title: Crystal structure and location of gp131 in the bacteriophage phiKZ virion.
abstract: Pseudomonas phage ϕKZ and its two close relatives ϕPA3 and 201ϕ2-1 are very large bacteriophages that form a separate branch in phage classification because their genomes are very different from the rest of GenBank sequence data. The contractile tail of ϕKZ is built from at least 32 different proteins, but a definitive structural function is assigned to only one of them-the tail sheath protein. Here, we report the crystal structure of the C-terminal domain of another phiKZ tail protein, gene product 131 (gp131C). We show that gp131 is located at the periphery of the baseplate and possibly associates with fibers that emanate from the baseplate. Gp131C is a seven-bladed β-propeller that has a shape of a skewed toroid. A small but highly conserved and negatively charged patch on the surface of gp131C might be important for substrate binding or for interaction with a different tail protein.
authors.affiliation: École Polytechnique Fédérale de Lausanne, Laboratory of Structural Biology and Biophysics, BSP-415, 1015 Lausanne, Switzerland.
authors.forename: Lada V
authors.initials: LV
authors.lastname: Sycheva
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Shneider
authors.forename: Nina N
authors.initials: NN
authors.lastname: Sykilinda
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ivanova
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Miroshnikov
authors.forename: Petr G
authors.initials: PG
authors.lastname: Leiman
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D016253:Microscopy, Immunoelectron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011549:Pseudomonas / Q000648:ultrastructure / Q000821:virology*; D017105:Pseudomonas Phages / Q000737:chemistry*; D015678:Viral Structural Proteins / Q000032:analysis*; D014771:Virion / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D015678:Viral Structural Proteins