scholarly journals RESPIRATION AND PROTEIN SYNTHESIS IN ESCHERICHIA COLI MEMBRANE-ENVELOPE FRAGMENTS

1970 ◽  
Vol 46 (1) ◽  
pp. 114-129 ◽  
Author(s):  
Richard W. Hendler ◽  
N. Nanninga
Keyword(s):  
Escherichia Coli ◽  
Carbon Monoxide ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Wave Length ◽  
Spectrophotometric Analysis ◽  
Difference Spectra ◽  
Absorption Bands ◽  
Optical Extinction ◽  
Transport Chain

The membranous nature of pellets obtained from broken Escherichia coli spheroplasts by successive centrifugation at 3500 g (P1), 20,000 g (P2), and 105,000 g (P3), has been established by electron microscopy. Spectrophotometric analysis has shown that about 90% of the cytochromes are concentrated in the particulate fractions. The crude ribosomal pellet (P3) contained as much of the total cytochromes as did the pellet obtained at 20,000 g (P2). The high cytochrome content of P3 is consistent with its high oxidative activity (1) and the presence of membrane vesicles in this fraction. Analysis at 77°K intensified the optical extinction of all the cytochrome absorption bands, but the degree of intensification was not uniform for each fraction nor for each band within a given fraction. Carbon monoxide had little or no inhibiting effect on NADH oxidation. Reduced plus carbon monoxide difference spectra yielded artifactual absorption bands in the wave length regions where reduced vs. oxidized absorption bands normally occur. Succinate and NADH, either together or separately, reduced nearly all of the cytochromes, indicating that the cytochrome portion of the electron-transport chain is shared by both substrates. A tentative formulation of the electron-transport chain is presented.

scholarly journals The oxidation of nicotinic acid by Pseudomonas ovalis Chester. The terminal oxidase

1972 ◽  
Vol 129 (3) ◽  
pp. 755-761 ◽  
Author(s):  
M. V. Jones ◽  
D. E. Hughes
Keyword(s):  
Electron Transport ◽  
Nicotinic Acid ◽  
Electron Transport Chain ◽  
Acid Oxidase ◽  
Terminal Oxidase ◽  
Difference Spectra ◽  
Terminal Oxidases ◽  
Cytochrome O ◽  
Transport Chain ◽  
Terminal Oxidation

In cell-free extracts of Pseudomonas ovalis nicotinic acid oxidase is confined to the wallmembrane fraction. It is associated with an electron-transport chain comprising b- and c-type cytochromes only, differing proportions of which are reduced by nicotinate and NADH. CO difference-spectra show two CO-binding pigments, cytochrome o (absorption maximum at 417nm) and another component absorbing maximally at 425nm. Cytochrome o is not reduced by NADH or by succinate but is by nicotinate, which can also reduce the ‘425’ CO-binding pigment. The effects of inhibitors of terminal oxidation support the idea of two terminal oxidases and a scheme involving the ‘425’ CO-binding pigment and the other components of the electron-transport chain is proposed.

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 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.

Growth-inhibitory activities of some 1,4-naphthoquinones and related compounds on Staphylococcus aureus and Escherichia coli

1968 ◽  
Vol 14 (6) ◽  
pp. 661-666 ◽  
Author(s):  
G. J. Leahy ◽  
D. J Currie ◽  
H. L. Holmes ◽  
J. R. Maltman
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Growth Inhibitory ◽  
Transport Chain ◽  
Half Wave ◽  
Inhibitory Activities ◽  
Related Compounds

Growth-inhibitory activities of some or all of 98 1,4-naphthoquinones and 16 related compounds on Escherichia coli and two strains of Staphylococcus aureus were determined alone or in combination. These values, when plotted against their polarographic half-wave potentials and those of their C2-n-butylthio analogs support the hypothesis that these compounds, or the products resulting from their reaction with a protein nucleophile, function by short-circuiting one or other of the quinones present in the electron-transport chain.

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