Mitochondrial adenosine triphosphatase of the fission yeast, Schizosaccharomyces pombe 972h-. Changes in activity and inhibitor-sensitivity in response to catabolite repression

Abstract

1. The specific activity of mitochondrial ATPase (adenosine triphosphatase) in extracts of Schizosaccharomycespombe decreased 2.5-fold as the glucose concentration in the growth medium decreased from 50mM to 15mm. 2. During the late exponential phase of growth, ATPase activity doubled. 3. Sensitivity to oligomycin and Dio-9 as measured by values for 15o (pug of inhibitor/mg ofprotein giving 50 % inhibition) at pH 6.8 increased sixfold and ninefold respectively during the initial decrease in ATPase activity, and this degree of sensitivity was maintained for the remainder of the growth cycle. 4. Increased sensitivity to NN'-dicyclohexylcarbodi-imide, triethyltin and venturicidin was also observed during the early stage of glucose de-repression. 5. Smaller increases in sensitivity to efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin and spegazzinine also occurred. 6. The ATPase of glycerol-grown cells was less sensitive to inhibitors than-that of glucose-repressed cells; change in values for I50 were not so marked during the growth cycle of cells growing with glycerol. 7. When submitochondrial particles from glycerol-grown cells were treated by passage through Sephadex G-50, a fourfold increase in activity was accompanied by increased inhibitor resistance. 8. Gel filtration of submitochondrial particles from glucose-de-repressed cells gave similar results, whereas loss of ATPase occurred in submitochondrial particles from glucose-repressed cells. 9. It is proposed that alterations in sensitivity to inhibitors at different stages of glucose derepression may be partly controlled by a naturally occurring inhibitor of ATPase. 10. The inhibitors tested may be classified into two groups on the basis of alterations of sensitivity of the ATPase during physiological modification: (a) oligomycin, Dio-9, NN'-dicyclohexylcarbodi-imide, venturicidin and triethyltin, and (b) efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin and spegazzimne.

ATP Synthase and the Actions of Inhibitors Utilized To Study Its Roles in Human Health, Disease, and Other Scientific Areas

“…Spegazzinine inhibits both cyclic and noncyclic photophosphorylation of isolated spinach chloroplasts. It also inhibits the mitochondrial ATPase activity of S. pombe (234) and slightly inhibits the mitochondrial ATPase activity of Tetrahymena pyriformis ST (404). In contrast, spegazzinine has no inhibitory effects on the ATPase activities of ATP synthases from Clostridium pasteurianum (78), Tritrichomonas foetus (235), and mitochondria of Crithidia fasciculata (439).…”

Chronic quercetin exposure affects fatty acid catabolism in rat lung

“…Mechanistic insights on how quercetin can modulate fatty acid metabolism come from studies using models that show direct actions of quercetin on enzyme activities or indirect activation of regulating factors. Firstly, quercetin was shown to inhibit ATP synthase resulting in decreased mitochondrial and cellular ATP levels [56][57][58][59]. NAD + /NADH ratios were also affected by quercetin in isolated perfused liver [60,61].…”

Adenosine Triphosphatase Activity of Tritrichomonas foetus

“…The concentrations used were greatly in excess of the I,, values previously determined for the mitochondria1 ATPase of yeast (Lloyd & Edwards, 1976. At the optimum pH, I?,"-dicylohexylcarbodi-imide [20 pg (mg protein)-l] stimulated activity by 21 % whereas slight inhibition was observed at pH values below 6-3.…”