The role of the membrane bound cytochromes of b- and c-type in the electron transport chain of Rhodobacter capsulatus

1992 ◽  
Vol 157 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Davide Zannoni ◽  
Giovanni Venturoli ◽  
Fevzi Daldal
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Rhodobacter Capsulatus ◽  
Transport Chain ◽  
Membrane Bound

scholarly journals Heme Oxygenase-1 Supports Mitochondrial Energy Production and Electron Transport Chain Activity in Cultured Lung Epithelial Cells

2020 ◽  
Vol 21 (18) ◽  
pp. 6941
Author(s):  
Jennifer F. Carr ◽  
David Garcia ◽  
Alejandro Scaffa ◽  
Abigail L. Peterson ◽  
Andrew J. Ghio ◽  
...  
Keyword(s):  
Electron Transport ◽  
Heme Oxygenase ◽  
Electron Transport Chain ◽  
Iron Concentration ◽  
Heme Iron ◽  
Lung Epithelial Cells ◽  
Heme Oxygenase 1 ◽  
Protective Effects ◽  
Transport Chain

Heme oxygenase-1 is induced by many cellular stressors and catalyzes the breakdown of heme to generate carbon monoxide and bilirubin, which confer cytoprotection. The role of HO-1 likely extends beyond the simple production of antioxidants, for example HO-1 activity has also been implicated in metabolism, but this function remains unclear. Here we used an HO-1 knockout lung cell line to further define the contribution of HO-1 to cellular metabolism. We found that knockout cells exhibit reduced growth and mitochondrial respiration, measured by oxygen consumption rate. Specifically, we found that HO-1 contributed to electron transport chain activity and utilization of certain mitochondrial fuels. Loss of HO-1 had no effect on intracellular non-heme iron concentration or on proteins whose levels and activities depend on available iron. We show that HO-1 supports essential functions of mitochondria, which highlights the protective effects of HO-1 in diverse pathologies and tissue types. Our results suggest that regulation of heme may be an equally significant role of HO-1.

scholarly journals Tissue Factor Decryption By Oxidative Stress-Induced Lipid Peroxidation: Potential Mechanisms

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 125-125
Author(s):  
Shabbir Ansari ◽  
Usha R Pendurthi ◽  
L. Vijaya Mohan Rao
Keyword(s):  
Oxidative Stress ◽  
Electron Transport ◽  
P38 Mapk ◽  
Electron Transport Chain ◽  
Thioredoxin Reductase ◽  
Dependent Manner ◽  
Mapk Activation ◽  
Downstream Signaling ◽  
Transport Chain

