Synthesis and hydrolysis of ATP by the mitochondrial ATP synthase

1988 ◽  
Vol 66 (7) ◽  
pp. 677-682 ◽  
Author(s):  
M. Tuena de Gômez-Puyou ◽  
Orlando B. Martins ◽  
A. Gômez-Puyou
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Control Synthesis ◽  
Inhibitor Protein ◽  
Atpase Inhibitor ◽  
Mitochondrial Atp Synthase ◽  
High Concentrations ◽  
Hydrolysis Of

A brief summary of the factors that control synthesis and hydrolysis of ATP by the mitochondrial H+-ATP synthase is made. Particular emphasis is placed on the role of the natural ATPase inhibitor protein. It is clear from the existing data obtained with a number of agents that there is no correlation between variations of the rate of ATP hydrolysis and ATP synthesis as driven by respiration. The mechanism by which each condition differentially affects the two activities is not entirely known. For the case of the natural ATPase inhibitor protein, it appears that the protein controls the kinetics of the enzyme. This control seems essential for achieving maximal accumulation of ATP during electron transport in systems that contain relatively high concentrations of ATP.

scholarly journals Targeting Mycobacterial F-ATP Synthase C-Terminal α Subunit Interaction Motif on Rotary Subunit γ

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Amaravadhi Harikishore ◽  
Chui-Fann Wong ◽  
Priya Ragunathan ◽  
Dennis Litty ◽  
Volker Müller ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Α Subunit ◽  
Rotational States ◽  
C Terminus ◽  
Inverted Membrane Vesicles ◽  
Hydrolysis Of ◽  
Micromolar Range

Mycobacteria regulate their energy (ATP) levels to sustain their survival even in stringent living conditions. Recent studies have shown that mycobacteria not only slow down their respiratory rate but also block ATP hydrolysis of the F-ATP synthase (α3:β3:γ:δ:ε:a:b:b’:c9) to maintain ATP homeostasis in situations not amenable for growth. The mycobacteria-specific α C-terminus (α533-545) has unraveled to be the major regulative of latent ATP hydrolysis. Its deletion stimulates ATPase activity while reducing ATP synthesis. In one of the six rotational states of F-ATP synthase, α533-545 has been visualized to dock deep into subunit γ, thereby blocking rotation of γ within the engine. The functional role(s) of this C-terminus in the other rotational states are not clarified yet and are being still pursued in structural studies. Based on the interaction pattern of the docked α533-545 region with subunit γ, we attempted to study the druggability of the α533-545 motif. In this direction, our computational work has led to the development of an eight-featured α533-545 peptide pharmacophore, followed by database screening, molecular docking, and pose selection, resulting in eleven hit molecules. ATP synthesis inhibition assays using recombinant ATP synthase as well as mycobacterial inverted membrane vesicles show that one of the hits, AlMF1, inhibited the mycobacterial F-ATP synthase in a micromolar range. The successful targeting of the α533-545-γ interaction motif demonstrates the potential to develop inhibitors targeting the α site to interrupt rotary coupling with ATP synthesis.

scholarly journals Deleting the IF 1 -like ζ subunit from Paracoccus denitrificans ATP synthase is not sufficient to activate ATP hydrolysis

Open Biology ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 170206 ◽  
Author(s):  
Febin Varghese ◽  
James N. Blaza ◽  
Andrew J. Y. Jones ◽  
Owen D. Jarman ◽  
Judy Hirst
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Paracoccus Denitrificans ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Inhibitor Protein ◽  
Wild Type ◽  
Efficient Energy ◽  
Inverted Membrane Vesicles ◽  
Atp Synthases

