Redox state of quinone affects sensitivity of Acanthamoeba castellanii mitochondrial uncoupling protein to purine nucleotides

2008 ◽  
Vol 413 (2) ◽  
pp. 359-367 ◽  
Author(s):  
Aleksandra Swida ◽  
Andrzej Woyda-Ploszczyca ◽  
Wieslawa Jarmuszkiewicz
Keyword(s):  
Respiratory Rate ◽  
Redox State ◽  
Uncoupling Protein ◽  
Acanthamoeba Castellanii ◽  
Inhibitory Effect ◽  
Proton Conductance ◽  
Purine Nucleotides ◽  
Protein Activity ◽  
Mitochondrial Uncoupling ◽  
Quinone Reduction

We studied FFA (free fatty acid)-induced uncoupling activity in Acanthamoeba castellanii mitochondria in the non-phosphorylating state. Either succinate or external NADH was used as a respiratory substrate to determine the proton conductance curves and the relationships between respiratory rate and the quinone reduction level. Our determinations of the membranous quinone reduction level in non-phosphorylating mitochondria show that activation of UCP (uncoupling protein) activity leads to a PN (purine nucleotide)-sensitive decrease in the quinone redox state. The gradual decrease in the rate of quinone-reducing pathways (using titration of dehydrogenase activities) progressively leads to a full inhibitory effect of GDP on LA (linoleic acid) induced proton conductance. This inhibition cannot be attributed to changes in the membrane potential. Indeed, the lack of GDP inhibitory effect observed when the decrease in respiratory rate is accompanied by an increase in the quinone reduction level (using titration of the quinol-oxidizing pathway) proves that the inhibition by nucleotides can be revealed only for a low quinone redox state. It must be underlined that, in A. castellanii non-phosphorylating mitochondria, the transition of the inhibitory effect of GDP on LA-induced UCP-mediated uncoupling is observed for the same range of quinone reduction levels (between 50% and 40%) as that observed previously for phosphorylating conditions. This observation, drawn from the two different metabolic states of mitochondria, indicates that quinone could affect UCP activity through sensitivity to PNs.

Hydroxynonenal-stimulated activity of the uncoupling protein in Acanthamoeba castellanii mitochondria under phosphorylating conditions

2013 ◽  
Vol 394 (5) ◽  
pp. 649-658 ◽  
Author(s):  
Andrzej Woyda-Ploszczyca ◽  
Wieslawa Jarmuszkiewicz
Keyword(s):  
Respiratory Rate ◽  
Atp Synthase ◽  
Redox State ◽  
Uncoupling Protein ◽  
Acanthamoeba Castellanii ◽  
Complex Iii ◽  
Dependent Manner ◽  
Mitochondrial Uncoupling ◽  
Concentration Dependent Manner ◽  
Succinate Oxidation

Abstract The influence of 4-hydroxy-2-nonenal (HNE), a lipid peroxidation end product, on the activity of the amoeba Acanthamoeba castellanii uncoupling protein (AcUCP) in isolated phosphorylating mitochondria was studied. Under phosphorylating conditions, exogenously added HNE induced GTP-sensitive AcUCP-mediated mitochondrial uncoupling. The HNE-induced proton leak decreased the yield of oxidative phosphorylation in an HNE concentration-dependent manner. The present study describes how the contributions of ATP synthase and HNE-induced AcUCP in phosphorylating respiration vary when the rate of succinate oxidation is decreased by limiting succinate uptake or inhibiting complex III activity within the range of a constant membrane potential. In phosphorylating mitochondria, at a given HNE concentration (100 μm), the efficiency of AcUCP in mitochondrial uncoupling increased as the respiratory rate decreased because the AcUCP contribution remained constant while the ATP synthase contribution decreased with the respiratory rate. HNE-induced uncoupling can be inhibited by GTP only when ubiquinone is sufficiently oxidized, indicating that in phosphorylating A. castellanii mitochondria, the sensitivity of AcUCP activity to GTP depends on the redox state of the membranous ubiquinone.

