title: Dodecamer rotor ring defines H+/ATP ratio for ATP synthesis of prokaryotic V-ATPase from Thermus thermophilus.
abstract: ATP synthesis by V-ATPase from the thermophilic bacterium Thermus thermophilus driven by the acid-base transition was investigated. The rate of ATP synthesis increased in parallel with the increase in proton motive force (PMF) >110 mV, which is composed of a difference in proton concentration (DeltapH) and the electrical potential differences (DeltaPsi) across membranes. The optimum rate of synthesis reached 85 s(-1), and the H(+)/ATP ratio of 4.0 +/- 0.1 was obtained. ATP was synthesized at a considerable rate solely by DeltapH, indicating DeltaPsi was not absolutely required for synthesis. Consistent with the H(+)/ATP ratio, cryoelectron micrograph images of 2D crystals of the membrane-bound rotor ring of the V-ATPase at 7.0-A resolution showed the presence of 12 V(o)-c subunits, each composed of two transmembrane helices. These results indicate that symmetry mismatch between the rotor and catalytic domains is not obligatory for rotary ATPases/synthases.
authors: Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors: Masashi
authors: M
authors: Toei
authors: Christoph
authors: C
authors: Gerle
authors: Masahiro
authors: M
authors: Nakano
authors: Kazutoshi
authors: K
authors: Tani
authors: Nobuhiko
authors: N
authors: Gyobu
authors: Masatada
authors: M
authors: Tamakoshi
authors: Nobuhito
authors: N
authors: Sone
authors: Masasuke
authors: M
authors: Yoshida
authors: Yoshinori
authors: Y
authors: Fujiyoshi
authors: Kaoru
authors: K
authors: Mitsuoka
authors: Ken
authors: K
authors: Yokoyama
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D020134:Catalytic Domain; D020285:Cryoelectron Microscopy; D003460:Crystallization; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D021122:Protein Subunits / Q000737:chemistry; D016963:Thermus thermophilus / Q000201:enzymology*; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D006859:Hydrogen; D000255:Adenosine Triphosphate; D025262:Vacuolar Proton-Translocating ATPases