1. The Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, Rex Richards Building, South Parks Road, Oxford OX1 3QU, UK
2. Present addresses: EMBL Grenoble Outstation, c/o ILL, BP156, 38042 Grenoble, Cedex 9, France (J.M.G.) C.N.R.S.-I.P.B.S., Groupe de cristallographie biologique, 205 route de Narbonne, 31077 Toulouse Cedex, France (P.G.).
3. Institute of Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Woking GU24 0NF, UK
4. C.N.E.V.A. Alfort, Laboratoire Central de Recherches Vétérinaires, 22 rue Pierre Curie, BP67, 94703 Maisons Alfort Cedex, France
5. Oxford Centre for Molecular Sciences, New Chemistry Building, South Parks Road, Oxford OX1 3QT, UK

Correspondence to: David I. Stuart^1,5 Correspondence and requests for materials should be addressed to D.I.S. (e-mail: Email: dave@biop.ox.ac.uk). The coordinates have been deposited with the Protein DataBank (accession number 2btv).

Abstract

The structure of the core particle of bluetongue virus has been determined by X-ray crystallography at a resolution approaching 3.5 Å. This transcriptionally active compartment, 700 Å in diameter, represents the largest molecular structure determined in such detail. The atomic structure indicates how approximately 1,000 protein components self-assemble, using both the classical mechanism of quasi-equivalent contacts, which are achieved through triangulation, and a different method, which we term geometrical quasi-equivalence.