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Title:The bacterial DnaC helicase loader is a DnaB ring breaker
Authors:Arias-Palomo E, O'Shea VL, Hood IV, Berger JM
Sample:E. coli DnaB replicative helicase
Method:Single particle reconstruction (25 angstroms resolution)
Red flagLatest update:2013-04-24
Sample name: E. coli DnaB replicative helicase
Oligomeric state: Homohexamer
Theoretical molecular weight of the sample: 0.312
ID Type Name Exp. MW (MDa) Theo. MW (MDa) Oligomeric details Recombinant expression Synthetic Organism UniProt identifier GO identifier InterPro identifier Virus identifier Details
1proteinDnaB replicative helicase0.052hexamertrueEscherichia coliP0ACB0
Specimen state: Particle
Specimen preparation:
pHSpecimen conc.DetailsStainingSpecimen support details
8.5 mg/mL20 mM Tris-HCl pH 8.5, 200 mM NaCl, 5 % glycerol, 5 mM MgCl2, 1 mM beta-mercaptoethanol, and 1 mM ADP-BeF3Grids with adsorbed protein were floated on 2% w/v uranyl formate for 45 seconds400 mesh copper grid with thin carbon support, glow discharged for 20 seconds
Cryogen nameHumidityTemp.Instr.MethodTime resolvedDetails
MicroscopeVoltageIllumination modeImaging modeCsDefocus min.Defocus max.Nominal mag.Calibrated mag.Electron sourceDetectorDetector distanceAstigmatism
FEI TECNAI 12120 kVFLOOD BEAMBRIGHT FIELD6.3 mm700 nm1200 nm49000LAB6GENERIC TVIPS (4k x 4k) mm

Specimen holderHolder modelTilt min.Tilt max.Energy filterEnergy windowTemp.Temp. min.Temp. max.Beam tiltElectron doseOther detailsDate
SIDE ENTRY, EUCENTRIC°° eV297 K K K mrad25 e/Å221-JAN-2011
Protocol:Projection matching
Software:EMAN2, SPARX
CTF correction:Each micrograph
Number of particles:9617
Imposed symmetry:C3
Resolution by author:25 Å
Resolution method:FSC 0.5
Processing details:The particles were selected using DoG picker as available in APPION. The contrast transfer function of the microscope for each micrograph was estimated using CTFFIND3 and phase-flipped using SPIDER. DnaBC particles were subjected to a multi-model refinement as implemented in SPARX using the 3D averages obtained from the RCT reconstructions as initial references.
PDBProtocolTarget crit.SoftwareB valueFitting spacePDB chainDetails