Polyhedra structures and the evolution of the insect viruses

DOI: 10.1016/j.jsb.2015.08.009
PMID: 26291392

Authors: Xiaoyun Ji (The Wellcome Trust Centre for Human Genetics) , Danny Axford (Diamond Light Source) , Robin Owen (Diamond Light Source) , Gwyndaf Evans (Diamond Light Source) , Helen Ginn (University of Oxford) , Geoff Sutton (University of Oxford) , Dave Stuart (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Structural Biology

State: Published (Approved)
Published: August 2015
Diamond Proposal Number(s): 6387

Abstract: 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 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.

Journal Keywords: Protein Microcrystals; Polyhedra; In Vivo Crystals; Cypovirus; Micro Focus Crystallography

Subject Areas: Biology and Bio-materials


Instruments: I24-Microfocus Macromolecular Crystallography

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