scholarly journals Reconstitution of oxidative phosphorylation and the adenosine triphosphate-dependent transhydrogenase activity by a combination of membrane fractions from uncA− and uncB− mutant strains of Escherichia coli K12

1973 ◽  
Vol 134 (4) ◽  
pp. 1015-1021 ◽  
Author(s):  
G. B. Cox ◽  
F. Gibson ◽  
L. McCann
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Membrane System ◽  
Normal Strain ◽  
Escherichia Coli K12 ◽  
Functional Relationships ◽  
Transport Chain ◽  
Mutant Strains ◽  
Low Ionic Strength

1. Membrane preparations from both uncA− and uncB− mutant strains of Escherichia coli K12, in which electron transport is uncoupled from phosphorylation, were fractionated by washing with a low-ionic-strength buffer. The fractionation gave a `5mm-Tris wash' and a `membrane residue' from each strain. This technique, applied to membranes from normal cells, separates the Mg2+,Ca2+-stimulated adenosine triphosphatase activity from the membrane-bound electron-transport chain and the non-energy-linked transhydrogenase activity. 2. Reconstitution of both oxidative phosphorylation and the ATP-dependent transhydrogenase activity was obtained by a combination of the `membrane residue' from strain AN249 (uncA−) with the `5mm-Tris wash' from strain AN283 (uncB−). 3. Valinomycin plus NH4+ inhibited oxidative phosphorylation both in membranes from a normal strain of E. coli and in the reconstituted membrane system derived from the mutant strains. 4. The electron-transport-dependent transhydrogenase activity was located in the membrane residue and was de-repressed in both the mutant strains. 5. The spatial and functional relationships between the proteins specified by the uncA and uncB genes and the transhydrogenase protein are discussed.

scholarly journals Effects of sulphate-limited growth in continuous culture on the electron-transport chain and energy conservation in Escherichia coli K12

1975 ◽  
Vol 152 (3) ◽  
pp. 537-546 ◽  
Author(s):  
R K Poole ◽  
B A Haddock
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Functional Organization ◽  
Extracellular Polysaccharide ◽  
Limited Growth ◽  
Escherichia Coli K12 ◽  
Transport Chain ◽  
Respiratory Chains ◽  
Energy Dependent

Growth of Escherichia coli K12 in a chemostat was limited by sulphate concentrations lower than 300 muM. The synthesis of extracellular polysaccharide and a change in morphology accompanied sulphate-limited growth. Growth yields with respect to the amount of glycerol or oxygen consumed were sixfold and twofold lower respectively under these conditions than when growth was limited by glycerol. Sulphate-limited cells lacked the proton-translocating oxidoreduction segment of the electron-transport chain between NADH and the cytochromes, and particles prepared from these cells lacked the energy-dependent reduction of NAD+ by succinate, DL-α-glycerophosphate or D-lactate, suggesting the loss of site-I phosphorylation. Glycerol-limited cells contained cytochrome b556, b562 and o, ubiquinone and low concentrations of menaquinone. Sulphate limitation resulted in the additional synthesis of cytochromes d, a1, b558 and c550; the amount of ubiquinone was decreased and menaquinone was barely detectable. Non-haem iron and acid-labile sulphide concentrations were twofold lower in electron-transport particles prepared from sulphate-limited cells. Recovery of site-I phosphorylation could not be demonstrated after incubating sulphate-limited cells with or without glycerol, in either the absence or presence of added sulphate. The loss of site-I phosphorylation in sulphate-limited cells is discussed with reference to the accompanying alterations in cytochrome composition of such cells. Schemes are proposed for the functional organization of the respiratory chains of E. coli grown under conditions of glycerol or sulphate limitation.

scholarly journals The energy-linked transhydrogenase reaction in respiratory mutants of Escherichia coli K 12

1971 ◽  
Vol 125 (2) ◽  
pp. 489-493 ◽  
Author(s):  
G. B. Cox ◽  
N. A. Newton ◽  
J. D. Butlin ◽  
F. Gibson
Keyword(s):  
Escherichia Coli ◽  
Energy Source ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Adenosine Triphosphatase ◽  
E Coli ◽  
Transport Chain ◽  
Mutant Strains ◽  
K 12 ◽  
A Site

