+ systems involved in DNA replication and transposition. | ||||||||||||
History |
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Structure visualization
Movie |
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Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 1.3 MB | Display | ![]() |
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PDB format | ![]() | 1.1 MB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 4538MC ![]() 4537C ![]() 6qelC C: citing same article ( M: map data used to model this data |
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Similar structure data |
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Links
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Assembly
Deposited unit | ![]()
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1 |
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Components
-Protein , 2 types, 12 molecules ABCDEFGHIJKL
#1: Protein | Mass: 52450.945 Da / Num. of mol.: 6 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() ![]() #2: Protein | Mass: 27973.152 Da / Num. of mol.: 6 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() ![]() |
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-DNA chain , 1 types, 1 molecules M
#3: DNA chain | Mass: 10905.983 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) ![]() ![]() |
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-Non-polymers , 3 types, 16 molecules ![](data/chem/img/08T.gif)
![](data/chem/img/MG.gif)
![](data/chem/img/ADP.gif)
![](data/chem/img/MG.gif)
![](data/chem/img/ADP.gif)
#4: Chemical | ChemComp-08T / [[[( #5: Chemical | ChemComp-MG / #6: Chemical | ChemComp-ADP / |
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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
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Molecular weight | Value: 0.49 MDa / Experimental value: NO | ||||||||||||||||||||||||
Source (natural) |
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Source (recombinant) |
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Buffer solution | pH: 7.5 | ||||||||||||||||||||||||
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES | ||||||||||||||||||||||||
Specimen support | Details: The grids were pre-treated with poly-lys / Grid material: COPPER / Grid mesh size: 400 divisions/in. / Grid type: C-flat-1.2/1.3 | ||||||||||||||||||||||||
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 90 % |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 2700 nm / Nominal defocus min: 1200 nm / Cs: 2.7 mm |
Image recording | Electron dose: 58 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
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Processing
Software |
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EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||||||||||||||
Particle selection | Num. of particles selected: 473888 | ||||||||||||||||||||||||||||||||||||
Symmetry | Point symmetry: C1 (asymmetric) | ||||||||||||||||||||||||||||||||||||
3D reconstruction | Resolution: 3.4 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 229097 / Symmetry type: POINT | ||||||||||||||||||||||||||||||||||||
Atomic model building | Protocol: OTHER / Space: REAL | ||||||||||||||||||||||||||||||||||||
Refinement | Stereochemistry target values: GeoStd + Monomer Library | ||||||||||||||||||||||||||||||||||||
Refine LS restraints |
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