Stator assembly and activation mechanism of the flagellar motor by the periplasms region of MotB

Seiji Kojima, Katsumi Imada, Mayuko Sakuma, Yuki Sudo, Chojiro Kojima, Tohru Minamino, Michio Homma, Keiichi Namba

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94 Citations (Scopus)


Torque generation in the Salmonella flagellar motor is coupled to translocation of H+ ions through the protonconducting 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 (MotBc) 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 MotBc are required both for PG binding and the proton channel activation.

Original languageEnglish
Pages (from-to)710-718
Number of pages9
JournalMolecular Microbiology
Issue number4
Publication statusPublished - Aug 2009
Externally publishedYes


ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

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