Polyhedra structures and the evolution of the insect viruses.
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 ⩽ 1.5 Å), whilst pairwise sequence identities, based on structural alignment, are as little as 12%. These structures illustrate the effect of 400 million 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.
Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, United Kingdom.
Xiaoyun
X
Ji
Diamond House, Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Danny
D
Axford
Diamond House, Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Robin
R
Owen
Diamond House, Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Gwyndaf
G
Evans
Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, United Kingdom.
Helen M
HM
Ginn
Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, United Kingdom.
Geoff
G
Sutton
Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, United Kingdom; Diamond House, Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom. Electronic address: dave@strubi.ox.ac.uk.
David I
DI
Stuart
D000595:Amino Acid Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D003570:Cytidine Triphosphate / Q000737:chemistry; D019143:Evolution, Molecular; D007304:Insect Viruses / Q000648:ultrastructure*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D015678:Viral Structural Proteins / Q000737:chemistry* / Q000648:ultrastructure
D015678:Viral Structural Proteins; D003570:Cytidine Triphosphate
Cypovirus; In vivo crystals; Micro focus crystallography; Polyhedra; Protein microcrystals