1. Energy-linked and non-energy-linked transhydrogenase activities were assayed in membrane preparations from normal Escherichia coli K 12 and from various mutant strains. 2. The energy-linked transhydrogenase, which uses ATP as energy source, was dependent for activity on the presence of a functional Mg2++Ca2+-stimulated adenosine triphosphatase. 3. Neither of the quinones formed by E. coli, namely ubiquinone-8 and menaquinone-8, was required for normal ATP-dependent energy-linked transhydrogenase activity. 4. The energy-linked transhydrogenase was inhibited by piericidin A at a site unrelated to the sites of inhibition of the electron-transport chain by piericidin A.

scholarly journals Characterization of the mutant-unc D-gene product in a strain of Escherichia coli K12. An altered β-subunit of the magnesium ion-stimulated adenosine triphosphatase

1978 ◽  
Vol 172 (3) ◽  
pp. 523-531 ◽  
Author(s):  
D R H Fayle ◽  
J A Downie ◽  
G B Cox ◽  
F Gibson ◽  
J Radik
Keyword(s):  
Escherichia Coli ◽  
Adenosine Triphosphatase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Beta Subunit ◽  
Beta Subunits ◽  
Normal Strain ◽  
Diploid Strain ◽  
Escherichia Coli K12 ◽  
Low Ionic Strength

Membranes from a mutant strain of Escherichia coli K12 carrying the uncD409 allele were washed in low-ionic-strength buffers in the presence or absence of the proteinase inhibitor p-aminobenzamidine. Unlike membranes from a normal strain, those from strain AN463 (uncD409) did not become proton-permeable, as judged by NADH-induced atebrinfluorescence quenching, when the membranes were washed in the absence of p-aminobenzamide. Furthermore, ATP-dependent atebrin-fluorscence quenching in such washed membranes could not be reconstituted by the addition of solubilized Mg2+-stimulated adenosine triphosphatase preparations. The examination by two-dimensional polyacrylamide-gel electrophoresis of the polypeptide composition of the washed membranes from strain AN463 (uncD409) indicated the presence of a polypeptide of similar molecular weight to the normal beta-subunit of the Mg2+-stimulated adenosine triphosphatase, but with an altered isoelectric point. Both the normal and abnormal beta-subunits were identified in membranes prepared from a partial diploid strain carrying both the unc+ and uncD409 alleles. It is concluded that the uncD gene codes for the beta-subunit of the Mg2+-stimulated adenosine triphosphatase.

scholarly journals Metabolite transport in mutants of Escherichia coli K12 defective in electron transport and coupled phosphorylation

1975 ◽  
Vol 146 (2) ◽  
pp. 417-423 ◽  
Author(s):  
H Rosenberg ◽  
G B Cox ◽  
J D Butlin ◽  
S J Gutowski
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Active Transport ◽  
Adenosine Triphosphatase ◽  
Minimal Medium ◽  
Sole Source ◽  
Whole Cells ◽  
Escherichia Coli K12 ◽  
Mutant Strains ◽  
Uptake Medium

1. The uptakes of Pi and serine by whole cells of mutant strains of Escherichia coli K12, grown under both aerobic and anaerobic conditions, were studied. 2. Uptake by aerobic cells was low in a ubiquinone-less mutant but normal in two mutant strains unable to couple phosphorylation to electron transport. 3. One of these uncoupled strains, carrying the unc-405 allele, does not form a membrane-bound Mg2+-stimulated adenosine triphosphatase aggregate, and it is concluded that the Mg2+-stimulated adenosine triphosphatase does not serve a structural role in the aerobic active transport of Pi or serine. 4. The other uncoupled strain, in which aerobic uptake is unaffected, carries a mutation in the uncB gene, thus distinguishing this gene from the etc gene, previously shown to be concerned with the coupling of electron transport to active transport. 5. The uptakes of Pi and serine by anaerobic cells were normal in the ubiquinone-less mutant, but defective in both the uncoupled strains. 6. The uptake of Pi and serine by anaerobic cells of the uncB mutant could be increased by the addition of fumarate to the uptake medium. The unc-405 mutant, however, required the addition of fumarate for growth and for uptake. 7. The uncB mutant, unlike the unc-405 mutant, is able to grow anaerobically in a minimal medium with glucose as sole source of carbon. Similarly a strain carrying a mutation in the frd gene, which is the structural gene for the enzyme fumarate reductase, is able to grow anaerobically in a glucose-minimal medium. However, a mutant strain carrying mutations in both the uncB and frd genes resembles the unc-405 mutant in not being able to grow under these conditions.

