Cryo-EM based theoretical model structure of transmembrane domain of the multidrug-resistance antiporter from E. coli EmrE
ELECTRON CRYSTALLOGRAPHY
Crystal Data
Unit Cell
Length ( Å )
Angle ( ˚ )
a = 1
α = 90
b = 1
β = 90
c = 1
γ = 90
Symmetry
Space Group
P 1
Diffraction
Diffraction Experiment
ID #
Crystal ID
Scattering Type
Data Collection Temperature
Detector
Detector Type
Details
Collection Date
Monochromator
Protocol
1
1
electron
M
SINGLE WAVELENGTH
Refinement
Non-Hydrogen Atoms Used in Refinement
Non-Hydrogen Atoms
Number
Protein Atoms
624
Nucleic Acid Atoms
Solvent Atoms
Heterogen Atoms
Sample
multidrug-resistance antiporter from E. coli EmrE
Specimen Preparation
Sample Aggregation State
2D ARRAY
Vitrification Instrument
HOMEMADE PLUNGER
Cryogen Name
NITROGEN
Sample Vitrification Details
3D Reconstruction
Reconstruction Method
CRYSTALLOGRAPHY
Number of Particles
Reported Resolution (Å)
7.5
Resolution Method
OTHER
Other Details
Canonical alpha-helices were fitted into a cryo-EM structure of EmrE at 6Angstroms in-plane and 16Angstroms vertical resolution. The sequence segments ...
Canonical alpha-helices were fitted into a cryo-EM structure of EmrE at 6Angstroms in-plane and 16Angstroms vertical resolution. The sequence segments were assigned based on biophysical and sequence data as elaborated in the principal citation. The orientation of each helix around its principal axis was set using evolutionary conservation, requiring that evolutionarily conserved positions be packed inside the core of the protein, whereas variable residues face the outside. A kink was introduced in helix C to fit a bend in the cryo-EM structure and according to sequence clues (see principal citation).
A full description of potential inaccuracies in the model is presented in the principal citation. In brief, these include the following: the vertical positioning of the helices may be wrong by several Angstroms due to the low vertical resolution of the cryo-EM structure; the orientations of the helices around their principal axes may vary by about 20 degrees; the positions of backbone atoms on the terminal turns of each helix may not conform to alpha-helical ideality as assumed in the model structure.
