Refined Cryo-EM Structure of the T4 Tail Tube: Exploring the Lowest Dose Limit.
Zheng, W., Wang, F., Taylor, N.M.I., Guerrero-Ferreira, R.C., Leiman, P.G., Egelman, E.H.(2017) Structure 25: 1436-1441.e2
- PubMed: 28757144 
- DOI: https://doi.org/10.1016/j.str.2017.06.017
- Primary Citation of Related Structures:  
5W5E, 5W5F - PubMed Abstract: 
The bacteriophage T4 contractile tail (containing a tube and sheath) was the first biological assembly reconstructed in three dimensions by electron microscopy at a resolution of ∼35 Å in 1968. A single-particle reconstruction of the T4 baseplate was able to generate a 4.1 Å resolution map for the first two rings of the tube using the overall baseplate for alignment. We have now reconstructed the T4 tail tube at a resolution of 3.4 Å, more than a 1,000-fold increase in information content for the tube from 1968. We have used legacy software (Spider) to show that we can do better than the typical 2/3 Nyquist frequency. A reasonable map can be generated with only 1.5 electrons/Å 2 using the higher dose images for alignment, but increasing the dose results in a better map, consistent with other reports that electron dose does not represent the main limitation on resolution in cryo-electron microscopy.
Organizational Affiliation: 
Department of Biochemistry and Molecular Genetics, University of Virginia Medical School, Charlottesville, VA 22908, USA.