title: Structure of a Bacterial Virus DNA-Injection Protein Complex Reveals a Decameric Assembly with a Constricted Molecular Channel.
abstract: The multi-layered cell envelope structure of Gram-negative bacteria represents significant physical and chemical barriers for short-tailed phages to inject phage DNA into the host cytoplasm. Here we show that a DNA-injection protein of bacteriophage Sf6, gp12, forms a 465-kDa, decameric assembly in vitro. The electron microscopic structure of the gp12 assembly shows a ~150-Å, mushroom-like architecture consisting of a crown domain and a tube-like domain, which embraces a 25-Å-wide channel that could precisely accommodate dsDNA. The constricted channel suggests that gp12 mediates rapid, uni-directional injection of phage DNA into host cells by providing a molecular conduit for DNA translocation. The assembly exhibits a 10-fold symmetry, which may be a common feature among DNA-injection proteins of P22-like phages and may suggest a symmetry mismatch with respect to the 6-fold symmetric phage tail. The gp12 monomer is highly flexible in solution, supporting a mechanism for translocation of the protein through the conduit of the phage tail toward the host cell envelope, where it assembles into a DNA-injection device.
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Zhao
authors.affiliation: National Resource for Automated Molecular Microscopy, The Scripps Research Institute, La Jolla, California, United States of America.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Speir
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 14 2575 Sand Hill Road, MS69, Menlo Park, California, United States of America.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Zihan
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Lingfei
authors.initials: L
authors.lastname: Liang
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Anna Y
authors.initials: AY
authors.lastname: Lynn
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Brittany
authors.initials: B
authors.lastname: Varnado
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 14 2575 Sand Hill Road, MS69, Menlo Park, California, United States of America.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Weiss
authors.affiliation: Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, Kansas, United States of America.
authors.forename: Liang
authors.initials: L
authors.lastname: Tang
mesh_terms: D001435:Bacteriophages / Q000235:genetics*; D004279:DNA, Viral / Q000737:chemistry*; D021621:Imaging, Three-Dimensional; D008958:Models, Molecular; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012996:Solutions; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004279:DNA, Viral; D012996:Solutions; D014764:Viral Proteins