Effect of growth conditions on the involvement of cytochrome c in electron transport, proton translocation and ATP synthesis in the facultative methylotroph Pseudomonas AM1

1979 ◽  
Vol 182 (3) ◽  
pp. 641.b3-641.b3
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Proton Translocation ◽  
Atp Synthesis ◽  
Growth Conditions ◽  
Facultative Methylotroph

scholarly journals Effect of growth conditions on the involvement of cytochrome c in electron transport, proton translocation and ATP synthesis in the facultative methylotroph Pseudomonas AM1

1979 ◽  
Vol 182 (1) ◽  
pp. 71-79 ◽  
Author(s):  
C. William Keevil ◽  
Christopher Anthony
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Proton Translocation ◽  
Atp Synthesis ◽  
Growth Conditions ◽  
Wild Type ◽  
Limited Growth ◽  
Bacterial Membranes ◽  
Facultative Methylotroph ◽  
Carbon Excess

The stoicheiometry of proton translocation, the amounts of cytochromes firmly bound to membranes, and cell yields with respect to succinate and O2 have been measured in the facultative methylotroph Pseudomonas AM1 and in the mutant lacking cytochrome c (mutant PCT76) during carbon-limited growth and carbon-excess growth. →H+/O ratios during endogenous respiration of about 4 were measured in wild-type bacteria grown in carbon-excess conditions, and in the mutant in all growth conditions. During methanol- or succinate-limited growth of wild-type bacteria the →H+/O ratio increased to about 6. Cell yields with respect to succinate and O2 were higher in wild-type than in the mutant lacking cytochrome c by an amount suggesting loss in the mutant of 30% of the ATP-generating capacity of wild-type bacteria. During carbon-limited growth on methanol or succinate some cytochrome c was tightly bound to bacterial membranes, whereas none was tightly bound in bacteria grown in batch-culture or in NH4+-limited conditions. It is proposed that the role of cytochrome c in Pseudomonas AM1 depends on growth conditions and hence on the ‘needs’ of the bacteria. During growth in carbon-excess conditions it is only required for methanol oxidation, mediating between methanol dehydrogenase and cytochrome a/a3. In these conditions oxidation of NADH and succinate by way of cytochrome b and cytochrome a/a3 occurs without the mediation of cytochrome c. This is the only route for oxidation of NADH and succinate in the cytochrome c-deficient mutant in all growth conditions. During carbon-limited growth the cytochrome c becomes bound to the membrane in such a way that it can mediate between cytochromes b and a/a3, hence becoming involved in proton translocation and ATP synthesis during NADH and succinate oxidation. An alternative possibility is that in wild-type bacteria the cytochrome c is always involved in electron transport, but that its involvement in measurable proton translocation only occurs in carbon-limited conditions.

Electron Transport and Coupled Energy Generation in Pseudomonas saccharophila

1971 ◽  
Vol 49 (11) ◽  
pp. 1175-1182 ◽  
Author(s):  
M. Ishaque ◽  
A. Donawa ◽  
M. I. H. Aleem
Keyword(s):  
Oxygen Consumption ◽  
Electron Transport ◽  
Cytochrome C ◽  
Atp Synthesis ◽  
Succinate Oxidation ◽  
Atp Formation ◽  
Low Concentrations ◽  
Oxidase Enzyme ◽  
Succinate Oxidase ◽  
Pseudomonas Saccharophila

The respiratory chain system of heterotrophically grown Pseudomonas saccharophila contained cytochromes of the b, c, a, and o types and also the NADH and succinate oxidase enzyme systems. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of NADH, succinate, and ascorbate (plus cytochrome c). The P/O ratios were in the range of 1.00 for generated NADH, 0.29 for added NADH, 0.50 for succinate, and 0.25 for ascorbate (plus cytochrome c).The oxidative phosphorylation was uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonyl cyanide phenylhydrazone, and dicumarol without any inhibition of oxygen consumption. Phosphorylation coupled to NADH oxidation was completely inhibited by the flavoprotein inhibitors such as rotenone, amytal, and atabrine; these inhibitors had no effect, however, on the ATP synthesis associated with succinate oxidation. Antimycin A or 2-n-nonyl-4-hydroxyquinoline-N-oxide as well as cyanide or azide at low concentrations completely inhibited the phosphate esterification coupled to the oxidation of NADH or succinate, but had little or no effect on the oxygen consumption. Relatively higher concentrations of oligomycin were required for a complete inhibition of the electron-transport-linked ATP formation.

