title: The birnavirus crystal structure reveals structural relationships among icosahedral viruses.
abstract: Double-stranded RNA virions are transcriptionally competent icosahedral particles that must translocate across a lipid bilayer to function within the cytoplasm of the target cell. Birnaviruses are unique among dsRNA viruses as they have a single T = 13 icosahedral shell, lacking the characteristic inner capsid observed in the others. We determined the crystal structures of the T = 1 subviral particle (260 angstroms in diameter) and of the T = 13 intact virus particle (700 angstroms in diameter) of an avian birnavirus to 3 angstroms and 7 angstroms resolution, respectively. Our results show that VP2, the only component of the virus icosahedral capsid, is homologous both to the capsid protein of positive-strand RNA viruses, like the T = 3 nodaviruses, and to the T = 13 capsid protein of members of the Reoviridae family of dsRNA viruses. Together, these results provide important insights into the multiple functions of the birnavirus capsid and reveal unexpected structural relationships among icosahedral viruses.
authors.affiliation: Laboratoire de Virologie Moléculaire et Structurale, UMR 2472/1157 CNRS-INRA and IFR 115, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Fasséli
authors.initials: F
authors.lastname: Coulibaly
authors.forename: Christophe
authors.initials: C
authors.lastname: Chevalier
authors.forename: Irina
authors.initials: I
authors.lastname: Gutsche
authors.forename: Joan
authors.initials: J
authors.lastname: Pous
authors.forename: Jorge
authors.initials: J
authors.lastname: Navaza
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bressanelli
authors.forename: Bernard
authors.initials: B
authors.lastname: Delmas
authors.forename: Félix A
authors.initials: FA
authors.lastname: Rey
mesh_terms: D000595:Amino Acid Sequence; D018059:Birnaviridae / Q000737:chemistry*; D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry*; D003198:Computer Simulation; D003460:Crystallization; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D021122:Protein Subunits / Q000737:chemistry; D012087:Reoviridae / Q000737:chemistry*
chemical_list: D036022:Capsid Proteins; D021122:Protein Subunits