Epsilon subunit, an endogenous inhibitor of bacterial F(1)-ATPase, also inhibits F(0)F(1)-ATPase.
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.
Kato-Yamada
Y
Y
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503, Japan.
Bald
D
D
Koike
M
M
Motohashi
K
K
Hisabori
T
T
Yoshida
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006868:Hydrolysis; D007700:Kinetics; D008081:Liposomes; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D000097795:ATPase Inhibitory Protein
D000255:Adenosine Triphosphate; D001426:Bacterial Proteins; D008081:Liposomes; D011506:Proteins; D006180:Proton-Translocating ATPases; D000097795:ATPase Inhibitory Protein