Epsilon subunit, an endogenous inhibitor of bacterial F(1)-ATPase, also inhibits F(0)F(1)-ATPase.

TitleEpsilon subunit, an endogenous inhibitor of bacterial F(1)-ATPase, also inhibits F(0)F(1)-ATPase.
Publication TypeJournal Article
Year of Publication1999
AuthorsKato-Yamada, Y, Bald, D, Koike, M, Motohashi, K, Hisabori, T, Yoshida, M
JournalJ Biol Chem
Date Published1999 Nov 26
KeywordsAdenosine Triphosphate, Bacillus, Bacterial Proteins, Electrophoresis, Polyacrylamide Gel, Enzyme Stability, Hydrolysis, Kinetics, Liposomes, Proteins, Proton-Translocating ATPases, Time Factors

Since the report by Sternweis and Smith (Sternweis, P. C., and Smith, J. B. (1980) Biochemistry 19, 526-531), the epsilon subunit, an endogenous inhibitor of bacterial F(1)-ATPase, has long been thought not to inhibit activity of the holo-enzyme, F(0)F(1)-ATPase. However, we report here that the epsilon subunit is exerting inhibition in F(0)F(1)-ATPase. We prepared a C-terminal half-truncated epsilon subunit (epsilon(DeltaC)) of the thermophilic Bacillus PS3 F(0)F(1)-ATPase and reconstituted F(1)- and F(0)F(1)-ATPase containing epsilon(DeltaC). Compared with F(1)- and F(0)F(1)-ATPase containing intact epsilon, those containing epsilon(DeltaC) showed uninhibited activity; severalfold higher rate of ATP hydrolysis at low ATP concentration and the start of ATP hydrolysis without an initial lag at high ATP concentration. The F(0)F(1)-ATPase containing epsilon(DeltaC) was capable of ATP-driven H(+) pumping. The time-course of pumping at low ATP concentration was faster than that by the F(0)F(1)-ATPase containing intact epsilon. Thus, the comparison with noninhibitory epsilon(DeltaC) mutant shed light on the inhibitory role of the intact epsilon subunit in F(0)F(1)-ATPase.

Alternate JournalJ. Biol. Chem.
Citation KeyPMID10567363
PubMed ID10567363