Functional domains of the bacteriophage P2 scaffolding protein: Identification of residues involved in assembly and protease activity

Academic Article


  • Bacteriophage P2 encodes a scaffolding protein, gpO, which is required for correct assembly of P2 procapsids from the gpN major capsid protein. The 284 residue gpO protein also acts as a protease, cleaving itself into an N-terminal fragment, O*, that remains in the capsid following maturation. In addition, gpO is presumed to act as the maturation protease for gpN, which is N-terminally processed to N*, accompanied by DNA packaging and capsid expansion. The protease activity of gpO resides in the N-terminal half of the protein. We show that gpO is a classical serine protease, with a catalytic triad comprised of Asp 19, His 48 and Ser 107. The C-terminal 90 amino acids of gpO are required and sufficient for capsid assembly. This fragment contains a predicted α-helical segment between residues 197 and 257 and exists as a multimer in solution, suggesting that oligomerization is required for scaffolding activity. Correct assembly requires the C-terminal cysteine residue, which is most likely involved in transient gpN interactions. Our results suggest a model for gpO scaffolding action in which the N-terminal half of gpO binds strongly to gpN, while oligomerization of the C-terminal α-helical domain of gpO and transient interactions between Cys 284 and gpN lead to capsid assembly. © 2008 Elsevier Inc. All rights reserved.
  • Authors

    Published In

  • Virology  Journal
  • Digital Object Identifier (doi)

    Author List

  • Chang JR; Spilman MS; Rodenburg CM; Dokland T
  • Start Page

  • 144
  • End Page

  • 150
  • Volume

  • 384
  • Issue

  • 1