Functional Expression of Electron Transport Chain and FoF1-ATP Synthase in Optic Nerve Myelin Sheath

2015 ◽  
Vol 40 (11) ◽  
pp. 2230-2241 ◽  
Author(s):  
Martina Bartolucci ◽  
Silvia Ravera ◽  
Greta Garbarino ◽  
Paola Ramoino ◽  
Sara Ferrando ◽  
...  
Keyword(s):  
Electron Transport ◽  
Optic Nerve ◽  
Atp Synthase ◽  
Myelin Sheath ◽  
Electron Transport Chain ◽  
Functional Expression ◽  
Transport Chain ◽  
Fof1 Atp Synthase

The efficiency and plasticity of mitochondrial energy transduction

2005 ◽  
Vol 33 (5) ◽  
pp. 897-904 ◽  
Author(s):  
M.D. Brand
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Uncoupling Protein ◽  
Coupling Efficiency ◽  
Energy Transduction ◽  
Proton Pumping ◽  
Complex Iii ◽  
Proton Pumps ◽  
Transport Chain

Since it was first realized that biological energy transduction involves oxygen and ATP, opinions about the amount of ATP made per oxygen consumed have continually evolved. The coupling efficiency is crucial because it constrains mechanistic models of the electron-transport chain and ATP synthase, and underpins the physiology and ecology of how organisms prosper in a thermodynamically hostile environment. Mechanistically, we have a good model of proton pumping by complex III of the electron-transport chain and a reasonable understanding of complex IV and the ATP synthase, but remain ignorant about complex I. Energy transduction is plastic: coupling efficiency can vary. Whether this occurs physiologically by molecular slipping in the proton pumps remains controversial. However, the membrane clearly leaks protons, decreasing the energy funnelled into ATP synthesis. Up to 20% of the basal metabolic rate may be used to drive this basal leak. In addition, UCP1 (uncoupling protein 1) is used in specialized tissues to uncouple oxidative phosphorylation, causing adaptive thermogenesis. Other UCPs can also uncouple, but are tightly regulated; they may function to decrease coupling efficiency and so attenuate mitochondrial radical production. UCPs may also integrate inputs from different fuels in pancreatic β-cells and modulate insulin secretion. They are exciting potential targets for treatment of obesity, cachexia, aging and diabetes.

Localized energy coupling during photophosphorylation by chromatophores of Rhodopseudomonas capsulata N22

1982 ◽  
Vol 2 (10) ◽  
pp. 743-749 ◽  
Author(s):  
G. Duncan Hitchens ◽  
Douglas B. Kell
Keyword(s):  
Free Energy ◽  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Energy Coupling ◽  
Rhodopseudomonas Capsulata ◽  
Titration Method ◽  
Dual Inhibitor ◽  
Transport Chain ◽  
Synthase Inhibitor

The principle of the dual inhibitor titration method for testing models of electron-transport phosphorylation is outlined, and the method is applied to the study of photophosphorylation in bacterial chromatophores. It is concluded that energy coupling is strictly localized in nature in this system, in the sense that free energy released by a particular electron-transport chain may be used only by a particular H+-ATP synthase. Dual inhibitor titrations using the uncoupler SF 6847 and the H+-ATP synthase inhibitor oligomycin indicate that uncouplers act by shuttling rapidly between the localized energy-coupling sites.

scholarly journals Functional characterization of mutants deficient in N-terminal phosphorylation of the CF1 subunit beta

2021 ◽  
Author(s):  
Ralph Bock ◽  
Deserah D Strand ◽  
Daniel Karcher ◽  
Stephanie Ruf ◽  
Anne Schadach ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Atp Hydrolysis ◽  
Molecular Motor ◽  
Functional Characterization ◽  
Phosphorylation Sites ◽  
Transport Chain

Understanding the regulation of photosynthetic light harvesting and electron transfer is of great importance to efforts to improve the ability of the electron transport chain to supply downstream metabolism. The central regulator of the electron transport chain is the ATP synthase, the molecular motor that harnesses the chemiosmotic potential generated from proton coupled electron transport to synthesize ATP. The ATP synthase is regulated both thermodynamically and post-translationally, with proposed phosphorylation sites on multiple subunits. In this study we focused on two N-terminal serines on the catalytic subunit beta, previously proposed to be important for dark inactivation of the complex to avoid ATP hydrolysis at night. Here we show that there is no clear role for phosphorylation in the dark inactivation of ATP synthase. Instead, mutation of one of the two phosphorylated serine residues to aspartate strongly decreased ATP synthase abundance. We propose that the loss of N-terminal phosphorylation of ATP beta may be involved in proper ATP synthase accumulation during complex assembly.

