Phospholipid requirements for the reconstitution of complex-III vesicles exhibiting controlled electron transport

Nelson, Bruce R.; Fleischer, Sidney

doi:10.1042/bj1940783

Cited by 16 publications

(3 citation statements)

References 25 publications

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“…The above measurements were also performed with decylQH2 as electron donor yielding the same result (see also [25]). In terms of a Q-cycle, the linkage of proton and electron movement must therefore be of the same type whether DQH2 donates electrons into cytochrome reductase via centre i (see below) or decylQHz (or QH2) via centre 0.…”

Section: Proton Translocationmentioning

confidence: 54%

Dimeric ubiquinol:cytochrome c reductase of Neurospora mitochondria contains one cooperative ubiquinone‐reduction centre

Linke

Bechmann

Gothe

et al. 1986

European Journal of Biochemistry

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Dimeric ubiquinol: cytochrome c reductase of Neurospora mitochondria was isolated as a protein-Triton complex and free of ubiquinol (Q). The enzyme was incorporated into phosphatidylcholine membranes together with Q. The effects of varying the molar ratio of Q to enzyme on the electron transfer from duroquinol (DHQ,) to the cytochromes c, c1 and b were studied.The rate of electron flow from DQH2 to cytochrome c was 15 times increased by Q and was maximal when one molecule of Q was bound to one enzyme dimer. The apparent K,,, value for DQH, of the Q-free enzyme was 5 pM and of the Q-supplemented enzyme 25 pM. The pre-steady-state rate of electron transfer from DQH, to cytochrome cI was also 15 times increased by Q and was maximal with one Q molecule bound to one enzyme dimer. This effect of Q was inhibited by antimycin. The pre-steady-state rate of electron transfer from DOH, to cytochrome b was 5 times decreased when Q was bound to the enzyme and this effect of Q was insensitive to myxothiazol. The Ht/2 e-stoichiometry with DQH, as substrate of the Q-supplemented enzyme was 3.6. These results are interpreted in accordance with a Q-cycle mechanism operating in a dimeric cytochrome reductase. Each enzyme monomer catalyses a single electron transfer from the QH,-oxidation centre to the Q-reduction centre and the two monomers cooperate in the reduction of Q to QH, at one Q-reduction centre. This centre contains two different binding sites for Q. DQH, does not properly react at the QH,-oxidation centre. DQH,, however, binds to the loose Q-binding site of the Q-reduction centre and reduces the Q bound to the tight Q-binding site of the centre. The QHz thus formed at the Q-reduction centre serves as electron donor for the QH,-oxidation centre.Cytochrome reductase (ubiquinol : ferricytochrome c oxidoreductase. EC 1.10.2.2) is one of the energy-transducing electron transfer complexes of the mitochondrial system of oxidative phosphorylation. The enzyme links the transfer of electrons from QH, to cytochrome c with the translocation of protons across the mitochondrial inner membrane (for reviews see [l -31). As a mechanism for this catalysis, the protonmotive Q-cycle proposed by Mitchell [4] is now widely discussed. According to the Q-cycle, the enzyme contains two Q-catalytic centres, the QH,-oxidation centre o which is located at the outer (protonically positive) side of the enzyme and the Q-reduction centre i located at the inner (protonically negative) side (see Fig. 11 in the Discussion). Successively, two protons are released from QH2 at centre 0, one electron is transferred via the iron-sulfur centre and cytochrome c1 to cytochrome c and the other electron via the low-potential and high-potential cytochromes b across the membrane to centre i. At centre i, a bound Q is first reduced to the radical anion Q-and after transfer of a second electron to centre i and association of two protons the reduction to QH2 is completed. New support for the Q-cycle mechanism has come from recent inhibitor studies which showed that ...

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Section: Proton Translocationmentioning

confidence: 54%

Dimeric ubiquinol:cytochrome c reductase of Neurospora mitochondria contains one cooperative ubiquinone‐reduction centre

Linke

Bechmann

Gothe

et al. 1986

European Journal of Biochemistry

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“…PE molecules are bound to ETS complexes I, II, III, and IV, likely facilitating conformational changes and acting as an allosteric activator. 26-29 Indeed, enzyme activity assays revealed that activities of ETS complexes I-IV, but not V, were lower in muscles from PSD-MKO mice than in control muscles (Figure 3E). Oxidative phosphorylation is also dependent upon assembly of respiratory supercomplexes, 30,31 and PE appears to be essential for this process.…”

Section: Resultsmentioning

confidence: 95%

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

Heden

Johnson

Ferrara

et al. 2019

Preprint

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41Exercise capacity is a strong predictor of all-cause mortality. Skeletal muscle mitochondrial 42 respiratory capacity, its biggest contributor, adapts robustly to changes in energy demands 43 induced by contractile activity. While transcriptional regulation of mitochondrial enzymes has 44 been extensively studied, there is limited information on how mitochondrial membrane lipids are 45 regulated. Herein, we show that exercise training or muscle disuse alters mitochondrial 46 membrane phospholipids including phosphatidylethanolamine (PE). Addition of PE promoted, 47 whereas removal of PE diminished, mitochondrial respiratory capacity. Surprisingly, skeletal 48 muscle-specific inhibition of mitochondrial-autonomous synthesis of PE caused a respiratory 49 failure due to metabolic insults in the diaphragm muscle. While mitochondrial PE deficiency 50 coincided with increased oxidative stress, neutralization of the latter did not rescue lethality. 51 These findings highlight the previously underappreciated role of mitochondrial membrane 52 phospholipids in dynamically controlling skeletal muscle energetics and function. 53 54 55 157 3B&C), without changes in abundance of ETS enzymes (Figure 3D). PE molecules are bound to 158 ETS complexes I, II, III, and IV, likely facilitating conformational changes and acting as an 159

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“…S4F). PE molecules are bound to ETS complexes I to IV, likely facilitating conformational changes and acting as an allosteric activator ( 29 – 32 ). Enzyme activity assays revealed that activities of ETS complexes I to IV, but not V, were lower in muscles from PSD-MKO mice than in control muscles (Fig.…”

Section: Resultsmentioning

confidence: 99%

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

et al. 2019

View full text Add to dashboard Cite

Exercise capacity is a strong predictor of all-cause mortality. Skeletal muscle mitochondrial respiratory capacity, its biggest contributor, adapts robustly to changes in energy demands induced by contractile activity. While transcriptional regulation of mitochondrial enzymes has been extensively studied, there is limited information on how mitochondrial membrane lipids are regulated. Here, we show that exercise training or muscle disuse alters mitochondrial membrane phospholipids including phosphatidylethanolamine (PE). Addition of PE promoted, whereas removal of PE diminished, mitochondrial respiratory capacity. Unexpectedly, skeletal muscle–specific inhibition of mitochondria-autonomous synthesis of PE caused respiratory failure because of metabolic insults in the diaphragm muscle. While mitochondrial PE deficiency coincided with increased oxidative stress, neutralization of the latter did not rescue lethality. These findings highlight the previously underappreciated role of mitochondrial membrane phospholipids in dynamically controlling skeletal muscle energetics and function.

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Phospholipid requirements for the reconstitution of complex-III vesicles exhibiting controlled electron transport

Cited by 16 publications

References 25 publications

Dimeric ubiquinol:cytochrome c reductase of Neurospora mitochondria contains one cooperative ubiquinone‐reduction centre

Dimeric ubiquinol:cytochrome c reductase of Neurospora mitochondria contains one cooperative ubiquinone‐reduction centre

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

Mitochondrial PE potentiates respiratory enzymes to amplify skeletal muscle aerobic capacity

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