Scripps VIVO scripps research logo

  • Index
  • Log in
  • Home
  • People
  • Organizations
  • Research
  • Events
Search form

Characterization of large conformational changes and autoproteolysis in the maturation of a T=4 virus capsid

Academic Article
uri icon
  • Overview
  • Identity
  • Additional Document Info
  • View All
scroll to property group menus

Overview

related to degree

  • Lander, Gabriel, Ph.D. in Biophysics, Scripps Research 2004 - 2009

authors

  • Matsui, T.
  • Lander, Gabriel
  • Johnson Jr., John

publication date

  • January 2009

journal

  • Journal of Virology  Journal

abstract

  • Nudaurelia capensis omega virus-like particles have been characterized as a 480-A procapsid and a 410-A capsid, both with T=4 quasisymmetry. Procapsids transition to capsids when pH is lowered from 7.6 to 5.0. Capsids undergo autoproteolysis at residue 570, generating the 74-residue C-terminal polypeptide that remains with the particle. Here we show that the particle size becomes smaller under conditions between pH 6.8 and 6.0 without activating cleavage and that the particle remains at an intermediate size when the pH is carefully maintained. At pH 5.8, cleavage is very slow, becoming detectable only after 9 h. The optimum pH for cleavage is 5.0 (half-life, approximately 30 min), with a significant reduction in the cleavage rate at pH values below 5. We also show that lowering the pH is required only to make the virus particles compact and to presumably form the active site for autoproteolysis but not for the chemistry of cleavage. The cleavage reaction proceeds at pH 7.0 after approximately 10% of the subunits cleave at pH 5.0. Employing the virion crystal structure for reference, we investigated the role of electrostatic repulsion of acidic residues in the pH-dependent large conformational changes. Three mutations of Glu to Gln that formed procapsids showed three different phenotypes on maturation. One, close to the threefold and quasithreefold symmetry axes and far from the cleavage site, did not mature at pH 5, and electron cryomicroscopy reconstruction showed that it was intermediate in size between those of the procapsid and capsid; one near the cleavage site exhibited a wild-type phenotype; and a third, far from the cleavage site, resulted in cleavage of 50% of the subunits after 4 h, suggesting quasiequivalent specificity of the mutation.

subject areas

  • Capsid Proteins
  • Hydrogen-Ion Concentration
  • Insect Viruses
  • Models, Molecular
  • Mutation, Missense
  • Peptide Hydrolases
  • Protein Conformation
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Virion
  • Virus Assembly
scroll to property group menus

Identity

PubMed Central ID

  • PMC2612371

International Standard Serial Number (ISSN)

  • 0022-538X

Digital Object Identifier (DOI)

  • 10.1128/jvi.01859-08

PubMed ID

  • 18987141
scroll to property group menus

Additional Document Info

start page

  • 1126

end page

  • 1134

volume

  • 83

issue

  • 2

©2021 The Scripps Research Institute | Terms of Use | Powered by VIVO

  • About
  • Contact Us
  • Support