title: Structure of a viral DNA gatekeeper at 10 A resolution by cryo-electron microscopy.
abstract: In tailed bacteriophages and herpes viruses, the viral DNA is packaged through the portal protein channel. Channel closure is essential to prevent DNA release after packaging. Here we present the connector structure from bacteriophage SPP1 using cryo-electron microscopy and single particle analysis. The multiprotein complex comprises the portal protein gp6 and the head completion proteins gp15 and gp16. Although we show that gp6 in the connector has a fold similar to that of the isolated portal protein, we observe conformational changes in the region of gp6 exposed to the DNA-packaging ATPase and to gp15. This reorganization does not cause closure of the channel. The connector channel traverses the full height of gp6 and gp15, but it is closed by gp16 at the bottom of the complex. Gp16 acts as a valve whose closure prevents DNA leakage, while its opening is required for DNA release upon interaction of the virus with its host.
authors.affiliation: Imperial College of Science, Technology and Medicine, Department of Biological Sciences, Biochemistry Building, London SW7 2AY, UK. e.orlova@mail.cryst.bbk.ac.uk
authors.forename: Elena V
authors.initials: EV
authors.lastname: Orlova
authors.forename: Brent
authors.initials: B
authors.lastname: Gowen
authors.forename: Anja
authors.initials: A
authors.lastname: Dröge
authors.forename: Asita
authors.initials: A
authors.lastname: Stiege
authors.forename: Frank
authors.initials: F
authors.lastname: Weise
authors.forename: Rudi
authors.initials: R
authors.lastname: Lurz
authors.forename: Marin
authors.initials: M
authors.lastname: van Heel
authors.forename: Paulo
authors.initials: P
authors.lastname: Tavares
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D017103:Bacillus Phages / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D001412:Bacillus subtilis / Q000821:virology*; D002213:Capsid / Q000737:chemistry / Q000378:metabolism; D020285:Cryoelectron Microscopy; D004279:DNA, Viral / Q000378:metabolism / Q000648:ultrastructure*; D016253:Microscopy, Immunoelectron; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014764:Viral Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D019065:Virus Assembly
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D000251:Adenosine Triphosphatases