In oxidative phosphorylation, ATP synthases interconvert two forms of free energy: they are driven by the proton-motive force across an energy-transducing membrane to synthesize ATP and displace the ADP/ATP ratio from equilibrium. For thermodynamically efficient energy conversion they must be reversible catalysts. However, in many species ATP synthases are unidirectional catalysts (their rates of ATP hydrolysis are negligible), and in others mechanisms have evolved to regulate or minimize hydrolysis. Unidirectional catalysis by Paracoccus denitrificans ATP synthase has been attributed to its unique ζ subunit, which is structurally analogous to the mammalian inhibitor protein IF 1 . Here, we used homologous recombination to delete the ζ subunit from the P. denitrificans genome, and compared ATP synthesis and hydrolysis by the wild-type and knockout enzymes in inverted membrane vesicles and the F 1 -ATPase subcomplex. ATP synthesis was not affected by loss of the ζ subunit, and the rate of ATP hydrolysis increased by less than twofold, remaining negligible in comparison with the rates of the Escherichia coli and mammalian enzymes. Therefore, deleting the P. denitrificans ζ subunit is not sufficient to activate ATP hydrolysis. We close by considering our conclusions in the light of reversible catalysis and regulation in ATP synthase enzymes.

scholarly journals Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of the natural ATPase inhibitor protein.

1983 ◽  
Vol 258 (22) ◽  
pp. 13680-13684 ◽  
Author(s):  
M T Tuena de Gómez-Puyou ◽  
U Muller ◽  
G Dreyfus ◽  
G Ayala ◽  
A Gómez-Puyou
Keyword(s):  
Mitochondrial Atpase ◽  
Inhibitor Protein ◽  
Atpase Inhibitor ◽  
Hydrolysis Of

scholarly journals A Theoretical Model of Mitochondrial ATP Synthase Deficiencies. The Role of Mitochondrial Carriers

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1424
Author(s):  
Jean-Pierre Mazat ◽  
Anne Devin ◽  
Edgar Yoboue ◽  
Stéphane Ransac
Keyword(s):  
Atp Synthase ◽  
Point Mutations ◽  
Atp Synthesis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Complex Iv ◽  
Equivalent Point ◽  
Mitochondrial Atp Synthase ◽  
Atp6 Gene ◽  
Substrate Level

The m.8993T>G mutation of the mitochondrial MT-ATP6 gene is associated with NARP syndrome (neuropathy, ataxia and retinitis pigmentosa). The equivalent point mutation introduced in yeast Saccharomyces cerevisiae mitochondrial DNA considerably reduced the activity of ATP synthase and of cytochrome-c-oxidase, preventing yeast growth on oxidative substrates. The overexpression of the mitochondrial oxodicarboxylate carrier (Odc1p) was able to rescue the growth on the oxidative substrate by increasing the substrate-level phosphorylation of ADP coupled to the conversion of α-ketoglutarate (AKG) into succinate with an increase in Complex IV activity. Previous studies showed that equivalent point mutations in ATP synthase behave similarly and can be rescued by Odc1p overexpression and/or the uncoupling of OXPHOS from ATP synthesis. In order to better understand the mechanism of the ATP synthase mutation bypass, we developed a core model of mitochondrial metabolism based on AKG as a respiratory substrate. We describe the different possible metabolite outputs and the ATP/O ratio values as a function of ATP synthase inhibition.

Downmodulation of mitochondrial F0F1ATP synthase by diazoxide in cardiac myoblasts: a dual effect of the drug

2007 ◽  
Vol 292 (2) ◽  
pp. H820-H829 ◽  
Author(s):  
Marina Comelli ◽  
Giuliana Metelli ◽  
Irene Mavelli
Keyword(s):  
Atpase Activity ◽  
Atp Synthase ◽  
Transmembrane Potential ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Mitochondrial Transmembrane Potential ◽  
Mitochondrial Atpase ◽  
Inhibitor Protein ◽  
Atp Content ◽  
Intact Cells

