title: Structure of the 13-fold symmetric portal protein of bacteriophage SPP1.
abstract: We have determined the three-dimensional structure of bacteriophage SPP1 portal protein (gp6) using electron microscopy at liquid-helium temperatures and angular reconstitution. The 13-fold symmetric gp6 oligomer is a turbine-shaped structure with three distinct regions: a conical stem with a central channel; the turbine wings region; and a fringe of small 'tentacles' at the end of the channel exposed to the viral head interior. The tentacle region appears flexible and may be associated with a particular function - sensing when the correct amount of DNA has been packaged. The three-dimensional structure of the gp6 SizA mutant, which packages a smaller chromosome, reveals significant differences in that region.
authors.affiliation: Imperial College of Science, Technology and Medicine, Wolfson Laboratories, Department of Biochemistry, London SW7 2AY, UK.
authors.forename: E V
authors.initials: EV
authors.lastname: Orlova
authors.forename: P
authors.initials: P
authors.lastname: Dube
authors.forename: E
authors.initials: E
authors.lastname: Beckmann
authors.forename: F
authors.initials: F
authors.lastname: Zemlin
authors.forename: R
authors.initials: R
authors.lastname: Lurz
authors.forename: T A
authors.initials: TA
authors.lastname: Trautner
authors.forename: P
authors.initials: P
authors.lastname: Tavares
authors.forename: M
authors.initials: M
authors.lastname: van Heel
mesh_terms: D017103:Bacillus Phages / Q000737:chemistry* / Q000502:physiology; D001704:Biopolymers; D004279:DNA, Viral / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D017906:Siphoviridae / Q000737:chemistry* / Q000502:physiology; D013329:Structure-Activity Relationship; D013696:Temperature; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D019065:Virus Assembly
chemical_list: D001704:Biopolymers; D004279:DNA, Viral; D014764:Viral Proteins; C115880:portal protein, Bacteriophage SPP1