ELECTRON MICROSCOPY

Sample

Tau filaments extracted from the Frontal cortex of a patient with corticobasal degeneration.

Specimen Preperation
Sample Aggregation State FILAMENT
Vitrification Instrument FEI VITROBOT MARK IV
Cryogen Name ETHANE
Sample Vitrification Details Blot force: -12 ; Blot time: 4s
3D Reconstruction
Reconstruction Method HELICAL
Number of Particles 24073
Reported Resolution (Å) 3.2
Resolution Method FSC 0.143 CUT-OFF
Other Details ?
Refinement Type
Symmetry Type HELICAL
Map-Model Fitting and Refinement
ID 1
Refinement Space RECIPROCAL
Refinement Protocol AB INITIO MODEL
Refinement Target Fourier shell correlation
Overall B Value 26.63
Fitting Procedure ?
Details A stack of three consecutive monomers was refined to preserve nearest-neighbour interactions for the middle chain. Because most residues adopted cross strand conformation, hydrogen-bond restraints were imposed to preserve a parallel, in-register hydrogen bonding pattern in earlier stages of Fourier-space refinements. Local symmetry restraints were imposed to keep all beta strand rungs identical. Side-chain clashes were detected using MOLPROBITY, and corrected by iterative cycles of real-space refinement in COOT and Fourier-space refinement in REFMAC and PHENIX. For each refined structure, separate model refinements were performed against a single half-map, and the resulting model was compared to the other half-map to confirm the absence of overfitting.
Data Acquisition
Detector Type GATAN K2 SUMMIT (4k x 4k)
Electron Dose (electrons/Å2) 1.346
Imaging Experiment
Date of Experiment ?
Temprature (Kelvin)
Microscope Model FEI TITAN KRIOS
Minimum Defocus (nm) 1700
Maximum Defocus (nm) 2800
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 ?
Calibrated Magnification ?
Source FIELD EMISSION GUN
Acceleration Voltage (kV) 300
Imaging Details ?
Imaging Experiment
Task Software Package Version
PARTICLE SELECTION RELION 3.0
IMAGE ACQUISITION EPU 1.10.0.77REL
CTF CORRECTION CTFFIND 4.1
MODEL FITTING Coot 0.8.9.1
INITIAL EULER ASSIGNMENT RELION 3.0
FINAL EULER ASSIGNMENT RELION 3.0
CLASSIFICATION RELION 3.0
RECONSTRUCTION RELION 3.0
MODEL REFINEMENT REFMAC 5.8.0256
MODEL REFINEMENT PHENIX dev-2919
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details
PHASE FLIPPING AND AMPLITUDE CORRECTION Aligned, non-dose-weighted micrographs were used to estimate the contrast transfer function (CTF) using CTFFIND4.1