scholarly journals Physiological Evidence for Isopotential Tunneling in the Electron Transport Chain of Methane-Producing Archaea

2017 ◽  
Vol 83 (18) ◽  
Author(s):  
Nikolas Duszenko ◽  
Nicole R. Buan
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Electron Transport Chain ◽  
Methanosarcina Barkeri ◽  
Metabolic Efficiency ◽  
Methanosarcina Acetivorans ◽  
Content Type ◽  
Transport Chain

ABSTRACT Many, but not all, organisms use quinones to conserve energy in their electron transport chains. Fermentative bacteria and methane-producing archaea (methanogens) do not produce quinones but have devised other ways to generate ATP. Methanophenazine (MPh) is a unique membrane electron carrier found in Methanosarcina species that plays the same role as quinones in the electron transport chain. To extend the analogy between quinones and MPh, we compared the MPh pool sizes between two well-studied Methanosarcina species, Methanosarcina acetivorans C2A and Methanosarcina barkeri Fusaro, to the quinone pool size in the bacterium Escherichia coli. We found the quantity of MPh per cell increases as cultures transition from exponential growth to stationary phase, and absolute quantities of MPh were 3-fold higher in M. acetivorans than in M. barkeri. The concentration of MPh suggests the cell membrane of M. acetivorans, but not of M. barkeri, is electrically quantized as if it were a single conductive metal sheet and near optimal for rate of electron transport. Similarly, stationary (but not exponentially growing) E. coli cells also have electrically quantized membranes on the basis of quinone content. Consistent with our hypothesis, we demonstrated that the exogenous addition of phenazine increases the growth rate of M. barkeri three times that of M. acetivorans. Our work suggests electron flux through MPh is naturally higher in M. acetivorans than in M. barkeri and that hydrogen cycling is less efficient at conserving energy than scalar proton translocation using MPh. IMPORTANCE Can we grow more from less? The ability to optimize and manipulate metabolic efficiency in cells is the difference between commercially viable and nonviable renewable technologies. Much can be learned from methane-producing archaea (methanogens) which evolved a successful metabolic lifestyle under extreme thermodynamic constraints. Methanogens use highly efficient electron transport systems and supramolecular complexes to optimize electron and carbon flow to control biomass synthesis and the production of methane. Worldwide, methanogens are used to generate renewable methane for heat, electricity, and transportation. Our observations suggest Methanosarcina acetivorans, but not Methanosarcina barkeri, has electrically quantized membranes. Escherichia coli, a model facultative anaerobe, has optimal electron transport at the stationary phase but not during exponential growth. This study also suggests the metabolic efficiency of bacteria and archaea can be improved using exogenously supplied lipophilic electron carriers. The enhancement of methanogen electron transport through methanophenazine has the potential to increase renewable methane production at an industrial scale.

scholarly journals Anesthesia-Sepsis-Associated Alterations in Liver Gene Expression Profiles and Mitochondrial Oxidative Phosphorylation Complexes

2020 ◽  
Vol 7 ◽  
Author(s):  
Hari Prasad Osuru ◽  
Umadevi Paila ◽  
Keita Ikeda ◽  
Zhiyi Zuo ◽  
Robert H. Thiele
Keyword(s):  
Gene Expression ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Electron Transport Chain ◽  
Expression Profiles ◽  
Volatile Anesthetic ◽  
Heme Oxygenase 1 ◽  
Complex Ii ◽  
Transport Chain ◽  
The Impact