In Phosphorylating Acanthamoeba castellanii Mitochondria the Sensitivity of Uncoupling Protein Activity to GTP Depends on the Redox State of Quinone

2005 ◽  
Vol 37 (2) ◽  
pp. 97-107 ◽  
Author(s):  
Wieslawa Jarmuszkiewicz ◽  
Aleksandra Swida ◽  
Malgorzata Czarna ◽  
Nina Antos ◽  
Claudine M. Sluse-Goffart ◽  
...  
Keyword(s):  
Redox State ◽  
Uncoupling Protein ◽  
Acanthamoeba Castellanii ◽  
Protein Activity

scholarly journals The contribution of uncoupling protein and ATP synthase to state 3 respiration in Acanthamoeba castellanii mitochondria.

2004 ◽  
Vol 51 (2) ◽  
pp. 533-538 ◽  
Author(s):  
Wiesława Jarmuszkiewicz ◽  
Małgorzata Czarna ◽  
Claudine Sluse-Goffart ◽  
Francis E Sluse
Keyword(s):  
Fatty Acid ◽  
Linoleic Acid ◽  
Free Fatty Acid ◽  
Respiratory Rate ◽  
Atp Synthase ◽  
Acid Concentration ◽  
Uncoupling Protein ◽  
Acanthamoeba Castellanii ◽  
Mitochondrial Uncoupling ◽  
Linoleic Acid Concentration

Mitochondria of the amoeba Acanthamoeba castellanii possess a free fatty acid-activated uncoupling protein (AcUCP) that mediates proton re-uptake driven by the mitochondrial proton electrochemical gradient. We show that AcUCP activity diverts energy from ATP synthesis during state 3 mitochondrial respiration in a fatty acid-dependent way. The efficiency of AcUCP in mitochondrial uncoupling increases when the state 3 respiratory rate decreases as the AcUCP contribution is constant at a given linoleic acid concentration while the ATP synthase contribution decreases with respiratory rate. Respiration sustained by this energy-dissipating process remains constant at a given linoleic acid concentration until more than 60% inhibition of state 3 respiration by n-butyl malonate is achieved. The present study supports the validity of the ADP/O method to determine the actual contributions of AcUCP (activated with various linoleic acid concentrations) and ATP synthase in state 3 respiration of A.castellanii mitochondria fully depleted of free fatty acid-activated and describes how the two contributions vary when the rate of succinate dehydrogenase is decreased by succinate uptake limitation.

scholarly journals Structural models of mitochondrial uncoupling proteins obtained in DPC micelles are not physiologically relevant for their uncoupling activity

2020 ◽  
Author(s):  
Mathilde S. Piel ◽  
Sandrine Masscheleyn ◽  
Frédéric Bouillaud ◽  
Karine Moncoq ◽  
Bruno Miroux
Keyword(s):  
Uncoupling Protein ◽  
Brown Adipocyte ◽  
Acid Oxidation ◽  
Long Chain Fatty Acids ◽  
Proton Conductance ◽  
Uncoupling Protein 1 ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Uncoupling Proteins

AbstractUncoupling protein 1 (UCP1) is found in the inner mitochondrial membrane of brown adipocyte. In the presence of long-chain fatty acids (LCFA), UCP1 increases the proton conductance, which, in turn, increases fatty acid oxidation and energy release as heat. Several atomic models of UCP1 and UCP2 have been obtained by NMR in dodecylphosphocholine (DPC), a detergent known to inactivate UCP1. Based on NMR titration experiment on UCP1 with LCFA, it has been proposed that K56 and K269 are crucial for LCFA binding and UCP1 activation. Given the numerous controversies on the use of DPC for structure-function analyses of membrane proteins, we revisited those UCP1 mutants in a more physiological context by expressing them in the mitochondria of S. cerevisiae. Mitochondrial respiration, assayed on permeabilized spheroplasts, enables the determination of UCP1 activation and inhibition. The K56S, K269S and K56S/K269S mutants did not display any default in activation, which shows that the NMR experiments in DPC detergent are not relevant to understand UCP1 function.

scholarly journals Uncoupling proteins in mitochondria of plants and some microorganisms.

