Torque-speed relationship of the Na+-driven flagellar motor of Vibrio alginolyticus.
The torque-speed relationship of the Na(+)-driven flagellar motor of Vibrio alginolyticus was investigated. The rotation rate of the motor was measured by following the position of a bead, attached to a flagellar filament, using optical nanometry. In the presence of 50mM NaCl, the generated torque was relatively constant ( approximately 3800pNnm) at lower speeds (speeds up to approximately 300Hz) and then decreased steeply, similar to the H(+)-driven flagellar motor of Escherichia coli. When the external NaCl concentration was varied, the generated torque of the flagellar motor was changed over a wide range of speeds. This result could be reproduced using a simple kinetic model, which takes into consideration the association and dissociation of Na(+) onto the motor. These results imply that for a complete understanding of the mechanism of flagellar rotation it is essential to consider both the electrochemical gradient and the absolute concentration of the coupling ion.
Sowa
Yoshiyuki
Y
Department of Biophysical Engineering, Osaka University, 1-3, Machikaneyama, Toyonaka, 560-8531, Osaka, Japan.
Hotta
Hiroyuki
H
Homma
Michio
M
Ishijima
Akihiko
A
D003470:Culture Media; D005407:Flagella / Q000502:physiology*; D012964:Sodium / Q000502:physiology*; D014733:Vibrio / Q000502:physiology*
D003470:Culture Media; D012964:Sodium