Rotational fluctuation of the sodium-driven flagellar motor of Vibrio alginolyticus induced by binding of inhibitors.
Rotation of the Na(+)-driven flagellar motor of Vibrio alginolyticus was investigated under the influence of inhibitors specific to the motor, amiloride and phenamil. The rotation rate of a single flagellum on a cell stuck to a glass slide was examined using laser dark-field microscopy. In the presence of 50 mM NaCl, the average rotation rate (omega) was about 600 r.p.s. with a standard deviation (sigma omega) of 9% of omega. When omega was decreased to about 200 r.p.s. by the presence of 1.5 mM amiloride, sigma omega increased to 15% of omega. On the other hand, when omega was decreased to about 200 r.p.s. by the addition of 0.6 microM phenamil, a large increase in sigma omega up to 50% of omega, was observed. Similarly large fluctuations were observed at other concentrations of phenamil. These observations suggest that dissociation of phenamil from the motor was much slower than that of amiloride. A very low concentration of phenamil caused a transient but substantial reduction in rotation rate. This might suggest that binding of only a single molecule of phenamil strongly inhibits the torque generation in the flagellar motor.
Muramoto
K
K
Department of Molecular Biology, Faculty of Science, Nagoya University, Japan.
Magariyama
Y
Y
Homma
M
M
Kawagishi
I
I
Sugiyama
S
S
Imae
Y
Y
Kudo
S
S
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D003198:Computer Simulation; D005407:Flagella / Q000378:metabolism / Q000502:physiology*; D008853:Microscopy; D008954:Models, Biological; D015394:Molecular Structure; D009068:Movement / Q000187:drug effects; D011485:Protein Binding; D012964:Sodium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000187:drug effects; D014733:Vibrio / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
D026941:Sodium Channel Blockers; D015222:Sodium Channels; C047088:phenylamil; D000584:Amiloride; D012964:Sodium