title: Tail-associated structural protein gp61 of Staphylococcus aureus phage phi MR11 has bifunctional lytic activity.
abstract: A tailed bacteriophage, phi MR11 (siphovirus), was selected as a candidate therapeutic phage against Staphylococcus aureus infections. Gene 61, one of the 67 ORFs identified, is located in the morphogenic module. The gene product (gp61) has lytic domains homologous to CHAP (corresponding to an amidase function) at its N-terminus and lysozyme subfamily 2 (LYZ2) at its C-terminus. Each domain of gp61 was purified as a recombinant protein. Both the amidase [amino acids (aa) 1-150] and the lysozyme (aa 401-624) domains but not the linker domain (aa 151-400) caused efficient lysis of S. aureus. Immunoelectron microscopy localized gp61 to the tail tip of the phi MR11 phage. These data strongly suggest that gp61 is a tail-associated lytic factor involved in local cell-wall degradation, allowing the subsequent injection of phi MR11 DNA into the host cytoplasm. Staphylococcus aureus lysogenized with phi MR11 was also lysed by both proteins. Staphylococcus aureus strains on which phi MR11 phage can only produce spots but not plaques were also lysed by each protein, indicating that gp61 may be involved in 'lysis from without'. This is the first report of the presence of a tail-associated virion protein that acts as a lysin, in an S. aureus phage.
authors.affiliation: Department of Microbiology and Infection, Kochi Medical School, Nankoku, Kochi, Japan.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Rashel
authors.forename: Jumpei
authors.initials: J
authors.lastname: Uchiyama
authors.forename: Iyo
authors.initials: I
authors.lastname: Takemura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hoshiba
authors.forename: Takako
authors.initials: T
authors.lastname: Ujihara
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Takatsuji
authors.forename: Koichi
authors.initials: K
authors.lastname: Honke
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Matsuzaki
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D001433:Bacteriolysis; D003001:Cloning, Molecular; D016253:Microscopy, Immunoelectron; D009113:Muramidase / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013204:Staphylococcus Phages / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000187:drug effects; D015678:Viral Structural Proteins / Q000378:metabolism*; D014771:Virion / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D015678:Viral Structural Proteins; D009113:Muramidase; D000581:Amidohydrolases; C019665:amidase