Similar to ischemic preconditioning, diazoxide was documented to elicit beneficial bioenergetic consequences linked to cardioprotection. Inhibition of ATPase activity of mitochondrial F0F1ATP synthase may have a role in such effect and may involve the natural inhibitor protein IF1. We recently documented, using purified enzyme and isolated mitochondrial membranes from beef heart, that diazoxide interacts with the F1sector of F0F1ATP synthase by promoting IF1binding and reversibly inhibiting ATP hydrolysis. Here we investigated the effects of diazoxide on the enzyme in cultured myoblasts. Specifically, embryonic heart-derived H9c2 cells were exposed to diazoxide and mitochondrial ATPase was assayed in conditions maintaining steady-state IF1binding (basal ATPase activity) or detaching bound IF1at alkaline pH. Mitochondrial transmembrane potential and uncoupling were also investigated, as well as ATP synthesis flux and ATP content. Diazoxide at a cardioprotective concentration (40 μM cell-associated concentration) transiently downmodulated basal ATPase activity, concomitant with mild mitochondria uncoupling and depolarization, without affecting ATP synthesis and ATP content. Alkaline stripping of IF1from F0F1ATP synthase was less in diazoxide-treated than in untreated cells. Pretreatment with glibenclamide prevented, together with mitochondria depolarization, inhibition of ATPase activity under basal but not under IF1-stripping conditions, indicating that diazoxide alters alkaline IF1release. Diazoxide inhibition of ATPase activity in IF1-stripping conditions was observed even when mitochondrial transmembrane potential was reduced by FCCP. The results suggest that diazoxide in a model of normoxic intact cells directly promotes binding of inhibitor protein IF1to F0F1ATP synthase and enhances IF1binding indirectly by mildly uncoupling and depolarizing mitochondria.

The F1Fo-ATPase inhibitor, IF1, is a critical regulator of energy metabolism in cancer cells

2021 ◽  
Vol 49 (2) ◽  
pp. 815-827
Author(s):  
Giancarlo Solaini ◽  
Gianluca Sgarbi ◽  
Alessandra Baracca
Keyword(s):  
Cancer Cells ◽  
Atp Synthase ◽  
Aerobic Glycolysis ◽  
Cell Metabolism ◽  
Metabolic Reprogramming ◽  
Endogenous Inhibitor ◽  
Atpase Inhibitor ◽  
Molecular Action ◽  
F1fo Atpase

In the last two decades, IF1, the endogenous inhibitor of the mitochondrial F1Fo-ATPase (ATP synthase) has assumed greater and ever greater interest since it has been found to be overexpressed in many cancers. At present, several findings indicate that IF1 is capable of playing a central role in cancer cells by promoting metabolic reprogramming, proliferation and resistance to cell death. However, the mechanism(s) at the basis of this pro-oncogenic action of IF1 remains elusive. Here, we recall the main features of the mechanism of the action of IF1 when the ATP synthase works in reverse, and discuss the experimental evidence that support its relevance in cancer cells. In particular, a clear pro-oncogenic action of IF1 is to avoid wasting of ATP when cancer cells are exposed to anoxia or near anoxia conditions, therefore favoring cell survival and tumor growth. However, more recently, various papers have described IF1 as an inhibitor of the ATP synthase when it is working physiologically (i.e. synthethizing ATP), and therefore reprogramming cell metabolism to aerobic glycolysis. In contrast, other studies excluded IF1 as an inhibitor of ATP synthase under normoxia, providing the basis for a hot debate. This review focuses on the role of IF1 as a modulator of the ATP synthase in normoxic cancer cells with the awareness that the knowledge of the molecular action of IF1 on the ATP synthase is crucial in unravelling the molecular mechanism(s) responsible for the pro-oncogenic role of IF1 in cancer and in developing related anticancer strategies.

scholarly journals The role of bound potassium ions in the hydrolysis of low concentrations of adenosine triphosphate by preparations of membrane fragments from ox brain cerebral cortex

1970 ◽  
Vol 120 (1) ◽  
pp. 15-24 ◽  
Author(s):  
P. S. G. Goldfarb ◽  
R. Rodnight
Keyword(s):  
Potassium Chloride ◽  
Magnesium Chloride ◽  
Adenosine Triphosphatase ◽  
Time Course ◽  
Atp Hydrolysis ◽  
Protein Ratio ◽  
Low Concentrations ◽  
Hydrolysis Of ◽  
Emission Flame

