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  • Title: Dodecamer rotor ring defines H+/ATP ratio for ATP synthesis of prokaryotic V-ATPase from Thermus thermophilus.
    Author: Toei M, Gerle C, Nakano M, Tani K, Gyobu N, Tamakoshi M, Sone N, Yoshida M, Fujiyoshi Y, Mitsuoka K, Yokoyama K.
    Journal: Proc Natl Acad Sci U S A; 2007 Dec 18; 104(51):20256-61. PubMed ID: 18077374.
    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.
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