title: Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor.
abstract: The flagellar motor of Bacillus subtilis possesses two distinct H+-type MotAB and Na+-type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner.
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Terahara
authors.affiliation: Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Oura-gun, Gunma 374-0193, Japan.
authors.forename: Yukina
authors.initials: Y
authors.lastname: Noguchi
authors.affiliation: Department of Applied Physics, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Nobunori
authors.initials: N
authors.lastname: Kami-Ike
authors.affiliation: Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Oura-gun, Gunma 374-0193, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ito
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.|Quantitative Biology Center, RIKEN, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D019415:Torque; D014783:Viscosity
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; D011134:Polysaccharides; D012964:Sodium