1. The intrinsic Na+, K+, Mg2+ and Ca2+ contents of a preparation of membrane fragments from ox brain were determined by emission flame photometry. 2. Centrifugal washing of the preparation with imidazole-buffered EDTA solutions decreased the bound Na+ from 90±20 to 24±12, the bound K+ from 27±3 to 7±2, the bound Mg2+ from 20±2 to 3±1 and the bound calcium from 8±1 to <1nmol/mg of protein. 3. The activities of the Na++K++Mg2+-stimulated adenosine triphosphatase and the Na+-dependent reaction forming bound phosphate were compared in the unwashed and washed preparations at an ATP concentration of 2.5μm (ATP/protein ratio 12.5pmol/μg). 4. The Na+-dependent hydrolysis of ATP as well as the plateau concentration of bound phosphate and the rate of dephosphorylation were decreased in the washed preparation. The time-course of formation and decline of bound phosphate was fully restored by the addition of 2.5μm-magnesium chloride and 2μm-potassium chloride. Addition of 2.5μm-magnesium chloride alone fully restored the plateau concentration of bound phosphate, but the rate of dephosphorylation was only slightly increased. Na+-dependent ATP hydrolysis was partly restored with 2.5μm-magnesium chloride; addition of K+ in the range 2–10μm-potassium chloride then further restored hydrolysis but not to the control rate. 5. Pretreatment of the washed preparation at 0°C with 0.5nmol of K+/mg of protein so that the final added K+ in the reaction mixture was 0.1μm restored the Na+-dependent hydrolysis of ATP and the time-course of the reaction forming bound phosphate. 6. The binding of [42K]potassium chloride by the washed membrane preparation was examined. Binding in a solution containing 10nmol of K+/mg of protein was linear over a period of 20min and was inhibited by Na+. Half-maximal inhibition of 42K+-binding required a 100-fold excess of sodium chloride. 7. It was concluded (a) that a significant fraction of the apparent Na+-dependent hydrolysis of ATP observed in the unwashed preparation is due to activation by bound K+ and Mg2+ of the Na++K++Mg2+-stimulated adenosine triphosphatase system and (b) that the enzyme system is able to bind K+ from a solution of 0.5μm-potassium chloride.

scholarly journals Aerobic Growth of Escherichia coli Is Reduced, and ATP Synthesis Is Selectively Inhibited when Five C-terminal Residues Are Deleted from the ϵ Subunit of ATP Synthase

2015 ◽  
Vol 290 (34) ◽  
pp. 21032-21041 ◽  
Author(s):  
Naman B. Shah ◽  
Thomas M. Duncan
Keyword(s):  
Escherichia Coli ◽  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Intrinsic Rate ◽  
Synthesis Rate ◽  
Final Segment ◽  
Rotary Catalysis

F-type ATP synthases are rotary nanomotor enzymes involved in cellular energy metabolism in eukaryotes and eubacteria. The ATP synthase from Gram-positive and -negative model bacteria can be autoinhibited by the C-terminal domain of its ϵ subunit (ϵCTD), but the importance of ϵ inhibition in vivo is unclear. Functional rotation is thought to be blocked by insertion of the latter half of the ϵCTD into the central cavity of the catalytic complex (F1). In the inhibited state of the Escherichia coli enzyme, the final segment of ϵCTD is deeply buried but has few specific interactions with other subunits. This region of the ϵCTD is variable or absent in other bacteria that exhibit strong ϵ-inhibition in vitro. Here, genetically deleting the last five residues of the ϵCTD (ϵΔ5) caused a greater defect in respiratory growth than did the complete absence of the ϵCTD. Isolated membranes with ϵΔ5 generated proton-motive force by respiration as effectively as with wild-type ϵ but showed a nearly 3-fold decrease in ATP synthesis rate. In contrast, the ϵΔ5 truncation did not change the intrinsic rate of ATP hydrolysis with membranes. Further, the ϵΔ5 subunit retained high affinity for isolated F1 but reduced the maximal inhibition of F1-ATPase by ϵ from >90% to ∼20%. The results suggest that the ϵCTD has distinct regulatory interactions with F1 when rotary catalysis operates in opposite directions for the hydrolysis or synthesis of ATP.

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