scholarly journals On the extent of localization of the energized membrane state in chromatophores from Rhodopseudomonas capsulata N22

1982 ◽  
Vol 206 (2) ◽  
pp. 351-357 ◽  
Author(s):  
G D Hitchens ◽  
D B Kell
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Relative Number ◽  
Coupling Model ◽  
Rhodopseudomonas Capsulata ◽  
Apparent Paradox ◽  
Model Free ◽  
Transport Chain ◽  
Chemiosmotic Coupling

1. The principle of the double-inhibitor titration method for assessing competing models of electron transport phosphorylation is expounded. 2. This principle is applied to photophosphorylation by chromatophores from Rhodopseudomonas capsulata N22. 3. It is found that, in contrast to the predictions of the chemiosmotic coupling model, free energy transfer is confined to individual electron transport chain and ATP synthase complexes. 4. This conclusion is not weakened by arguments concerning, the degree of uncoupling in the native chromatophore preparation or the relative number of electron transport chain and ATP synthase complexes present. 5. Photophosphorylation is completely inhibited by the uncoupler SF 6847 at a concentration corresponding to 0.31 molecules per electron transport chain. 6. The apparent paradox is solved by the proposal, consistent with the available evidence on the mode of action of uncouplers, that uncoupler binding causes a co-operative conformation transition in the chromatophore membrane, which leads to uncoupling and which is not present in the absence of uncoupler.

Functional expression of electron transport chain complexes in mouse rod outer segments

Biochimie ◽  
2014 ◽  
Vol 102 ◽  
pp. 78-82 ◽  
Author(s):  
Daniela Calzia ◽  
Greta Garbarino ◽  
Federico Caicci ◽  
Lucia Manni ◽  
Simona Candiani ◽  
...  
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Functional Expression ◽  
Rod Outer Segments ◽  
Outer Segments ◽  
Chain Complexes ◽  
Transport Chain

scholarly journals Regulation of COX Assembly and Function by Twin CX9C Proteins—Implications for Human Disease

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 197
Author(s):  
Stephanie Gladyck ◽  
Siddhesh Aras ◽  
Maik Hüttemann ◽  
Lawrence I. Grossman
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Atp Synthase ◽  
Protein Interactions ◽  
Human Disease ◽  
Electron Transport Chain ◽  
Intermembrane Space ◽  
Protein Protein Interactions ◽  
Inner Mitochondrial Membrane ◽  
Transport Chain

Oxidative phosphorylation is a tightly regulated process in mammals that takes place in and across the inner mitochondrial membrane and consists of the electron transport chain and ATP synthase. Complex IV, or cytochrome c oxidase (COX), is the terminal enzyme of the electron transport chain, responsible for accepting electrons from cytochrome c, pumping protons to contribute to the gradient utilized by ATP synthase to produce ATP, and reducing oxygen to water. As such, COX is tightly regulated through numerous mechanisms including protein–protein interactions. The twin CX9C family of proteins has recently been shown to be involved in COX regulation by assisting with complex assembly, biogenesis, and activity. The twin CX9C motif allows for the import of these proteins into the intermembrane space of the mitochondria using the redox import machinery of Mia40/CHCHD4. Studies have shown that knockdown of the proteins discussed in this review results in decreased or completely deficient aerobic respiration in experimental models ranging from yeast to human cells, as the proteins are conserved across species. This article highlights and discusses the importance of COX regulation by twin CX9C proteins in the mitochondria via COX assembly and control of its activity through protein–protein interactions, which is further modulated by cell signaling pathways. Interestingly, select members of the CX9C protein family, including MNRR1 and CHCHD10, show a novel feature in that they not only localize to the mitochondria but also to the nucleus, where they mediate oxygen- and stress-induced transcriptional regulation, opening a new view of mitochondrial-nuclear crosstalk and its involvement in human disease.

