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PDBsum entry 5a9c
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Viral protein
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PDB id
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5a9c
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References listed in PDB file
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Key reference
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Title
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Polyhedra structures and the evolution of the insect viruses.
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Authors
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X.Ji,
D.Axford,
R.Owen,
G.Evans,
H.M.Ginn,
G.Sutton,
D.I.Stuart.
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Ref.
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J Struct Biol, 2015,
192,
88-99.
[DOI no: ]
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PubMed id
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Abstract
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Polyhedra represent an ancient system used by a number of insect viruses to
protect virions during long periods of environmental exposure. We present high
resolution crystal structures of polyhedra for seven previously uncharacterised
types of cypoviruses, four using ab initio selenomethionine phasing (two of
these required over 100 selenomethionine crystals each). Approximately 80% of
residues are structurally equivalent between all polyhedrins (pairwise rmsd
⩽1.5Å), whilst pairwise sequence identities, based on structural alignment,
are as little as 12%. These structures illustrate the effect of 400million years
of evolution on a system where the crystal lattice is the functionally conserved
feature in the face of massive sequence variability. The conservation of crystal
contacts is maintained across most of the molecular surface, except for a
dispensable virus recognition domain. By spreading the contacts over so much of
the protein surface the lattice remains robust in the face of many individual
changes. Overall these unusual structural constraints seem to have skewed the
molecule's evolution so that surface residues are almost as conserved as the
internal residues.
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