DNA packaging and delivery machines in tailed bacteriophages

Curr Opin Struct Biol. 2007 Apr;17(2):237-43. doi: 10.1016/j.sbi.2007.03.011. Epub 2007 Mar 28.


Several symmetric and asymmetric reconstructions of bacteriophage particles have recently been determined using electron cryo-microscopy and image reconstruction, and X-ray crystal structures of phage particles and particle-associated gene products have also been solved. In the past two years, the asymmetric structures of four different phages, T7, epsilon15, P22 and phi29, were determined at resolutions sufficient to visualize details of the machinery for DNA packaging and delivery, as well as the organization of the double-stranded DNA within the particles. Invariably, the portals, through which DNA enters and leaves the particle, have 12-fold symmetry, occupy a pentavalent site in the capsid and, along with tail machine accessory proteins attached to it, are fixed in a specific orientation relative to the rest of the capsid.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Bacillus Phages / chemistry
  • Bacillus Phages / physiology
  • Bacillus Phages / ultrastructure
  • Bacteriophage P22 / chemistry
  • Bacteriophage P22 / physiology
  • Bacteriophage P22 / ultrastructure
  • Bacteriophage T4 / chemistry
  • Bacteriophage T4 / physiology
  • Bacteriophage T4 / ultrastructure
  • Bacteriophage T7 / chemistry
  • Bacteriophage T7 / physiology
  • Bacteriophage T7 / ultrastructure
  • Bacteriophages / chemistry*
  • Bacteriophages / physiology*
  • Bacteriophages / ultrastructure
  • Cryoelectron Microscopy
  • Crystallography, X-Ray
  • DNA Packaging / physiology*
  • DNA, Viral / chemistry
  • Imaging, Three-Dimensional
  • Models, Molecular
  • Virus Assembly


  • DNA, Viral