Crystal structure of the DNA-recognition component of the bacterial virus Sf6 genome-packaging machine.
In herpesviruses and many bacterial viruses, genome-packaging is a precisely mediated process fulfilled by a virally encoded molecular machine called terminase that consists of two protein components: A DNA-recognition component that defines the specificity for packaged DNA, and a catalytic component that provides energy for the packaging reaction by hydrolyzing ATP. The terminase docks onto the portal protein complex embedded in a single vertex of a preformed viral protein shell called procapsid, and pumps the viral DNA into the procapsid through a conduit formed by the portal. Here we report the 1.65 A resolution structure of the DNA-recognition component gp1 of the Shigella bacteriophage Sf6 genome-packaging machine. The structure reveals a ring-like octamer formed by interweaved protein monomers with a highly extended fold, embracing a tunnel through which DNA may be translocated. The N-terminal DNA-binding domains form the peripheral appendages surrounding the octamer. The central domain contributes to oligomerization through interactions of bundled helices. The C-terminal domain forms a barrel with parallel beta-strands. The structure reveals a common scheme for oligomerization of terminase DNA-recognition components, and provides insights into the role of gp1 in formation of the packaging-competent terminase complex and assembly of the terminase with the portal, in which ring-like protein oligomers stack together to form a continuous channel for viral DNA translocation.
Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA.
Haiyan
H
Zhao
Casey J
CJ
Finch
Reuben D
RD
Sequeira
Brian A
BA
Johnson
John E
JE
Johnson
Sherwood R
SR
Casjens
Liang
L
Tang
D018360:Crystallography, X-Ray; D042003:DNA Packaging; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D016679:Genome, Viral; D046911:Macromolecular Substances; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D017902:Podoviridae / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012763:Shigella flexneri / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D019065:Virus Assembly
D004279:DNA, Viral; D046911:Macromolecular Substances; D014764:Viral Proteins; D004706:Endodeoxyribonucleases; C030894:terminase