Inhibition of oxidative metabolism in Escherichia coli by d-camphor and restoration of oxidase activity by quinones

Oxidative metabolism in whole cells of Escherichia coli strain 82/r was inhibited by d-camphor when glucose, pyruvate, or succinate was used as substrate. Inhibition was not due to lower surface tension in d-camphor-treated cell suspensions nor was it a function of cell permeability. Succinic, lactic, and NADH-oxidase activities were inhibited in alumina powder cell-free extracts (80 μg of protein/ml) by d-camphor (1100 μg/ml). NADH: and succinic: DCPIP oxidoreductase enzymes were unaffected by d-camphor. Menadione (vitamin K3) restored succinic, lactic, and NADH-oxidase activities in d-camphor-inhibited cell-free extracts. Concentrations of menadione used to restore succinic and NADH oxidase activities were not stimulatory in non-camphor-treated extracts. Succinic oxidase activity in d-camphor-inhibited cell-free extracts was also restored by ubiquinone (Q6) but not by vitamin K1. These results are interpreted to indicate that d-camphor may affect quinone function in E. coli.

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High Glycolytic Flux Improves Pyruvate Production by a Metabolically Engineered Escherichia coli Strain

Applied and Environmental Microbiology ◽

10.1128/aem.01610-08 ◽

2008 ◽

Vol 74 (21) ◽

pp. 6649-6655 ◽

Cited By ~ 61

Author(s):

Yihui Zhu ◽

Mark A. Eiteman ◽

Ronni Altman ◽

Elliot Altman

Keyword(s):

Escherichia Coli ◽

Nadh Oxidase ◽

Pyruvate Dehydrogenase Complex ◽

Formation Rate ◽

Batch Process ◽

Defined Medium ◽

Coli Strain ◽

Glycolytic Flux ◽

Exponential Feeding ◽

Phosphoenolpyruvate Synthase

ABSTRACT We report pyruvate formation in Escherichia coli strain ALS929 containing mutations in the aceEF, pfl, poxB, pps, and ldhA genes which encode, respectively, the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, phosphoenolpyruvate synthase, and lactate dehydrogenase. The glycolytic rate and pyruvate productivity were compared using glucose-, acetate-, nitrogen-, or phosphorus-limited chemostats at a growth rate of 0.15 h−1. Of these four nutrient limitation conditions, growth under acetate limitation resulted in the highest glycolytic flux (1.60 g/g ï¿½ h), pyruvate formation rate (1.11 g/g ï¿½ h), and pyruvate yield (0.70 g/g). Additional mutations in atpFH and arcA (strain ALS1059) further elevated the steady-state glycolytic flux to 2.38 g/g ï¿½ h in an acetate-limited chemostat, with heterologous NADH oxidase expression causing only modest additional improvement. A fed-batch process with strain ALS1059 using defined medium with 5 mM betaine as osmoprotectant and an exponential feeding rate of 0.15 h−1 achieved 90 g/liter pyruvate, with an overall productivity of 2.1 g/liter ï¿½ h and yield of 0.68 g/g.

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Synthesis and in Silico Modelling of the Potential Dual Mechanistic Activity of Small Cationic Peptides Potentiating the Antibiotic Novobiocin against Susceptible and Multi-Drug Resistant Escherichia coli

International Journal of Molecular Sciences ◽

10.3390/ijms21239134 ◽

2020 ◽

Vol 21 (23) ◽

pp. 9134

Author(s):

Ilaria Passarini ◽

Pedro Ernesto de Resende ◽

Sarah Soares ◽

Tadeh Tahmasi ◽

Paul Stapleton ◽

...

Keyword(s):

Escherichia Coli ◽

In Silico ◽

Mammalian Cells ◽

Antimicrobial Agents ◽

Efflux Pump ◽

Coli Strain ◽

Cell Permeability ◽

Cationic Peptides ◽

Drug Resistant ◽

E Coli

Cationic antimicrobial peptides have attracted interest, both as antimicrobial agents and for their ability to increase cell permeability to potentiate other antibiotics. However, toxicity to mammalian cells and complexity have hindered development for clinical use. We present the design and synthesis of very short cationic peptides (3–9 residues) with potential dual bacterial membrane permeation and efflux pump inhibition functionality. Peptides were designed based upon in silico similarity to known active peptides and efflux pump inhibitors. A number of these peptides potentiate the activity of the antibiotic novobiocin against susceptible Escherichia coli and restore antibiotic activity against a multi-drug resistant E. coli strain, despite having minimal or no intrinsic antimicrobial activity. Molecular modelling studies, via docking studies and short molecular dynamics simulations, indicate two potential mechanisms of potentiating activity; increasing antibiotic cell permeation via complexation with novobiocin to enable self-promoted uptake, and binding the E. coli RND efflux pump. These peptides demonstrate potential for restoring the activity of hydrophobic drugs.

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RESPIRATION AND PROTEIN SYNTHESIS IN ESCHERICHIA COLI MEMBRANE-ENVELOPE FRAGMENTS

The Journal of Cell Biology ◽

10.1083/jcb.55.2.266 ◽

1972 ◽

Vol 55 (2) ◽

pp. 266-281 ◽

Cited By ~ 14

Author(s):

Richard W. Hendler ◽

Amelia H. Burgess

Keyword(s):

Escherichia Coli ◽

Nicotinamide Adenine Dinucleotide ◽

Oxidase Activity ◽

Nadh Oxidase ◽

Molecular Size ◽

Reduced Form ◽

Lactate Oxidase ◽

Membrane Envelope ◽

Nadh Oxidase Activity ◽

Sepharose 4B

Membranes obtained from Escherichia coli have been solubilized with deoxycholate. The solubilized dehydrogenases and cytochromes are not sedimented at 105,000 g. These components readily penetrate the "included space" of Sepharose 4B (Pharmacia Fine Chemicals Inc., Uppsala, Sweden) and polyacrylamide gels and have been fractionated on the basis of molecular size. Solubilization destroys nicotinamide adenine dinucleotide, reduced form (NADH) oxidase and D-lactate oxidase activities, but leaves an appreciable part of the original succinoxidase activity intact. Evidence for a succinate dehydrogenase-cytochrome b1 complex is given. Menadione added to the solubilized preparation does not elicit NADH oxidase activity nor stimulate the existing succinoxidase activity, but does provoke an active D-lactate oxidase activity. This D-lactate oxidase activity, however, does not use cytochromes and is not sensitive to cyanide.

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