From famine to feast: the role of methylglyoxal production in <i>Escherichia coli</i>

Tötemeyer, Sabine; Booth, Nuala A.; Nichols, Wright W.; Dunbar, Bryan; Booth, Ian R.

doi:10.1046/j.1365-2958.1998.00700.x

Cited by 126 publications

(125 citation statements)

References 44 publications

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“…The ability to withstand the toxic effects of MG is influenced by the permeability of the membrane, the capacity for DNA repair, and the levels of detoxification enzymes (Ferguson et al, 1995). MG is produced in E. coli from DHAP via the enzyme MG synthase (MGS), encoded by the mgsA gene (Totemeyer et al, 1998). It is well known that the mechanism the cells use to cope with MG toxicity involves decreasing the intracellular pH.…”

Section: Inability To Ferment Glycerol At Basic Ph: Co 2 Availabilitymentioning

confidence: 99%

Anaerobic fermentation of glycerol byEscherichia coli: A new platform for metabolic engineering

Dharmadi

Murarka

González

2006

Biotechnol. Bioeng.

376

303

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The worldwide surplus of glycerol generated as inevitable byproduct of biodiesel fuel and oleochemical production is resulting in the shutdown of traditional glycerol-producing/refining plants and new applications are needed for this now abundant carbon source. In this article we report our finding that Escherichia coli can ferment glycerol in a pH-dependent manner. We hypothesize that glycerol fermentation is linked to the availability of CO 2 , which under acidic conditions is produced by the oxidation of formate by the enzyme formate hydrogen lyase (FHL). In agreement with this hypothesis, glycerol fermentation was severely impaired by blocking the activity of FHL. We demonstrated that, unlike CO 2 , hydrogen (the other product of FHL-mediated formate oxidation) had a negative impact on cell growth and glycerol fermentation. In addition, supplementation of the medium with CO 2 partially restored the ability of an FHL-deficient strain to ferment glycerol. High pH resulted in low CO 2 generation (low activity of FHL) and availability (most CO 2 is converted to bicarbonate), and consequently very inefficient fermentation of glycerol. Most of the fermented glycerol was recovered in the reduced compounds ethanol and succinate (93% of the product mixture), which reflects the highly reduced state of glycerol and confirms the fermentative nature of this process. Since glycerol is a cheap, abundant, and highly reduced carbon source, our findings should enable the development of an E. coli-based platform for the anaerobic production of reduced chemicals from glycerol at yields higher than those obtained from common sugars, such as glucose. ß

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Section: Inability To Ferment Glycerol At Basic Ph: Co 2 Availabilitymentioning

confidence: 99%

Anaerobic fermentation of glycerol byEscherichia coli: A new platform for metabolic engineering

Dharmadi

Murarka

González

2006

Biotechnol. Bioeng.

376

303

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“…Bacteria produce electrophiles themselves as metabolic by-products when they are unable to regulate carbon influx (39). In addition, pathogens may become exposed to electrophiles from exogenous sources (e.g., during entry into macrophages [10]).…”

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confidence: 99%

KefF, the Regulatory Subunit of the Potassium Efflux System KefC, Shows Quinone Oxidoreductase Activity

et al. 2011

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Escherichia coli and many other Gram-negative pathogenic bacteria protect themselves from the toxic effects of electrophilic compounds by using a potassium efflux system (Kef). Potassium efflux is coupled to the influx of protons, which lowers the internal pH and results in immediate protection. The activity of the Kef system is subject to complex regulation by glutathione and its S conjugates. Full activation of KefC requires a soluble ancillary protein, KefF. This protein has structural similarities to oxidoreductases, including human quinone reductases 1 and 2. Here, we show that KefF has enzymatic activity as an oxidoreductase, in addition to its role as the KefC activator. It accepts NADH and NADPH as electron donors and quinones and ferricyanide (in addition to other compounds) as acceptors. However, typical electrophilic activators of the Kef system, e.g., N-ethyl maleimide, are not substrates. If the enzymatic activity is disrupted by site-directed mutagenesis while retaining structural integrity, KefF is still able to activate the Kef system, showing that the role as an activator is independent of the enzyme activity. Potassium efflux assays show that electrophilic quinones are able to activate the Kef system by forming S conjugates with glutathione. Therefore, it appears that the enzymatic activity of KefF diminishes the redox toxicity of quinones, in parallel with the protection afforded by activation of the Kef system.

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“…Intracellular levels of these phosphorylated compounds might be regulated by an appropriate level of glycolysis. A disturbance of glycolytic metabolism by an externally added phosphorylated sugar was shown to cause cell death with a production of methylglyoxal (MG), a toxic by-product generated from dihydroxyacetone phosphate (20). However, MG production was observed for only a subset of sugar phosphates which enter directly into the glycolytic pathway, including D-glucose 6-phosphate, D-fructose 6-phosphate, and D-mannose 6-phosphate (8).…”

mentioning

confidence: 99%

Ribose Utilization with an Excess of Mutarotase Causes Cell Death Due to Accumulation of Methylglyoxal

Kim

Yoo

et al. 2004

J Bacteriol

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Methylglyoxal (MG) is a highly reactive metabolic intermediate, presumably accumulated during uncontrolled carbohydrate metabolism. The major source of MG is dihydroxyacetone phosphate, which is catalyzed by MG synthase (the mgs product) in bacteria. We observed Escherichia coli cell death when the ribose transport system, consisting of the RbsDACBK proteins, was overproduced on multicopy plasmids. Almost 100% of cell death occurs a few hours after ribose addition (>10 mM), due to an accumulation of extracellular MG as detected by 1 H-nuclear magnetic resonance ( 1 H-NMR). Under lethal conditions, the concentration of MG produced in the medium reached approximately 1 mM after 4 h of ribose addition as measured by high-performance liquid chromatography. An excess of the protein RbsD, recently characterized as a mutarotase that catalyzes the conversion between the ␤-pyran and ␤-furan forms of ribose, was critical in accumulating the lethal level of MG, which was also shown to require ribokinase (RbsK). The intracellular level of ribose 5-phosphate increased with the presence of the protein RbsD, as determined by 31 P-NMR. As expected, a mutation in the methylglyoxal synthase gene (mgs) abolished the production of MG. These results indicate that the enhanced ribose uptake and incorporation lead to an accumulation of MG, perhaps occurring via the pentose-phosphate pathway and via glycolysis with the intermediates fructose 6-phosphate and glyceraldehyde 3-phosphate. It was also demonstrated that a small amount of MG is synthesized by monoamine oxidase.

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From famine to feast: the role of methylglyoxal production in Escherichia coli

Cited by 126 publications

References 44 publications

Anaerobic fermentation of glycerol byEscherichia coli: A new platform for metabolic engineering

Anaerobic fermentation of glycerol byEscherichia coli: A new platform for metabolic engineering

KefF, the Regulatory Subunit of the Potassium Efflux System KefC, Shows Quinone Oxidoreductase Activity

Ribose Utilization with an Excess of Mutarotase Causes Cell Death Due to Accumulation of Methylglyoxal

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