Flagellar rotation in the archaeon Halobacterium salinarum depends on ATP.
Halobacterium salinarum swims with the help of a polarly inserted flagellar bundle. In energized cells, the flagellar motors rotate continuously, occasionally switching the rotational sense. Starving cells become immotile as the energy level drops. Presumably, there is a threshold of energy required for flagellar rotation. When starved, immotile cells are energized by exposure to light, the speed of flagellar rotation increases gradually to its steady state over several minutes. Since the light-driven proton pump bacteriorhodopsin energizes the cell membrane to the maximal level within a fraction of a second, the delay in reaching the maximal swimming speed suggests that the halobacterial flagellar motor may not be driven directly by proton motive force. Swimming cells, which obtain their energy exclusively through light-driven proton pumping, become immotile within 20 min when treated with N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of the proton translocating ATP synthase. However, flagellar motility in DCCD-treated cells can be restored by the addition of L-arginine, which serves as a fermentative energy source and restores the cytoplasmic ATP level in the presence of DCCD. This suggests that flagellar motor rotation depends on ATP, and this is confirmed by the observation that motility is increased strongly by L-arginine at zero proton motive force levels. The flagellar motor may be driven either by ATP directly or by an ATP-generated ion gradient that is not coupled directly to the proton gradient or the proton motive force of the cell.
Streif
Stefan
S
Max Planck Institute of Biochemistry, Martinsried, Germany.
Staudinger
Wilfried Franz
WF
Marwan
Wolfgang
W
Oesterhelt
Dieter
D
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000693:Anaerobiosis / Q000187:drug effects / Q000528:radiation effects; D001120:Arginine / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D005407:Flagella / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D019617:Halobacterium salinarum / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008027:Light; D008564:Membrane Potentials / Q000187:drug effects / Q000528:radiation effects; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D012399:Rotation
D020409:Molecular Motor Proteins; D004024:Dicyclohexylcarbodiimide; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate; D001120:Arginine; D006180:Proton-Translocating ATPases