ELECTRON MICROSCOPY

Sample

Bacteriophage T7 MLD capsid II

Specimen Preperation
Sample Aggregation State PARTICLE
Vitrification Instrument FEI VITROBOT MARK I
Cryogen Name ETHANE
Sample Vitrification Details Blot for 2 seconds twice with 2 mm offset before plunging into liquid ethane (FEI VITROBOT MARK I).
3D Reconstruction
Reconstruction Method SINGLE PARTICLE
Number of Particles 43417
Reported Resolution (Å) 3.5
Resolution Method FSC 0.143 CUT-OFF
Other Details Particles were selected from scanned micrograph images, first automatically by the ethan method and then by manual screening with the boxer program in EMAN. The TEM instrument contrast transfer function parameters were determined automatically using fitctf2.py and were then visually validated using the EMAN ctfit program. The datasets were then divided into two subsets (even and odd) and processed completely independently, including both initial models and refinements. For 3D reconstructions, the whole datasets were divided into even-odd halves and the initial de novo models and subsequent iterative refinements were all independently performed for each half dataset. The images were first binned 4x to obtain initial models and particle parameters assuming icosahedral symmetry. De novo initial models were built using the random model approach. Random subsets of particles were assigned random initial orientations and iteratively refined until convergence. Consistent icosahedral capsid structures (other than occasional differences in handedness) were obtained by repeating the random model process. Particles with inconsistent/unstable view parameters in the initial refinements were excluded in further image processing. The orientation and center parameters were then transferred to the un-binned images for high-resolution refinements which included Simplex method-based orientation/center optimization and grid search-based refinement of defocus, astigmatism, and magnification of the images. All image refinement and reconstructions were performed with in-house developed programs jspr.py (for overall work-flow), jalign (for 2D alignment) and j3dr (for 3D reconstruction), which use EMAN and EMAN2 library functions.
Refinement Type
Symmetry Type POINT
Map-Model Fitting and Refinement
ID 1
Refinement Space ?
Refinement Protocol ?
Refinement Target ?
Overall B Value ?
Fitting Procedure ?
Details ?
Data Acquisition
Detector Type KODAK SO-163 FILM
Electron Dose (electrons/Å2) 25
Imaging Experiment
Date of Experiment 2011-01-07
Temprature (Kelvin)
Microscope Model FEI TITAN KRIOS
Minimum Defocus (nm) 500
Maximum Defocus (nm) 3300
Minimum Tilt Angle (degrees) ?
Maximum Tilt Angle (degrees) ?
Nominal CS 2.7
Imaging Mode BRIGHT FIELD
Specimen Holder Model FEI TITAN KRIOS AUTOGRID HOLDER
Nominal Magnification 59000
Calibrated Magnification 57727
Source FIELD EMISSION GUN
Acceleration Voltage (kV) 300
Imaging Details ?
Imaging Experiment
Task Software Package Version
RECONSTRUCTION EMAN 1
RECONSTRUCTION EMAN 2
RECONSTRUCTION jspr ?
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details
. Each particle