Free fatty acids regulate the uncoupling protein and alternative oxidase activities in plant mitochondria

Sluse, Francis; Almeida, Aparecida Marques de; Jarmuszkiewicz, Wiesława; Vercesi, Anı́bal E.

doi:10.1016/s0014-5793(98)00922-3

Cited by 78 publications

(65 citation statements)

References 21 publications

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“…They also show that AOX and PUMP never seem to work simultaneously at least at their maximal activity, and it is likely that when PUMP reaches high activity AOX is already fully switched off (16). addition of KCN and terminated by BHAM.…”

Section: Aox and Pump Activity During Tomato Fruit Post-harvest Ripeningmentioning

confidence: 98%

“…Since the common final effect of the AOX and PUMP activities is a decrease in ATP synthesis efficiency, it can be quantified by ADP/O ratio measurements (16 ADP/O is measured during an ADP pulse (0.17 mM) with succinate (10 mM) plus rotenone as oxidizable substrate. O is the total amount of oxygen consumed during state 3 respiration.…”

Section: Aox-pump Connectionmentioning

confidence: 99%

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Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

Sluse

Jarmuszkiewicz

2000

Braz J Med Biol Res

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Cyanide-resistant alternative oxidase (AOX) is not limited to plant mitochondria and is widespread among several types of protists. The uncoupling protein (UCP) is much more widespread than previously believed, not only in tissues of higher animals but also in plants and in an amoeboid protozoan. The redox energy-dissipating pathway (AOX) and the proton electrochemical gradient energy-dissipating pathway (UCP) lead to the same final effect, i.e., a decrease in ATP synthesis and an increase in heat production. Studies with green tomato fruit mitochondria show that both proteins are present simultaneously in the membrane. This raises the question of a specific physiological role for each energy-dissipating system and of a possible functional connection between them (shared regulation). Linoleic acid, an abundant free fatty acid in plants which activates UCP, strongly inhibits cyanide-resistant respiration mediated by AOX. Moreover, studies of the evolution of AOX and UCP protein expression and of their activities during post-harvest ripening of tomato fruit show that AOX and plant UCP work sequentially: AOX activity decreases in early post-growing stages and UCP activity is decreased in late ripening stages. Electron partitioning between the alternative oxidase and the cytochrome pathway as well as H + gradient partitioning between ATP synthase and UCP can be evaluated by the ADP/O method. This method facilitates description of the kinetics of energy-dissipating pathways and of ATP synthase when state 3 respiration is decreased by limitation of oxidizable substrate.

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Section: Aox and Pump Activity During Tomato Fruit Post-harvest Ripeningmentioning

confidence: 98%

Section: Aox-pump Connectionmentioning

confidence: 99%

Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

Sluse

Jarmuszkiewicz

2000

Braz J Med Biol Res

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“…brown adipose tissue), where they act as uncouplers of the mitochondrial electron transport chain, allowing energy derived from lipids to be used for heat generation instead of ATP production (Knutson, 1974;Klingenberg and Winkler, 1985). Furthermore, a number of studies have reported that the AOX and UCP co-occur in plant tissues (Sluse et al, 1998;Considine et al, 2001;Ito and Seymour, 2005). UCP may short-circuit protons that could be transferred before the AOX, accounting for the complete conversion of energy entering the electron transport chain to heat with no ATP production (Seymour et al, 1983;Lamprecht et al, 1998).…”

mentioning

confidence: 99%

“…Although UCP is equally expressed in both thermogenic and nonthermogenic tissues in dead-horse arum (Helicodiceros muscivorus; Ito et al, 2003), it may have a thermogenic function in mitochondria with high AOX activity. However, the free fatty acids that stimulate UCP activity appear to inhibit the AOX, thus it is unlikely that both will reach maximal activity simultaneously (Sluse et al, 1998). The involvement of AOX and UCP appears to depend on the substrate catabolized.…”

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confidence: 99%

Contribution of the Alternative Pathway to Respiration during Thermogenesis in Flowers of the Sacred Lotus

2006

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We report results from in vivo measurements, using oxygen isotope discrimination techniques, of fluxes through the alternative and cytochrome respiratory pathways in thermogenic plant tissue, the floral receptacle of the sacred lotus (Nelumbo nucifera). Fluxes through both pathways were measured in thermoregulating flowers undergoing varying degrees of thermogenesis in response to ambient temperature. Significant increases in alternative pathway flux were found in lotus receptacles with temperatures 16°C to 20°C above ambient, but not in those with lesser amounts of heating. Alternative pathway flux in the hottest receptacles was 75% of the total respiratory flux. In contrast, fluxes through the cytochrome pathway did not change significantly during thermogenesis. These data support the hypothesis that increased flux through the alternative pathway is responsible for heating in the lotus and that it is unlikely that uncoupling proteins, which would have produced increased fluxes through the cytochrome pathway, contribute significantly to heating in this tissue. Comparisons of actual flux, with capacity determined using inhibitors, suggested that the alternative pathway was operating at close to maximum capacity in heating tissues of lotus. However, in nonheating tissues the inhibitor data significantly overestimated the alternative pathway flux. This confirms that isotopic measurements are necessary for accurate determination of fluxes through the two pathways.

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“…The presence of two dissipative pathways in plants is curious, and raises questions regarding the regulation of these pathways. Although the contribution of each pathway under different conditions of plant thermogenesis has not been well established, it now seems clear that these pathways do not operate simultaneously (15).…”

Section: Thermogenesismentioning

confidence: 99%

Alternative mitochondrial functions in cell physiopathology: beyond ATP production

2000

Braz J Med Biol Res

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It is well known that mitochondria are the main site for ATP generation within most tissues. However, mitochondria also participate in a surprising number of alternative activities, including intracellular Ca 2+ regulation, thermogenesis and the control of apoptosis. In addition, mitochondria are the main cellular generators of reactive oxygen species, and may trigger necrotic cell death under conditions of oxidative stress. This review

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Free fatty acids regulate the uncoupling protein and alternative oxidase activities in plant mitochondria

Cited by 78 publications

References 21 publications

Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit

Contribution of the Alternative Pathway to Respiration during Thermogenesis in Flowers of the Sacred Lotus

Alternative mitochondrial functions in cell physiopathology: beyond ATP production

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