Crystal structure of the DNA-recognition component of the bacterial virus Sf6 genome-packaging machine

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 5; pp. 1971 - 1976
• Main Authors: Zhao, Haiyan, Finch, Casey J, Sequeira, Reuben D, Johnson, Brian A, Johnson, John E, Casjens, Sherwood R, Tang, Liang
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 02.02.2010; National Acad Sciences
• Subjects: Bacterial proteins; Bacteriophage lambda; Bacteriophage T4; Bacteriophages; Binding sites; Biological Sciences; Crystallography, X-Ray; Deoxyribonucleic acid; DNA; DNA Packaging; DNA, Viral - chemistry; DNA, Viral - genetics; DNA, Viral - metabolism; Endodeoxyribonucleases - chemistry; Endodeoxyribonucleases - genetics; Endodeoxyribonucleases - physiology; Endodeoxyribonucleases - ultrastructure; Genome, Viral; Genomics; Herpes viruses; Macromolecular Substances; Microscopy, Electron, Transmission; Models, Molecular; Molecular interactions; Molecular structure; Molecules; Monomers; Nucleic Acid Conformation; Packaging; Podoviridae - chemistry; Podoviridae - genetics; Podoviridae - physiology; Protein Structure, Quaternary; Protein Structure, Tertiary; Proteins; Shigella flexneri - virology; Viral DNA; Viral Proteins - chemistry; Viral Proteins - genetics; Viral Proteins - physiology; Viral Proteins - ultrastructure; Virus Assembly
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0908569107

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 Å 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.