Three-dimensional reconstructions of the bacteriophage CUS-3 virion reveal a conserved coat protein I-domain but a distinct tailspike receptor-binding domain

Virology. 2014 Sep:464-465:55-66. doi: 10.1016/j.virol.2014.06.017. Epub 2014 Jul 18.

Abstract

CUS-3 is a short-tailed, dsDNA bacteriophage that infects serotype K1 Escherichia coli. We report icosahedrally averaged and asymmetric, three-dimensional, cryo-electron microscopic reconstructions of the CUS-3 virion. Its coat protein structure adopts the "HK97-fold" shared by other tailed phages and is quite similar to that in phages P22 and Sf6 despite only weak amino acid sequence similarity. In addition, these coat proteins share a unique extra external domain ("I-domain"), suggesting that the group of P22-like phages has evolved over a very long time period without acquiring a new coat protein gene from another phage group. On the other hand, the morphology of the CUS-3 tailspike differs significantly from that of P22 or Sf6, but is similar to the tailspike of phage K1F, a member of the extremely distantly related T7 group of phages. We conclude that CUS-3 obtained its tailspike gene from a distantly related phage quite recently.

Keywords: Bacteriophage; CUS-3; Cryo-electron microscopy; Virion structure.

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 / metabolism
  • Bacteriophages / ultrastructure*
  • Capsid Proteins / chemistry*
  • Capsid Proteins / genetics
  • Capsid Proteins / metabolism*
  • Capsid Proteins / ultrastructure
  • Conserved Sequence
  • Cryoelectron Microscopy
  • Models, Molecular
  • Molecular Sequence Data
  • Phylogeny
  • Protein Binding
  • Protein Structure, Tertiary
  • Virion / chemistry
  • Virion / genetics
  • Virion / metabolism
  • Virion / ultrastructure*

Substances

  • Capsid Proteins