Background: Hepatic dysfunction plays a major role in adverse outcomes in sepsis. Volatile anesthetic agents may protect against organ dysfunction in the setting of critical illness and infection. The goal of this study was to study the impact of Sepsis-inflammation on hepatic subcellular energetics in animals anesthetized with both Propofol (intravenous anesthetic agent and GABA agonist) and Isoflurane (volatile anesthetic i.e., VAA).Methods: Sprague-Dawley rats were anesthetized with Propofol or isoflurane. Rats in each group were randomized to celiotomy and closure (control) or cecal ligation and puncture “CLP” (Sepsis-inflammation) for 8 h.Results: Inflammation led to upregulation in hepatic hypoxia-inducible factor-1 in both groups. Rats anesthetized with isoflurane also exhibited increases in bcl-2, inducible nitric oxide synthase, and heme oxygenase-1(HO-1) during inflammation, whereas rats anesthetized with Propofol did not. In rats anesthetized with isoflurane, decreased mRNA, protein (Complex II, IV, V), and activity levels (Complex II/III,IV,V) were identified for all components of the electron transport chain, leading to a decrease in mitochondrial ATP. In contrast, in rats anesthetized with Propofol, these changes were not identified after exposure to inflammation. RNA-Seq and real-time quantitative PCR (qPCR) expression analysis identified a substantial difference between groups (isoflurane vs. Propofol) in mitogen-activated protein kinase (MAPK) related gene expression following exposure to Sepsis-inflammation.Conclusions: Compared to rats anesthetized with Propofol, those anesthetized with isoflurane exhibit more oxidative stress, decreased oxidative phosphorylation protein expression, and electron transport chain activity and increased expression of organ-protective proteins.

scholarly journals Stress signalling dynamics of the mitochondrial electron transport chain and oxidative phosphorylation system in higher plants

2019 ◽  
Vol 125 (5) ◽  
pp. 721-736 ◽  
Author(s):  
Corentin Dourmap ◽  
Solène Roque ◽  
Amélie Morin ◽  
Damien Caubrière ◽  
Margaux Kerdiles ◽  
...  
Keyword(s):  
Climate Change ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Electron Transport Chain ◽  
Plant Mitochondria ◽  
Mitochondrial Electron Transport Chain ◽  
Oxidative Phosphorylation System ◽  
Transport Chain ◽  
Wide Range ◽  
Stress Signalling

Abstract Background Mitochondria play a diversity of physiological and metabolic roles under conditions of abiotic or biotic stress. They may be directly subjected to physico-chemical constraints, and they are also involved in integrative responses to environmental stresses through their central position in cell nutrition, respiration, energy balance and biosyntheses. In plant cells, mitochondria present various biochemical peculiarities, such as cyanide-insensitive alternative respiration, and, besides integration with ubiquitous eukaryotic compartments, their functioning must be coupled with plastid functioning. Moreover, given the sessile lifestyle of plants, their relative lack of protective barriers and present threats of climate change, the plant cell is an attractive model to understand the mechanisms of stress/organelle/cell integration in the context of environmental stress responses. Scope The involvement of mitochondria in this integration entails a complex network of signalling, which has not been fully elucidated, because of the great diversity of mitochondrial constituents (metabolites, reactive molecular species and structural and regulatory biomolecules) that are linked to stress signalling pathways. The present review analyses the complexity of stress signalling connexions that are related to the mitochondrial electron transport chain and oxidative phosphorylation system, and how they can be involved in stress perception and transduction, signal amplification or cell stress response modulation. Conclusions Plant mitochondria are endowed with a diversity of multi-directional hubs of stress signalling that lead to regulatory loops and regulatory rheostats, whose functioning can amplify and diversify some signals or, conversely, dampen and reduce other signals. Involvement in a wide range of abiotic and biotic responses also implies that mitochondrial stress signalling could result in synergistic or conflicting outcomes during acclimation to multiple and complex stresses, such as those arising from climate change.

Mitochondrial Disorder for Muscle Biopsy

2013 ◽  
Author(s):  
J. Fay Jou ◽  
Lori A Aronson ◽  
Jacqueline W Morillo-Delerme
Keyword(s):  
Energy Metabolism ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Disease ◽  
Electron Transport Chain ◽  
Mitochondrial Disorder ◽  
Metabolic Complications ◽  
Transport Chain ◽  
Increased Risk ◽  
Anesthetic Considerations

Mitochondrial disease (mtD) is a genetically, biochemically, and clinically heterogeneous group of disorders that arise most commonly from defects in the oxidative phosphorylation or electron transport chain involved in energy metabolism. These patients have an increased risk for cardiac, respiratory, neurologic, and metabolic complications from anesthesia. Consequently, there are several anesthetic considerations for patients with mtD.

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