Abstract Cellular lipid peroxidation is known to contribute to the initiation and propagation of atherothrombosis. Recently, we showed that 4-hydroxynonenal (HNE), one of the most abundant reactive aldehydes generated from the oxidation of ω-6 fatty acids, enhanced tissue factor (TF) activity on monocytic cells by externalizing phosphatidylserine (PS) in p38 MAPK activation-dependent manner. However, at present, the link between HNE-induced oxidative stress and p38 MAPK activation and the relation of p38 MAPK activation to PS externalization is not fully known. In the present study, we investigated the role of mitochondrial electron transport chain and reactive oxygen species (ROS) generation in HNE-mediated TF decryption. In addition, we also investigated the thioredoxin reductase-thioredoxin-ASK-1 axis in regulating p38 MAPK activation and PS externalization in decrypting TF. To elucidate potential mechanisms of HNE-induced TF decryption, we first determined the role of specific mitochondrial electron transport chain complexes in regulating TF activity. Since THP-1 cells used in the study had a measurable basal TF activity, they were not further treated with LPS or other agonists to induce TF synthesis. The electron transport chain in these cells was disrupted by specific inhibitors and cell surface TF activity was measured by factor X activation assay. Inhibition of complex I and complex IV by rotenone and sodium azide, respectively, enhanced the procoagulant activity of basal level TF. However, the inhibition of complex I and IV had no significant effect on the HNE-mediated increase in TF activity. Interestingly, inhibition of ATP synthase/complex V by oligomycin significantly inhibited the HNE-mediated enhanced TF activity, indicating that HNE-mediated TF decryption may involve the generation of ATP. In agreement with earlier published studies in monocytes/macrophages, stimulation of THP-1 cells with ATP increased cell surface TF activity. However, at present, it is yet to be shown that HNE treatment actually increased the production of ATP and that this ATP is responsible for the HNE-mediated TF decryption. It is also possible that HNE, either through a generation of ROS in mitochondria or directly, can affect the activity of thioredoxin either by intracellular signaling or by directly forming an adduct with it. Therefore, we next investigated the effect of HNE on the activity of thioredoxin reductase, the enzyme known to regulate thioredoxin activity in the cell. Our data showed that HNE treatment inhibited the activity of thioredoxin reductase in a concentration-dependent manner, 40 µM of HNE inhibiting 50% of the activity and a complete inhibition at 80µM of HNE. To further determine the downstream signaling cascade involved in the PS externalization and TF decryption on exposure to HNE, we analyzed the effect of HNE on the activation of MKK3 and MKK6, the protein kinases known to activate p38 MAPK and the downstream signaling activator of thioredoxin/thioredoxin reductase pathway. HNE treatment increased the phosphorylation of MKK3 and MKK6 in a time-dependent manner. In summary, our data suggest that HNE may mediate TF decryption via modulation of thioredoxin/thioredoxin reductase system, which results in activation of MKK3/MKK6, which in turn activates p38 MAPK that is responsible for PS externalization. The study highlights the potential role of oxidative stress in regulating TF activity in thrombotic disorders and provides a mechanistic link between disorders associated with cellular oxidative stress and thrombosis. Disclosures No relevant conflicts of interest to declare.

Glycine Decarboxylation in Mitochondria Isolated from Spinach Leaves

1976 ◽  
Vol 3 (6) ◽  
pp. 771
Author(s):  
K.C Woo ◽  
C.B Osmond
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Exchange Reactions ◽  
Transport Chain ◽  
Lipoamide Dehydrogenase ◽  
Mitochondrial Malate Dehydrogenase ◽  
Acid Stable ◽  
Spinach Leaves

Mitochondria isolated from spinach leaves contain at least two glycine decarboxylating systems. One system is stimulated by ADP and evidently couples to the electron transport chain. The other system, three times as active, is stimulated by NAD+ and oxaloacetate and is not coupled directly to electron transport; however, comparative studies with uncouplers and inhibitors indicate it may depend on a membrane potential generated by electron transport. In this system, the role of oxaloacetate appears to be the regeneration of NAD+, via mitochondrial malate dehydrogenase, as an electron acceptor during glycine decarboxylation. Mitochondria isolated from spinach leaves also catalyse a rapid glycine-dependent exchange of bicarbonate into acid-stable products. This reaction is stimulated by the addition of lipoamide dehydrogenase. The activity of the glycine decarboxylation and exchange reactions are irreversibly lost when mitochondria are broken. When corrections are applied to account for mitochondrial breakage, the rates of glycine decarboxylation and the exchange reaction are comparable to the rates of CO*2 evolution from leaves of C*3 plants in air. The role of these processes in vivo and relationship to other sources of CO*2 in the glycollate pathway are discussed.

CELL AGGREGATION OF THE CYANOBACTERIUM SYNECHOCOCCUS ELONGATUS : ROLE OF THE ELECTRON TRANSPORT CHAIN

2000 ◽  
Vol 36 (4) ◽  
pp. 662-668 ◽  
Author(s):  
Michal Koblížek ◽  
Josef Komenda ◽  
Jiří Masojídek ◽  
Libor Pechar
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Cell Aggregation ◽  
Synechococcus Elongatus ◽  
Transport Chain
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