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See detailRedox state of endogenous coenzyme q modulates the inhibition of linoleic acid-induced uncoupling by guanosine triphosphate in isolated skeletal muscle mitochondria.
Jarmuszkiewicz, W.; Navet, R.; Alberici, L. et al

in Journal of Bioenergetics & Biomembranes (2004), 36

The skeletal muscle mitochondria contain two isoforms of uncoupling protein, UCP2 and mainly UCP3, which had been shown to be activated by free fatty acids and inhibited by purine nucleotides in ... [more ▼]

The skeletal muscle mitochondria contain two isoforms of uncoupling protein, UCP2 and mainly UCP3, which had been shown to be activated by free fatty acids and inhibited by purine nucleotides in reconstituted systems. On the contrary in isolated mitochondria, the protonophoretic action of muscle UCPs had failed to be demonstrated in the absence of superoxide production. We showed here for the first time that muscle UCPs were activated in state 3 respiration by linoleic acid and dissipated energy from oxidative phosphorylation by decreasing the ADP/O ratio. The efficiency of UCPs in mitochondrial uncoupling increased when the state 3 respiratory rate decreased. The inhibition of the linoleic acid-induced uncoupling by a purine nucleotide (GTP), was not observed in state 4 respiration, in uninhibited state 3 respiration, as well as in state 3 respiration inhibited by complex III inhibitors. On the contrary, the progressive inhibition of state 3 respiration by n -butyl malonate, which inhibits the uptake of succinate, led to a full inhibitory effect of GTP. Therefore, as the inhibitory effect of GTP was observed only when the reduced state of coenzyme Q was decreased, we propose that the coenzyme Q redox state could be a metabolic sensor that modulates the purine nucleotide inhibition of FFA-activated UCPs in muscle mitochondria. [less ▲]

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See detailThe energy-conserving and energy-dissipating processes in mitochondria isolated from wild type and nonripening tomato fruits during development on the plant.
Almeida, A.; Navet, R.; Jarmuszkiewicz, W. et al

in Journal of Bioenergetics & Biomembranes (2002), 34(6), 487-498

Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, non-climacteric ... [more ▼]

Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, non-climacteric) fruits. Fruit development was expressed in terms of evolution of chlorophyll a content allowing the assessment of a continuous time-course in both cultivars. Measured parameters: the cytochrome pathway-dependent respiration, i.e., the ATP synthesis-sustained respiration (energy-conserving), the uncoupling protein (UCP) activity-sustained respiration (energy-dissipating), the alternative oxidase(AOX)-mediated respiration (energy-dissipating), as well as the protein expression of UCP and AOX, and free fatty acid content exhibited different evolution patterns in the wild type and nor mutant that can be attributed to their climacteric/nonclimacteric properties, respectively. In the wild type, the climacteric respiratory burst observed in vitro depended totally on an increse in the cytochrome pathway activity sustained by ATP synthesis, while the second respiratory rise during the ripening stage was linked to a strong increase in AOX activity accompanied by an overexpression of AOX protein. In wild type mitochondria, the 10-microM linoleic acid-stimulated UCP-activity-dependent respiration remained constant during the whole fruit development except in senescence where general respiratory decay was observed. [less ▲]

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See detailAlternative oxidase and uncoupling protein: thermogenesis versus cell energy balance.
Jarmuszkiewicz, W.; Sluse-Goffart, C.; Vercesi, A. et al

in Bioscience Reports (2001), 21(2), 213-222

The physiological role of an alternative oxidase and an uncoupling protein in plant and protists is discussed in terms of thermogenesis and energy metabolism balance in the cell. It is concluded that ... [more ▼]

The physiological role of an alternative oxidase and an uncoupling protein in plant and protists is discussed in terms of thermogenesis and energy metabolism balance in the cell. It is concluded that thermogenesis is restricted not only by a lower-limit size but also by a kinetically-limited stimulation of the mitochondrial respiratory chain. [less ▲]