Ultrastructural Cytochemistry of Some Oxidative Enzymes

1974 ◽  
Vol 32 ◽  
pp. 322-323
Author(s):  
Arnold M. Seligman
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Succinic Dehydrogenase ◽  
Atp Synthesis ◽  
Oxidative Enzymes ◽  
Reaction Products ◽  
Inner Mitochondrial Membrane ◽  
Design And Synthesis ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

The membrane-bound enzymes of the succinic oxidase chain of electron transport on the cristae of mitochondria have been the target of ultrastructural cytochemical research for a number of years. Methods for succinic dehydrogenase have been improved by the continuous design and synthesis of better tetrazolium salts. The most recent is BSPT, which is not osmiophilic, but yields an osmiophilic, lipophobic, insoluble formazan. The terminal triplet of the chain of electron transport or cytochrome oxidase, consisting of cytochrome c, a and a3 has been demonstrated very well via cytochrome c with diaminobenzidine (DAB). The localization of these two reaction products specifically on the outer surface of the inner mitochondrial membrane, lends some support to speculation concerning the mechanism of transfer of oxidative energy for ATP synthesis.

scholarly journals The presence of two cytochromes b in the facultative methylotroph Pseudomonas AM1

1979 ◽  
Vol 180 (1) ◽  
pp. 237-239 ◽  
Author(s):  
C W Keevil ◽  
C Anthony
Keyword(s):  
Cytochrome C ◽  
Continuous Culture ◽  
Batch Culture ◽  
Growth Conditions ◽  
Redox Potentials ◽  
Deficient Mutant ◽  
Facultative Methylotroph

Two cytochromes b with absorption maxima at 555 and 562 nm and differing in their mid-point redox potentials are synthesized in Pseudomonas AM1 during growth on methanol or succinate in batch culture, or in NH4+-limited or carbon-limited continuous culture. Both cytochromes b were also present in a cytochrome c-deficient mutant in all growth conditions.

scholarly journals The effect of cytochrome c and its ‘dimer’ on electron transfer and energy transformation

1972 ◽  
Vol 126 (3) ◽  
pp. 709-716 ◽  
Author(s):  
T. Shur-Perek ◽  
Y. Avi-Dor
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Cytochrome C ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Energy Transformation ◽  
Early Step ◽  
Electron Carrier ◽  
Stimulation Of

A preparation that contained cytochrome c, mainly in the form of its ‘dimer’, was studied and compared with native cytochrome c with respect to its ability to support electron transfer and energy transformation in cytochrome c-depleted rat liver mitochondria. When the depleted mitochondria were titrated with either cytochrome c or the ‘dimer’, the extent of coupling between respiration and phosphorylation was enhanced, as manifested by an increase in the P/O ratio. The ‘dimer’ was relatively ineffective as an electron carrier in the respiratory system, but it was as effective as cytochrome c in reconstitution of oxidative phosphorylation in depleted mitochondria. Addition of ‘dimer’ to the depleted mitochondria, in the presence of a low, non-saturating concentration of cytochrome c, increased the P/O ratio without concomitant stimulation of respiration. Both cytochrome c and the ‘dimer’ stimulated spontaneous swelling and electron transport-driven proton translocation in depleted mitochondria. The pattern of action of cytochrome c and its ‘dimer’ is in accord with the assumption that they affect an early step in energy conservation.

scholarly journals Carbon and Nitrogen Sources Have No Impact on the Organization and Composition of Ustilago maydis Respiratory Supercomplexes

2021 ◽  
Vol 7 (1) ◽  
pp. 42
Author(s):  
Deyamira Matuz-Mares ◽  
Oscar Flores-Herrera ◽  
Guadalupe Guerra-Sánchez ◽  
Lucero Romero-Aguilar ◽  
Héctor Vázquez-Meza ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Atp Synthesis ◽  
Nitrogen Sources ◽  
Growth Conditions ◽  
Energy Conditions ◽  
Respiratory Complexes ◽  
Respiratory Supercomplexes ◽  
Nadh Dehydrogenases ◽  
Reduced Nicotinamide Adenine Dinucleotide

Respiratory supercomplexes are found in mitochondria of eukaryotic cells and some bacteria. A hypothetical role of these supercomplexes is electron channeling, which in principle should increase the respiratory chain efficiency and ATP synthesis. In addition to the four classic respiratory complexes and the ATP synthase, U. maydis mitochondria contain three type II NADH dehydrogenases (NADH for reduced nicotinamide adenine dinucleotide) and the alternative oxidase. Changes in the composition of the respiratory supercomplexes due to energy requirements have been reported in certain organisms. In this study, we addressed the organization of the mitochondrial respiratory complexes in U. maydis under diverse energy conditions. Supercomplexes were obtained by solubilization of U. maydis mitochondria with digitonin and separated by blue native polyacrylamide gel electrophoresis (BN-PAGE). The molecular mass of supercomplexes and their probable stoichiometries were 1200 kDa (I1:IV1), 1400 kDa (I1:III2), 1600 kDa (I1:III2:IV1), and 1800 kDa (I1:III2:IV2). Concerning the ATP synthase, approximately half of the protein is present as a dimer and half as a monomer. The distribution of respiratory supercomplexes was the same in all growth conditions. We did not find evidence for the association of complex II and the alternative NADH dehydrogenases with other respiratory complexes.

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