1ql2
INOVIRUS (FILAMENTOUS BACTERIOPHAGE) STRAIN PF1 MAJOR COAT PROTEIN ASSEMBLY
|
OverviewOverview
The major coat protein in the capsid of Pf1 filamentous bacteriophage, (Inovirus) forms a helical assembly of about 7000 identical protein, subunits, each of which contains 46 amino-acid residues and can be closely, approximated by a single gently curved alpha-helix. Since the viral DNA, occupies the core of the tubular capsid and appears to make no significant, specific interactions with the capsid proteins, the capsid is a simple, model system for the study of the static and dynamic properties of, alpha-helix assembly. The capsid undergoes a reversible, temperature-induced structural transition at about 283 K between two, slightly different helix forms. The two forms can coexist without an, intermediate state, consistent with a first-order structural phase, transition. The molecular model of the higher temperature form was refined, using improved X-ray fibre diffraction data and new refinement and, validation methods. The refinement indicates that the two forms are, related by a change in the orientation of the capsid subunits within the, virion, without a significant change in local conformation of the, subunits. On the higher temperature diffraction pattern there is a region, of observed intensity that is not consistent with a simple helix of, identical subunits; it is proposed that the structure involves groups of, three subunits which each have a slightly different orientation within the, group. The grouping of subunits suggests that a change in subunit, libration frequency could be the basis of the Pf1 structural transition;, calculations from the model are used to explore this idea.
About this StructureAbout this Structure
1QL2 is a Single protein structure of sequence from Pseudomonas phage pf1. Full crystallographic information is available from OCA.
ReferenceReference
The molecular structure and structural transition of the alpha-helical capsid in filamentous bacteriophage Pf1., Welsh LC, Symmons MF, Marvin DA, Acta Crystallogr D Biol Crystallogr. 2000 Feb;56(Pt 2):137-50. PMID:10666593
Page seeded by OCA on Wed Nov 21 00:47:14 2007