title: Mapping of functional sites on the primary structure of the contractile tail sheath protein of bacteriophage T4 by mutation analysis.
abstract: In order to determine the functional roles of amino acid residues in gp18 (gp: gene product), the contractile tail sheath protein of bacteriophage T4, the mutation sites and amino acid replacements of available and newly created missense mutants with distinct phenotypes were determined. Amber mutants were also utilized for amino acid insertion by host amber suppressor cell strains. It was found that mutants that gave rise to a particular phenotype were mapped in a particular region along the polypeptide chain. Namely, all amino acid replacements in the cold-sensitive mutants (cs, which grows at 37 degrees C, but not at 25 degrees C) and the heat-sensitive mutant (hs, lose viability by incubation at 55 degrees C for 30 min) except for one hs mutant were mapped in a limited region in the C-terminal domain. On the other hand, all the temperature-sensitive mutants (ts, grow at 30 degrees C, but not at 42 degrees C) and carbowax mutants (CBW, can adsorb to the host bacterium in the presence of high concentrations of polyethylene glycol, where wild-type phage cannot) were mapped in the N-terminal protease-resistant domain, except for one ts mutant. The results suggested that the C-terminal region of gp18 is important for contraction and assembly, whereas the N-terminal protease-resistant domain constitutes the protruding part of the tail sheath.
authors.affiliation: Department of Nano-Material Systems, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeda
authors.forename: Makoto
authors.initials: M
authors.lastname: Suzuki
authors.forename: Takahito
authors.initials: T
authors.lastname: Yamada
authors.forename: Manabu
authors.initials: M
authors.lastname: Kageyama
authors.forename: Fumio
authors.initials: F
authors.lastname: Arisaka
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017122:Bacteriophage T4 / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020125:Mutation, Missense; D010641:Phenotype; D011092:Polyethylene Glycols; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D017376:Viral Tail Proteins / Q000737:chemistry* / Q000235:genetics; D014779:Virus Replication
chemical_list: D017376:Viral Tail Proteins; C402835:glycoprotein 18, bacteriophage T4; D011092:Polyethylene Glycols