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The Crystallographic Structure of Panicum Mosaic Virus
Structural highlights
FunctionCAPSD_PMVK Capsid protein self-assembles to form an icosahedral capsid with a T=3 symmetry, about 32-35 nm in diameter, and consisting of 180 capsid proteins. Publication Abstract from PubMedThe structure of Panicum Mosaic Virus (PMV) was determined by X-ray diffraction analysis to 2.9A resolution. The crystals were of pseudo symmetry F23; the true crystallographic unit cell was of space group P2(1) with a=411.7A, b=403.9A and c=412.5A, with beta=89.7 degrees . The asymmetric unit was two entire T=3 virus particles, or 360 protein subunits. The structure was solved by conventional molecular replacement from two distant homologues, Cocksfoot Mottle Virus (CfMV) and Tobacco Necrosis Virus (TNV), of approximately 20% sequence identity followed by phase extension. The model was initially refined with exact icosahedral constraints and then with icosahedral restraints. The virus has Ca(++) ions octahedrally coordinated by six aspartic acid residues on quasi threefold axes, which is completely different than for either CfMV or TNV. Amino terminal residues 1-53, 1-49 and 1-21 of the A, B and C subunits, respectively, and the four C-terminal residues (239-242) are not visible in electron density maps. The additional ordered residues of the C chain form a prominent "arm" that intertwines with symmetry equivalent "arms" at icosahedral threefold axes, as was seen in both CfMV and TNV. A 17 nucleotide hairpin segment of genomic RNA is icosahedrally ordered and bound at 60 equivalent sites at quasi twofold A-B subunit interfaces at the interior surface of the capsid. This segment of RNA may serve as a conformational switch for coat protein subunits, as has been proposed for similar RNA segments in other viruses. The crystallographic structure of Panicum Mosaic Virus (PMV).,Makino DL, Larson SB, McPherson A J Struct Biol. 2012 Nov 1. pii: S1047-8477(12)00294-8. doi:, 10.1016/j.jsb.2012.10.012. PMID:23123270[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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