EMD-2321 Experiments and Validation

The bacterial DnaC helicase loader is a DnaB ring breaker

Single particle reconstruction
Overview of EMD-2321
Sample name: E. coli DnaB helicase bound to the DnaC loading factor
Organism: Escherichia coli
Related EM entry by publication: EMD-2322

Map parameters

Recommended contour level: 3.00 (author)
Number of grid points: 80 × 80 × 80
Voxel size: 4.36 × 4.36 × 4.36 Å
Minimum density: -5.65
Maximum density: 13.013
Average density: 0.00
Standard deviation: 1.00

Sample information

Sample name: E. coli DnaB helicase bound to the DnaC loading factor
Proteins: DnaB replicative helicase, DnaC helicase loading factor

Validation information

Experimental information


Image processing

Applied symmetry: C1
Software: EMAN2, SPARX
Number of particles: 17942
Reconstruction protocol: Projection matching
CTF correction: Each micrograph


Microscope model: FEI TECNAI 12
Electron source: LAB6
Electron dose (e/A**2): 25.0
Nominal CS (mm): 6.30
Nominal magnification: 49000.0
Defocus max (nm): 1,200.00
Defocus min (nm): 700.00


Specimen state: particle
Buffer: 20 mM Tris-HCl pH 8.5, 200 mM NaCl, 5 % glycerol, 5 mM MgCl2, 1 mM beta-mercaptoethanol, and 1 mM ADP-BeF3
Staining procedure: Grids with adsorbed protein were floated on 2% w/v uranyl formate for 45 seconds
Specimen support: 400 mesh copper grid with thin carbon support, glow discharged for 20 seconds
Apparatus: NONE
Cryogen: NONE