2001 ◽  
Vol 48 (1) ◽  
pp. 145-155 ◽  
Author(s):  
W Jarmuszkiewicz
Keyword(s):  
Higher Plants ◽  
Uncoupling Protein ◽  
Physiological Role ◽  
Acanthamoeba Castellanii ◽  
Uncoupling Proteins ◽  
Protein Activity ◽  
Functional Connection ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Carrier Family

Uncoupling proteins, members of the mitochondrial carrier family, are present in mitochondrial inner membrane and mediate free fatty acid-activated, purine-nucleotide-inhibited H+ re-uptake. Since 1995, it has been shown that the uncoupling protein is present in many higher plants and some microorganisms like non-photosynthetic amoeboid protozoon, Acanthamoeba castellanii and non-fermentative yeast Candida parapsilosis. In mitochondria of these organisms, uncoupling protein activity is revealed not only by stimulation of state 4 respiration by free fatty acids accompanied by decrease in membrane potential (these effects being partially released by ATP and GTP) but mainly by lowering ADP/O ratio during state 3 respiration. Plant and microorganism uncoupling proteins are able to divert very efficiently energy from oxidative phosphorylation, competing for deltamicroH+ with ATP synthase. Functional connection and physiological role of uncoupling protein and alternative oxidase, two main energy-dissipating systems in plant-type mitochondria, are discussed.

scholarly journals Activation and Function of Mitochondrial Uncoupling Protein in Plants

2004 ◽  
Vol 279 (50) ◽  
pp. 51944-51952 ◽  
Author(s):  
Anna M. O. Smith ◽  
R. George Ratcliffe ◽  
Lee J. Sweetlove
Keyword(s):  
Transgenic Plants ◽  
Protein Content ◽  
Uncoupling Protein ◽  
Tricarboxylic Acid Cycle ◽  
Proton Conductance ◽  
Mitochondrial Uncoupling ◽  
Experimental Conditions ◽  
Mitochondrial Uncoupling Protein ◽  
Exact Function

Plant mitochondrial uncoupling protein (UCP) is activated by superoxide suggesting that it may function to minimize mitochondrial reactive oxygen species (ROS) formation. However, the precise mechanism of superoxide activation and the exact function of UCP in plants are not known. We demonstrate that 4-hydroxy-2-nonenal (HNE), a product of lipid peroxidation, and a structurally related compound,trans-retinal, stimulate a proton conductance in potato mitochondria that is inhibitable by GTP (a characteristic of UCP). Proof that the effects of HNE andtrans-retinal are mediated by UCP is provided by examination of proton conductance in transgenic plants overexpressing UCP. These experiments demonstrate that the mechanism of activation of UCP is conserved between animals and plants and imply a conservation of function. Mitochondria from transgenic plants overexpressing UCP were further studied to provide insight into function. Experimental conditions were designed to mimic a bioenergetic state that might be foundin vivo(mitochondria were supplied with pyruvate as well as tricarboxylic cycle acids atin vivocytosolic concentrations and an exogenous ATP sink was established). Under such conditions, an increase in UCP protein content resulted in a modest but significant decrease in the rate of superoxide production. In addition,13C-labeling experiments revealed an increase in the conversion of pyruvate to citrate as a result of increased UCP protein content. These results demonstrate that under simulatedin vivoconditions, UCP is active and suggest that UCP may influence not only mitochondrial ROS production but also tricarboxylic acid cycle flux.

Coenzyme Q induces GDP-sensitive proton conductance in kidney mitochondria

2001 ◽  
Vol 29 (6) ◽  
pp. 763-768 ◽  
Author(s):  
K. S. Echtay ◽  
M. D. Brand
Keyword(s):  
Superoxide Dismutase ◽  
Fatty Acid ◽  
Coenzyme Q10 ◽  
Redox State ◽  
Uncoupling Protein ◽  
Coenzyme Q ◽  
Liver Mitochondria ◽  
Uncoupling Protein 2 ◽  
Proton Conductance ◽  
Kidney Mitochondria

Addition of coenzyme Q10 (CoQ) at low concentration (29 nmol/mg of protein) to kidney but not liver mitochondria resulted in an increase in proton conductance. This uncoupling activity required fatty acid and was completely inhibited by GDP. CoQ activated when it was likely to be reduced but not when it was likely to become oxidized. However, the redox state of endogenous CoQ did not affect mitochondrial proton conductance. Stimulation by CoQ was not inhibited by cyclosporin A, carboxyatractylate, bongkrekate and catalase but could be reversed by superoxide dismutase. We conclude that CoQ acted in mitochondria through production of superoxide, which mediated uncoupling, probably by acting through uncoupling protein 2.

Sign in / Sign up

Export Citation Format

Share Document