The structure of P4 procapsids produced by coexpression of capsid and external scaffolding proteins.

Academic Article


  • The double-stranded DNA bacteriophage P4 has a T = 4 icosahedral arrangement of the gpN capsid protein derived from the P2 helper phage. The precursor procapsids in addition contain an external scaffold made up of the P4-encoded Sid protein. High yields of pure P4 procapsids have been obtained by coexpressing the gpN and Sid proteins from a chimeric plasmid. Biochemical measurements show that the ratio of gpN to Sid in the procapsids is 2:1, corresponding to 120 copies of Sid per procapsid particle. A reconstruction of the P4 procapsid, made from 213 particle images to an effective resolution of about 21 A, greatly improves on the previously determined P4 procapsid structures. The structure shows a T = 4 capsid shell and a unique tandem arrangement of 120 copies of chilli-shaped Sid monomers, which form trimers and dimers on the procapsid surface.
  • Authors

    Published In

  • Virology  Journal
  • Keywords

  • Bacteriophages, Capsid, Cryoelectron Microscopy, Models, Molecular, Plasmids, Viral Structural Proteins, Virus Assembly
  • Author List

  • Dokland T; Wang S; Lindqvist BH
  • Start Page

  • 224
  • End Page

  • 231
  • Volume

  • 298
  • Issue

  • 2