Refined Cryo-EM Structure of the T4 Tail Tube: Exploring the Lowest Dose Limit

Weili Zheng, Fengbin Wang, Nicholas M.I. Taylor, Ricardo C. Guerrero-Ferreira, Petr Leiman, Edward H. Egelman

Research output: Contribution to journalArticle

8 Scopus citations


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/Å2 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. Zheng et al. describe a 3.4 Å resolution cryo-electron microscopy reconstruction of the bacteriophage T4 tail tube, used for injecting DNA into bacterial cells. Remarkably, this was accomplished using legacy software. They show that once images are aligned, a reconstruction can be generated with a dose of 1.5 electrons/Å2.

Original languageEnglish (US)
StateAccepted/In press - 2017



  • Bacteriophage
  • Bacteriophage tail
  • Contractile injection system
  • Helical filaments
  • R-type pyocin

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

Cite this

Zheng, W., Wang, F., Taylor, N. M. I., Guerrero-Ferreira, R. C., Leiman, P., & Egelman, E. H. (Accepted/In press). Refined Cryo-EM Structure of the T4 Tail Tube: Exploring the Lowest Dose Limit. Structure.