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See detailRespiratory chain network in mitochondria of Candida parapsilosis: ADP/O appraisal of the multiple electron pathways.
Milani, G.; Jarmuszkiewicz, W.; Sluse-Goffart, C. et al

in FEBS Letters (2001), 508

In this study we demonstrated that mitochondria of Candida parapsilosis contain a constitutive ubiquinol alternative oxidase (AOX) in addition to a classical respiratory chain (CRC) and a parallel ... [more ▼]

In this study we demonstrated that mitochondria of Candida parapsilosis contain a constitutive ubiquinol alternative oxidase (AOX) in addition to a classical respiratory chain (CRC) and a parallel respiratory chain (PAR) both terminating by two different cytochrome c oxidases. The C. parapsilosis AOX is characterized by a fungi-type regulation by GMP (as a stimulator) and linoleic acid (as an inhibitor). Inhibitor screening of the respiratory network by the ADP/O ratio and state 3 respiration determinations showed that (i) oxygen can be reduced by the three terminal oxidases through four paths implying one bypass between CRC and PAR and (ii) the sum of CRC, AOX and PAR capacities is higher than the overall respiration (no additivity) and that their engagement could be progressive according to the redox state of ubiquinone, i.e. first cytochrome pathway, then AOX and finally PAR. [less ▲]

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See detailProton partitioning between ATP synthase and uncoupling protein during cytochrome pathway state 3 respiration in tomato fruit mitochondria
Sluse, Francis ULg; Jarmuszkiewicz, W.; Almeida, A. M. et al

in Hofmeyr, J.; Rohwer, J. M.; Snoops, J. L. (Eds.) Biothermokinetic 2000 : Animating the cellular map (2000)

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See detailProton re-uptake partitioning between uncoupling protein and ATP synthase during benzohydroxamic acid-resistant state 3 respiration in tomato fruit mitochondria.
Jarmuszkiewicz, W.; Almeida, A.; Vercesi, A. et al

in Journal of Biological Chemistry (2000), 275(18), 13315-13320

The yield of oxidative phosphorylation in isolated tomato fruit mitochondria depleted of free fatty acids remains constant when respiratory rates are decreased by a factor of 3 by the addition of n-butyl ... [more ▼]

The yield of oxidative phosphorylation in isolated tomato fruit mitochondria depleted of free fatty acids remains constant when respiratory rates are decreased by a factor of 3 by the addition of n-butyl malonate. This constancy makes the determination of the contribution of the linoleic acid-induced energy-dissipating pathway by the ADP/O method possible. No decrease in membrane potential is observed in state 3 respiration with increasing concentration of n-butyl malonate, indicating that the rate of ATP synthesis is steeply dependent on membrane potential. Linoleic acid decreases the yield of oxidative phosphorylation in a concentration-dependent manner by a pure protonophoric process like that in the presence of FCCP. ADP/O measurements allow calculation of the part of respiration leading to ATP synthesis and the part of respiration sustained by the dissipative H(+) re-uptake induced by linoleic acid. Respiration sustained by this energy-dissipating process remains constant at a given LA concentration until more than 50% inhibition of state 3 respiration by n-butyl malonate is achieved. The energy dissipative contribution to oxygen consumption is proposed to be equal to the protonophoric activity of plant uncoupling protein divided by the intrinsic H(+)/O of the cytochrome pathway. It increases with linoleic acid concentration, taking place at the expense of ADP phosphorylation without an increase in the respiration. [less ▲]

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See detailIdentification and characterization of a protozoan uncoupling protein in Acanthamoeba castellanii.
Jarmuszkiwicz, W.; Milani, G.; Fortes, F. et al

in FEBS Letters (2000), 467

An uncoupling protein (UCP) was identified in mitochondria from Candida parapsilosis (CpUCP), a non-fermentative parasitic yeast. CpUCP was immunodetected using polyclonal antibodies raised against plant ... [more ▼]

