title: Stator assembly and activation mechanism of the flagellar motor by the periplasmic region of MotB.
abstract: Torque generation in the Salmonella flagellar motor is coupled to translocation of H(+) ions through the proton-conducting channel of the Mot protein stator complex. The Mot complex is believed to be anchored to the peptidoglycan (PG) layer by the putative peptidoglycan-binding (PGB) domain of MotB. Proton translocation is activated only when the stator is installed into the motor. We report the crystal structure of a C-terminal periplasmic fragment of MotB (MotB(C)) that contains the PGB domain and includes the entire periplasmic region essential for motility. Structural and functional analyses indicate that the PGB domains must dimerize in order to form the proton-conducting channel. Drastic conformational changes in the N-terminal portion of MotB(C) are required both for PG binding and the proton channel activation.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kojima
authors.forename: Katsumi
authors.initials: K
authors.lastname: Imada
authors.forename: Mayuko
authors.initials: M
authors.lastname: Sakuma
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sudo
authors.forename: Chojiro
authors.initials: C
authors.lastname: Kojima
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
authors.forename: Michio
authors.initials: M
authors.lastname: Homma
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm / Q000378:metabolism; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; C064779:MotB protein, Bacteria