Subunit Conformational Changes Accompanying Bacteriophage P22 Capsid Maturation

Academic Article

Abstract

  • In double-stranded DNA bacteriophages, packaging of dsDNA requires the transformation of a precursor procapsid into a mature viral capsid. Lattice expansion and release of scaffolding subunits accompany DNA packaging. Three-dimensional structures of procapsid and mature phage lattices demonstrate that the capsid transformation involves substantial changes in subunit environment. Since this transformation occurs without subunit dissociation, it represents a transition between at least two stable subunit conformations. Using Raman spectroscopy, we have identified changes in coat protein secondary structure and side-chain environments which accompany the capsid transformation. The subunits of procapsid shells contain only 2.0 ± 0.4% more α-helix and less β-sheet than those of mature capsids; however, numerous side chains are substantially altered by the transformation, including tyrosines, tryptophans, phenylalanines, and aliphatics, which are widely distributed through the subunit sequence. We propose, therefore, that procapsid expansion is accomplished through the relative motion of coat subunit domains with little change in secondary structure. Such hinge-bending conformational transitions may couple ATP-dependent dsDNA condensation with shell expansion. © 1993, American Chemical Society. All rights reserved.
  • Published In

  • Biochemistry  Journal
  • Digital Object Identifier (doi)

    Author List

  • Prevelige PE; Thomas D; Aubrey KL; Towse SA; Thomas GJ
  • Start Page

  • 537
  • End Page

  • 543
  • Volume

  • 32
  • Issue

  • 2