title: Structure of the central hub of bacteriophage Mu baseplate determined by X-ray crystallography of gp44.
abstract: Bacteriophage Mu is a double-stranded DNA phage that consists of an icosahedral head, a contractile tail with baseplate and six tail fibers, similar to the well-studied T-even phages. The baseplate of bacteriophage Mu, which recognizes and attaches to a host cell during infection, consists of at least eight different proteins. The baseplate protein, gp44, is essential for bacteriophage Mu assembly and the generation of viable phages. To investigate the role of gp44 in baseplate assembly and infection, the crystal structure of gp44 was determined at 2.1A resolution by the multiple isomorphous replacement method. The overall structure of the gp44 trimer is similar to that of the T4 phage gp27 trimer, which forms the central hub of the T4 baseplate, although these proteins share very little primary sequence homology. Based on these data, we confirm that gp44 exists as a trimer exhibiting a hub-like structure with an inner diameter of 25A through which DNA can presumably pass during infection. The molecular surface of the gp44 trimer that abuts the host cell membrane is positively charged, and it is likely that Mu phage interacts with the membrane through electrostatic interactions mediated by gp44.
authors.affiliation: Institute for Protein Research, Osaka University, Yamada-oka Suita, 565-0871, Japan.
authors.forename: Youhei
authors.initials: Y
authors.lastname: Kondou
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kitazawa
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tsuchiya
authors.forename: Eiki
authors.initials: E
authors.lastname: Yamashita
authors.forename: Mineyuki
authors.initials: M
authors.lastname: Mizuguchi
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kawano
authors.forename: Tomitake
authors.initials: T
authors.lastname: Tsukihara
mesh_terms: D000595:Amino Acid Sequence; D010583:Bacteriophage mu / Q000737:chemistry / Q000648:ultrastructure*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics; D017376:Viral Tail Proteins / Q000737:chemistry* / Q000235:genetics
chemical_list: D014764:Viral Proteins; D017376:Viral Tail Proteins; C074855:gene 44 protein, Enterobacteria phage T4