Structure of bacteriophage SPP1 head-to-tail connection reveals mechanism for viral DNA gating

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 21; pp. 8507 - 8512
• Main Authors: Lhuillier, Sophie, Gallopin, Matthieu, Gilquin, Bernard, Brasilès, Sandrine, Lancelot, Nathalie, Letellier, Guillaume, Gilles, Mathilde, Dethan, Guillaume, Orlova, Elena V, Couprie, Joël, Tavares, Paulo, Zinn-Justin, Sophie
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 26.05.2009; National Acad Sciences
• Series: From the Cover
• Subjects: Bacteria; Bacteriology; Bacteriophages; Bacteriophages - chemistry; Bacteriophages - genetics; Bacteriophages - metabolism; Bacteriophages - ultrastructure; Biological Sciences; Biological Transport; Capsid; Capsids; Cellular Biology; Channel gating; Deoxyribonucleic acid; Disulfides; DNA; DNA viruses; DNA, Viral - genetics; DNA, Viral - metabolism; Genetic research; Genomes; Genomics; Infection; Ionizing radiation; Life Sciences; Microscopy, Electron; Models, Molecular; Monomers; N.M.R; Packaging; Phages; portal protein; Protein Binding; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Viral Proteins - chemistry; Viral Proteins - genetics; Viral Proteins - metabolism; Viral Proteins - ultrastructure; Virions; Viruses; UNSTRUCTURED PROTEINS; NMR; MORPHOGENESE; STRUCTURE DOCKING; VIRUS INFECTION; VIRUS ASSEMBLY
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0812407106

In many bacterial viruses and in certain animal viruses, the double-stranded DNA genome enters and exits the capsid through a portal gatekeeper. We report a pseudoatomic structure of a complete portal system. The bacteriophage SPP1 gatekeeper is composed of dodecamers of the portal protein gp6, the adaptor gp15, and the stopper gp16. The solution structures of gp15 and gp16 were determined by NMR. They were then docked together with the X-ray structure of gp6 into the electron density of the [almost equal to]1-MDa SPP1 portal complex purified from DNA-filled capsids. The resulting structure reveals that gatekeeper assembly is accompanied by a large rearrangement of the gp15 structure and by folding of a flexible loop of gp16 to form an intersubunit parallel β-sheet that closes the portal channel. This stopper system prevents release of packaged DNA. Disulfide cross-linking between β-strands of the stopper blocks the key conformational changes that control genome ejection from the virus at the beginning of host infection.