Toroidal surface complexes of bacteriophage ϕ12 are responsible for host-cell attachment

Virology. 2011 Jun 5;414(2):103-9. doi: 10.1016/j.virol.2011.03.020. Epub 2011 Apr 13.


Cryo-electron tomography and subtomogram averaging are utilized to determine that the bacteriophage ϕ12, a member of the Cystoviridae family, contains surface complexes that are toroidal in shape, are composed of six globular domains with six-fold symmetry, and have a discrete density connecting them to the virus membrane-envelope surface. The lack of this kind of spike in a reassortant of ϕ12 demonstrates that the gene for the hexameric spike is located in ϕ12's medium length genome segment, likely to the P3 open reading frames which are the proteins involved in viral-host cell attachment. Based on this and on protein mass estimates derived from the obtained averaged structure, it is suggested that each of the globular domains is most likely composed of a total of four copies of P3a and/or P3c proteins. Our findings may have implications in the study of the evolution of the cystovirus species in regard to their host specificity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteriophages / chemistry
  • Bacteriophages / genetics
  • Bacteriophages / physiology*
  • Host Specificity*
  • Molecular Sequence Data
  • Open Reading Frames
  • Protein Structure, Tertiary
  • Pseudomonas syringae / virology*
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism*
  • Virus Attachment*


  • Viral Envelope Proteins