Binding of an intrinsic ATPase inhibitor to the F(1)FoATPase in phosphorylating conditions of yeast mitochondria.
Yeast mitochondrial ATP synthase has three regulatory proteins; ATPase inhibitor, 9K protein, and 15K protein. A mutant yeast lacking these three regulatory factors was constructed by gene disruption. Rates of ATP synthesis of both wild-type and the mutant yeast mitochondria decreased with decrease of respiration, while their membrane potential was maintained at 170-160 mV under various respiration rates. When mitochondrial respiration was blocked by antimycin A, the membrane potential of both types of mitochondria was maintained at about 160 mV by ATP hydrolysis. ATP hydrolyzing activity of F(1)FoATPase solubilized from normal mitochondria decreased in proportion to the rate of ATP synthesis, while the activity of the mutant F(1)FoATPase was constant regardless of changes in the rate of phosphorylation. These observations strongly suggest that F(1)FoATPase in the phosphorylating mitochondria is a mixture of two types of enzyme, phosphorylating and non-phosphorylating enzymes, whose ratio is determined by the rate of respiration and that the ATPase inhibitor binds preferentially to the non-phosphorylating enzyme.
Iwatsuki
H
H
Department of Applied Chemistry, Muroran Institute of Technology, Muroran, Hokkaido 050-8585, Japan.
Lu
Y M
YM
Yamaguchi
K
K
Ichikawa
N
N
Hashimoto
T
T
D000255:Adenosine Triphosphate / Q000096:biosynthesis / Q000378:metabolism; D000968:Antimycin A / Q000378:metabolism / Q000494:pharmacology; D019069:Cell Respiration / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D017353:Gene Deletion; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
D004791:Enzyme Inhibitors; D000968:Antimycin A; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases