6QJH

Cryo-EM structure of heparin-induced 2N4R tau snake filaments

ELECTRON MICROSCOPY

Sample
heparin-induced 2N4R tau snake filaments

Specimen Preparation
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	SINGLE PARTICLE
Number of Particles	52441
Reported Resolution (Å)	3.3
Resolution Method	FSC 0.143 CUT-OFF
Other Details
Refinement Type
Symmetry Type	HELICAL
Axial Symmetry	C1
Axial Rise	4.7
Angular Rotation	-1.26

Map-Model Fitting and Refinement
Id	1
Refinement Space	RECIPROCAL
Refinement Protocol	AB INITIO MODEL
Refinement Target	Fourier shell correlation
Overall B Value	41.26
Fitting Procedure
Details	A stack of three consecutive monomers was refined to preserve nearest-neighbour interactions for the middle chain. Side-chain clashes were detected us ...	A stack of three consecutive monomers was refined to preserve nearest-neighbour interactions for the middle chain. 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	FEI FALCON III (4k x 4k)
Electron Dose (electrons/Å**2)	48

Imaging Experiment	1
Date of Experiment
Temperature (Kelvin)
Microscope Model	FEI POLARA 300
Minimum Defocus (nm)	1700
Maximum Defocus (nm)	2800
Minimum Tilt Angle (degrees)
Maximum Tilt Angle (degrees)
Nominal CS	2
Imaging Mode	BRIGHT FIELD
Specimen Holder Model	GATAN LIQUID NITROGEN
Nominal Magnification
Calibrated Magnification
Source	FIELD EMISSION GUN
Acceleration Voltage (kV)	300
Imaging Details

EM Software
Task	Software Package	Version
PARTICLE SELECTION	RELION	3.0
IMAGE ACQUISITION	EPU	1.5.0.1243REL
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	5.8.0236
MODEL REFINEMENT	PHENIX	dev-2919-000

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	303754	Manually picked

RCSB PDB Core Operations are funded by the National Science Foundation (DBI-1832184), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM133198.