An uncoupling protein (UCP) was identified in mitochondria from Candida parapsilosis (CpUCP), a non-fermentative parasitic yeast. CpUCP was immunodetected using polyclonal antibodies raised against plant UCP. Activity of CpUCP, investigated in mitochondria depleted of free fatty acids, was stimulated by linoleic acid (LA) and inhibited by GTP. Activity of CpUCP enhanced state 4 respiration by decreasing DeltaPsi and lowered the ADP/O ratio. Thus, it was able to divert energy from oxidative phosphorylation. The voltage dependence of electron flux indicated that LA had a pure protonophoretic effect. The discovery of CpUCP proves that UCP-like proteins occur in the four eukaryotic kingdoms: animals, plants, fungi and protists. [less ▲]

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See detailCyanide-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration during postharvest ripening of tomato fruit
Almeida, A.; Jarmuszkiewicz, W.; Khomsi, H. et al

in Plant Physiology (1999), 119

Tomato (Lycopersicon esculentum) mitochondria contain both alternative oxidase (AOX) and uncoupling protein as energy-dissipating systems that can decrease the efficiency of oxidative phosphorylation. We ... [more ▼]

Tomato (Lycopersicon esculentum) mitochondria contain both alternative oxidase (AOX) and uncoupling protein as energy-dissipating systems that can decrease the efficiency of oxidative phosphorylation. We followed the cyanide (CN)-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration of isolated mitochondria, as well as the immunologically detectable levels of uncoupling protein and AOX, during tomato fruit ripening from the mature green stage to the red stage. The AOX protein level and CN-resistant respiration of isolated mitochondria decreased with ripening from the green to the red stage. The ATP-synthesis-sustained respiration followed the same behavior. In contrast, the level of uncoupling protein and the total uncoupling-protein-sustained respiration of isolated mitochondria decreased from only the yellow stage on. We observed an acute inhibition of the CN-resistant respiration by linoleic acid in the micromolar range. These results suggest that the two energy-dissipating systems could have different roles during the ripening process. [less ▲]

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See detailDetermination of the respective contributions of energy-dissipating athways to mitochondrial respiration : The ADP/O method
Sluse, Francis ULg; Jarmuszkiewicz, W.; Almeida, A. et al

in Moller, I. M.; Gardestrom, P.; Glimelius, K. (Eds.) et al Plant mitochondria : from gene to function (1998)

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See detailLinoleic acid-induced activity of plant uncoupling mitochondrial protein in purified tomato fruit mitochondria during resting, phosphorylating, and progressively uncoupled respiration.
Jarmuszkiewicz, W.; Almeida, A.; Sluse-goffart, C. et al

in Journal of Biological Chemistry (1998), 273(52), 34882-34886

An uncoupling protein was recently discovered in plant mitochondria and demonstrated to function similarly to the uncoupling protein of brown adipose tissue. In this work, green tomato fruit mitochondria ... [more ▼]

An uncoupling protein was recently discovered in plant mitochondria and demonstrated to function similarly to the uncoupling protein of brown adipose tissue. In this work, green tomato fruit mitochondria were purified on a self-generating Percoll gradient in the presence of 0.5% bovine serum albumin to deplete mitochondria of endogenous free fatty acids. The uncoupling protein activity was induced by the addition of linoleic acid during the resting state, and in the progressively uncoupled state, as well as during phosphorylating respiration in the presence of benzohydroxamic acid, an inhibitor of the alternative oxidase and with succinate (+ rotenone) as oxidizable substrate. Linoleic acid strongly stimulated the resting respiration in fatty acid-depleted mitochondria but had no effect on phosphorylating respiration, suggesting no activity of the uncoupling protein in this respiratory state. Progressive uncoupling of state 4 respiration decreased the stimulation by linoleic acid. The similar respiratory rates in phosphorylating and fully uncoupled respiration in the presence and absence of linoleic acid suggested that a rate-limiting step on the dehydrogenase side of the respiratory chain was responsible for the insensitivity of phosphorylating respiration to linoleic acid. Indeed, the ADP/O ratio determined by ADP/O pulse method was decreased by linoleic acid, indicating that uncoupling protein was active during phosphorylating respiration and was able to divert energy from oxidative phosphorylation. Moreover, the respiration rates appeared to be determined by membrane potential independently of the presence of linoleic acid, indicating that linoleic acid-induced stimulation of respiration is due to a pure protonophoric activity without any direct effect on the electron transport chain. [less ▲]

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