Critical evaluation of the one- versus the two-channel model for the operation of the ATP synthase's F(o) motor.
The mechanism of converting an electrochemical gradient of protons or Na(+) ions across the membrane into rotational torque by the F(o) motor of the ATP synthase has been described by a two-channel model or by a one-channel model. Experimental evidence obtained with the F(o) motor from the Propionigenium modestum ATP synthase is described which is in accordance with the one-channel model, but not with the two-channel model. This evidence includes the ATP-dependent occlusion of one (22)Na(+) per ATP synthase with a mutated Na(+)-impermeable a subunit or the Na(+)(in)/(22)Na(+)(out) exchange which is not affected by modifying part of the c subunit sites with dicyclohexylcarbodiimide.
Dimroth
P
P
Institut für Mikrobiologie, Eidgenössische Technische Hochschule, ETH-Zentrum, CH-8092, Zurich, Switzerland. dimroth@micro.bio.ethz.ch
Matthey
U
U
Kaim
G
G
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D001665:Binding Sites; D002412:Cations; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D020409:Molecular Motor Proteins; D011424:Propionibacterium; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D011522:Protons; D012399:Rotation; D012964:Sodium / Q000737:chemistry; D012979:Sodium Radioisotopes
D002412:Cations; D008565:Membrane Proteins; D020409:Molecular Motor Proteins; D011522:Protons; D012979:Sodium Radioisotopes; D000255:Adenosine Triphosphate; D012964:Sodium; D006180:Proton-Translocating ATPases