title: Cryo-electron microscopy reveals the functional organization of an enveloped virus, Semliki Forest virus.
abstract: Semliki Forest virus serves as a paradigm for membrane fusion and assembly. Our icosahedral reconstruction combined 5276 particle images from 48 cryo-electron micrographs and determined the virion structure to 9 A resolution. The improved resolution of this map reveals an N-terminal arm linking capsid subunits and defines the spike-capsid interaction sites. It illustrates the paired helical nature of the transmembrane segments and the elongated structures connecting them to the spike projecting domains. A 10 A diameter density in the fusion protein lines the cavity at the center of the spike. These clearly visible features combine with the variation in order between the layers to provide a framework for understanding the structural changes during the life cycle of an enveloped virus.
authors.affiliation: The Structural Biology Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
authors.forename: E J
authors.initials: EJ
authors.lastname: Mancini
authors.forename: M
authors.initials: M
authors.lastname: Clarke
authors.forename: B E
authors.initials: BE
authors.lastname: Gowen
authors.forename: T
authors.initials: T
authors.lastname: Rutten
authors.forename: S D
authors.initials: SD
authors.lastname: Fuller
mesh_terms: D020285:Cryoelectron Microscopy; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D008961:Models, Structural; D019251:Nucleocapsid / Q000648:ultrastructure*; D012672:Semliki forest virus / Q000648:ultrastructure*