ELECTRON MICROSCOPY

Sample

SPIROPLASMA VIRUS

Specimen Preperation
Sample Aggregation State PARTICLE
Vitrification Instrument ?
Cryogen Name ETHANE
Sample Vitrification Details ?
3D Reconstruction
Reconstruction Method SINGLE PARTICLE
Number of Particles ?
Reported Resolution (Å) 27
Resolution Method OTHER
Other Details CA TRACING OF A MODEL OF THE CAPSID PROTEIN VP1 OF SPV4 BASED ON THE CRYSTAL STRUCTURAL COORDINATES OF THE MAJOR CAPSID PROTEIN F OF PHIX174 (RESIDUES 1001 - 1427). A 71 AMINO ACID PORTION OF VP1 WAS MODELLED (GLY 226 - THR 297) AS AN INSERTION LOOP BETWEEN RESIDUES THR 1187 AND THR 1188 OF THE F CAPSID PROTEIN OF PHIX174. THE COORDINATES ARE IN THE P, Q, R FRAME IN ANGSTROM UNITS AND CORRESPOND TO ICOSAHEDRAL SYMMETRY AXES. THE ORIGIN IS CHOSEN AT THE CENTER OF THE VIRUS WITH P, Q AND R ALONG MUTUALLY PERPENDICULAR TWO-FOLD AXES OF THE ICOSAHEDRON. RESIDUES 1001 - 1187 AND 1187 - 1426 ARE THE CA COORDINATES OF THE F CAPSID PROTEIN OF PHIX174. INSERTED BETWEEN RESIDUES 1187 AND 1188 IS A MODELLED CA TRACING OF A 71 AMINO ACID INSERTION LOOP OF SPV4 (RESIDUES 226 - 297) OF THE VP1 CAPSID PROTEIN, BASED ON THE CRYO-EM RECONSTRUCTION ENVELOPE AND STRUCTURAL ALIGNMENT AND SECONDARY STRUCTURE PREDICTION. THE RESOLUTION OF THE FINAL RECONSTRUCTED DENSITY MAP WAS DETERMINED TO BE AT LEAST 27 ANGSTROMS AS MEASURED BY STRUCTURE FACTOR COMPARISONS (BAKER ET AL. 1991, BIOPHYS. J. 60,1445-1456) AND FOURIER RING CORRELATION MEASUREMENTS (CONWAY ET AL. 1996, J. STRUC. BIOL. 116, 200-208)
Refinement Type
Symmetry Type POINT
Map-Model Fitting and Refinement
ID 1
Refinement Space RECIPROCAL
Refinement Protocol ?
Refinement Target ?
Overall B Value ?
Fitting Procedure ?
Details DETAILS--THE CRYSTAL STRUCTURE OF HRV16 WAS PLACED INTO THE CALIBRATED CRYO-EM DENSITY MAP BY ALIGNING THE ICOSAHEDRAL SYMMETRY AXES. APPROPRIATELY GLYCOSYLATED MODELS OF D1D2-ICAM-1 WITH VARIOUS INTERDOMAIN ANGLES (AS SEEN IN DIFFERENT CRYSTAL STRUCTURES OF D1D2-ICAM-1), WERE FIRST MANUALLY FITTED INTO THE CRYO-EM DENSITY CORRESPONDING TO THE ICAM-1 FRAGMENT, AND SUBSEQUENTLY REFINED AS RIGID BODIES IN RECIPROCAL SPACE. OBSERVED STRUCTURE FACTORS WERE OBTAINED BY INVERSE FOURIER TRANSFORM OF CRYO-EM DIFFERENCE MAPS CALCULATED BY- 1) SUBSTRACTION OF THE HRV16 AND RNA CONTRIBUTION FROM THE CRYO-EM RECONSTRUCTED DENSITY OF THE COMPLEXES; 2) REDUCTION OF THE DIFFERENCE MAPS TO AN ICOSAHEDRAL ASYMMETRIC UNIT. THE COORDINATES ARE IN THE P, Q, R FRAME IN ANGSTROM UNITS AND CORRESPOND TO ICOSAHEDRAL SYMMETRY AXES. THE ORIGIN IS CHOSEN AT THE CENTER OF THE VIRUS WITH P, Q AND R ALONG MUTUALLY PERPENDICULAR TWO-FOLD AXES OF THE ICOSAHEDRON. THEY SHOULD REMAIN IN THAT FRAME FOR THE EASE OF THE USER IN CREATING THE BIOLOGICALLY SIGNIFICANT VIRAL COMPLEX PARTICLE USING THE 60 ICOSAHEDRAL SYMMETRY OPERATORS. RESIDUES NOT VISIBLE IN THE ORIGINAL CRYSTAL STRUCTURES ARE NOT INCLUDED IN THE CRYO-EM STRUCTURE MODEL. FOR EXAMPLE, HRV16 RESIDUES 2001-2009, 4008-4022 AND 4045-4068 ARE NOT VISIBLE IN THE CRYSTAL STRUCTURE (PDB ENTRY 1AYM) AND THEREFORE ARE NOT INCLUDED IN THE COORDINATES BELOW.
Data Acquisition
Detector Type KODAK SO-163 FILM
Electron Dose (electrons/Å2) 18.
Imaging Experiment
Date of Experiment ?
Temprature (Kelvin)
Microscope Model FEI/PHILIPS EM420
Minimum Defocus (nm) ?
Maximum Defocus (nm) 800.
Minimum Tilt Angle (degrees) ?
Maximum Tilt Angle (degrees) ?
Nominal CS ?
Imaging Mode BRIGHT FIELD
Specimen Holder Model .
Nominal Magnification 49000
Calibrated Magnification ?
Source ?
Acceleration Voltage (kV) .
Imaging Details ?
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details