A regulatory effect of the electron-transport chain on ATP synthase

1986 ◽  
Vol 14 (1) ◽  
pp. 33-33
Author(s):  
BERNHARD HUCHZERMEYER ◽  
EVA HEINRICH
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Regulatory Effect ◽  
Transport Chain

Downregulation of diaphragm electron transport chain and glycolytic enzyme gene expression in sepsis

2005 ◽  
Vol 99 (3) ◽  
pp. 1120-1126 ◽  
Author(s):  
Leigh Ann Callahan ◽  
Gerald S. Supinski
Keyword(s):  
Gene Expression ◽  
Energy Metabolism ◽  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Cellular Energy ◽  
Protein Levels ◽  
Cellular Energy Metabolism ◽  
Transport Chain ◽  
Genes Encoding

Cellular energy metabolism is altered in sepsis as a consequence of dysfunction of mitochondrial electron transport and glycolytic pathways. The purpose of the present study was to determine whether sepsis is associated with compensatory increases in gene expression of electron transport chain and glycolytic pathway proteins or, alternatively, whether gene expression decreases in sepsis, contributing to abnormalities in energy metabolism. Studies were performed using diaphragms from control and endotoxin-treated (8 mg·kg−1·day−1) rats; at 48 h after endotoxin administration, animals were killed. Microarrays and RNAse protection assays were used to assess the expression of several electron transport chain components (cytochrome- c oxidase subunits Cox 5A, Cox 5B, and Cox 6A, ATP synthase, and ATP synthase subunit 5B) and of the rate-limiting enzyme for glycolysis, phosphofructokinase (PFK). Western blotting was used to assess protein levels for these electron transport chain subunits and PFK. Activity assays were used to assess electron transport chain and phosphofructokinase function. We found that sepsis evoked 1) a downregulation of genes encoding all examined electron transport chain components (e.g., cytochrome- c oxidase 5A decreased 45 + 7%, P < 0.01) and PFK ( P < 0.001), 2) reductions in protein levels for these electron transport chain subunits and PFK ( P < 0.05 for each), and 3) decreases in mitochondrial state 3 respiration rates and phosphofructokinase enzyme activity ( P < 0.01 for each comparison). We speculate that these sepsis-induced reductions in the expression of genes encoding critical electron transport and glycolytic proteins contribute to the development and persistence of sepsis-induced abnormalities in cellular energy metabolism.

scholarly journals Isoniazid Bactericidal Activity Involves Electron Transport Chain Perturbation

2019 ◽  
Vol 63 (3) ◽  
Author(s):  
Sheng Zeng ◽  
Karine Soetaert ◽  
Faustine Ravon ◽  
Marie Vandeput ◽  
Dirk Bald ◽  
...  
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Bactericidal Activity ◽  
Electron Transport Chain ◽  
Acid Synthesis ◽  
Mycolic Acid ◽  
Stress Conditions ◽  
Cell Recovery ◽  
Content Type ◽  
Transport Chain

ABSTRACTAccumulating evidence suggests that the bactericidal activity of some antibiotics may not be directly initiated by target inhibition. The activity of isoniazid (INH), a key first-line bactericidal antituberculosis drug currently known to inhibit mycolic acid synthesis, becomes extremely poor under stress conditions, such as hypoxia and starvation. This suggests that the target inhibition may not fully explain the bactericidal activity of the drug. Here, we report that INH rapidly increasedMycobacterium bovisBCG cellular ATP levels and enhanced oxygen consumption. The INH-triggered ATP increase and bactericidal activity were strongly compromised by Q203 and bedaquiline, which inhibit mycobacterial cytochromebc1and FoF1ATP synthase, respectively. Moreover, the antioxidantN-acetylcysteine (NAC) but not 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPOL) abrogated the INH-triggered ATP increase and killing. These results reveal a link between the energetic (ATP) perturbation and INH’s killing. Furthermore, the INH-induced energetic perturbation and killing were also abrogated by chemical inhibition of NADH dehydrogenases (NDHs) and succinate dehydrogenases (SDHs), linking INH’s bactericidal activity further to the electron transport chain (ETC) perturbation. This notion was also supported by the observation that INH dissipated mycobacterial membrane potential. Importantly, inhibition of cytochromebdoxidase significantly reduced cell recovery during INH challenge in a culture settling model, suggesting that the respiratory reprogramming to the cytochromebdoxidase contributes to the escape of INH killing. This study implicates mycobacterial ETC perturbation through NDHs, SDHs, cytochromebc1, and FoF1ATP synthase in INH’s bactericidal activity and pinpoints the participation of the cytochromebdoxidase in protection against this drug under stress conditions.

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