1QL2

Inovirus (Filamentous Bacteriophage) Strain PF1 Major Coat Protein Assembly

Summary for 1QL2

• Entry DOI: 10.2210/pdb1ql2/pdb
• Related: 1PFI 1QL1 2IFM 2IFN 3IFM 4IFM
• Descriptor: PF1 BACTERIOPHAGE COAT PROTEIN B (1 entity in total)
• Functional Keywords: virus, virus coat protein, helical virus coat protein, ssdna viruses, inovirus, helical virus
• Biological source: PSEUDOMONAS PHAGE PF1
• Cellular location: Virion (Potential): P03621
• Total number of polymer chains: 3
• Total formula weight: 13837.18

Authors

Welsh, L.C.,Symmons, M.F.,Marvin, D.A. (deposition date: 1999-08-20, release date: 2000-02-07, Last modification date: 2024-02-14)

Primary citation

Welsh, L.C.,Symmons, M.F.,Marvin, D.A.
The Molecular Structure and Structural Transition of the Alpha-Helical Capsid in Filamentous Bacteriophage Pf1
Acta Crystallogr.,Sect.D, 56:137-, 2000

PubMed Abstract: 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.

PubMed: 10666593
DOI: 10.1107/S0907444999015334

Experimental method

FIBER DIFFRACTION (3.1 Å)