期刊
JOURNAL OF BIOENERGETICS AND BIOMEMBRANES
卷 34, 期 4, 页码 269-278出版社
SPRINGER/PLENUM PUBLISHERS
DOI: 10.1023/A:1020252401675
关键词
ATP synthase; Paracoccus denitrificans; sulfite; membrane vesicles; inhibition; activation
The F1F0 complex of Paracoccus denitrificans (PdF1F0) is the fastest ATP synthase but the slowest ATPase. Sulfite exerts maximal activation of the PdF1F0-ATPase (Pacheco-Moises, F., Garcia, J. J., Rodriguez-Zavala, J. S., and Moreno-Sanchez, R. (2000). Eur. J. Biochem. 267, 993-1000) but its effect on the PdF1F0-ATP synthase activity remains unknown. Therefore, we studied the effect of sulfite on ATP synthesis and (32)Pi <-> ATP exchange reactions of inside-out membrane vesicles of P. denitrificans. Sulfite inhibited both reactions under conditions of maximal DeltapH and normal sensitivity to dicyclohexylcarbodiimide. Sulfite increased by 10- and 5-fold the K-0.5 for Mg2+-ADP and Pi during ATP synthesis, respectively, and by 4-fold the IC50 of Mg2+-ADP for inhibition of the PdF1F0-ATPase activity. Thus, sulfite exerts opposite effects on the forward and reverse functioning of the PdF1F0 complex. These effects are not due to membrane or PdF1F0 uncoupling. Kinetic and structural modifications that could account for these results are discussed.
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