Growth of Bacillus stearothermophilus on glycerol in chemostat culture: expression of an unusual phenotype

Burke, Ronald M.; Tempest, D. W.

doi:10.1099/00221287-136-7-1381

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…However, it is generally considered that gram-positive organisms do not synthesise glutathione (Fahey et al 1978), and the presence of the glyoxalase I-II pathway would require either an exogenous supply of glutathione or that this general statement be re-evaluated. Potassium-limited, glycerol-grown B. stearothermophilus excretes D-lactate and has enhanced levels of glyoxalase I-II enzymes as compared to glycerol-limited cultures (Burke and Tempest 1990). Staphylococcus aureus does not metabolise methylglyoxal even in the presence of glutathione.…”

Section: Reductases and Dehydrogenasesmentioning

confidence: 98%

“…The presence of methylglyoxal synthase in Bacillus stearothermophilus var. non-diastaticus has been demonstrated, and this organism has also evolved or acquired the glyoxalase I-II pathway (Tempest and Neijssel 1984;Burke and Tempest 1990), so at least for this organism a relatively conventional solution has been found. ORFs that could encode glyoxalase enzymes have been identified in B. subtilis (I. R. Booth, unpublished work).…”

Section: Reductases and Dehydrogenasesmentioning

confidence: 99%

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Methylglyoxal production in bacteria: suicide or survival?

Ferguson

Tötemeyer

MacLean

et al. 1998

Archives of Microbiology

230

259

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Methylglyoxal is a toxic electrophile. In Escherichia coli cells, the principal route of methylglyoxal production is from dihydroxyacetone phosphate by the action of methylglyoxal synthase. The toxicity of methylglyoxal is believed to be due to its ability to interact with the nucleophilic centres of macromolecules such as DNA. Bacteria possess an array of detoxification pathways for methylglyoxal. In E. coli, glutathione-based detoxification is central to survival of exposure to methylglyoxal. The glutathione-dependent glyoxalase I-II pathway is the primary route of methylglyoxal detoxification, and the glutathione conjugates formed can activate the KefB and KefC potassium channels. The activation of these channels leads to a lowering of the intracellular pH of the bacterial cell, which protects against the toxic effects of electrophiles. In addition to the KefB and KefC systems, E. coli cells are equipped with a number of independent protective mechanisms whose purpose appears to be directed at ensuring the integrity of the DNA. A model of how these protective mechanisms function will be presented. The production of methylglyoxal by cells is a paradox that can be resolved by assigning an important role in adaptation to conditions of nutrient imbalance. Analysis of a methylglyoxal synthase-deficient mutant provides evidence that methylglyoxal production is required to allow growth under certain environmental conditions. The production of methylglyoxal may represent a high-risk strategy that facilitates adaptation, but which on failure leads to cell death. New strategies for antibacterial therapy may be based on undermining the detoxification and defence mechanisms coupled with deregulation of methylglyoxal synthesis.

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Section: Reductases and Dehydrogenasesmentioning

confidence: 98%

Section: Reductases and Dehydrogenasesmentioning

confidence: 99%

Methylglyoxal production in bacteria: suicide or survival?

Ferguson

Tötemeyer

MacLean

et al. 1998

Archives of Microbiology

230

259

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“…phosphoglycerokinase and pyruvate kinase). It is known that B. stearothermophilus can synthesize enzymes of the methylglyoxal bypass under conditions where there is an overproduction of triose phosphates (Burke & Tempest, 1990), and if this bypass was functional it would cause a marked decrease in the ATP flux rate. Measurements of lactate dehydrogenase, methylglyoxal synthase and glyoxylase in cellfree extracts (Table 2) showed substantial activities of all three in cells that were oxygen-limited, activities that generally were higher than the rate of lactate formation in situ.…”

Section: Resultsmentioning

confidence: 99%

Metabolic response of Bacillus stearothermophilus chemostat cultures to a secondary oxygen limitation

Martins

Tempest

1991

Journal of General Microbiology

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With variously limited chemostat cultures of Bacillus stearothermophilus, the glucose consumption rate increased markedly as the concentration of dissolved oxygen (d.0.t.; dissolved oxygen tension) was lowered from 50% to 1 % air saturation. Concomitantly, the specific rate of acetate production increased and lactate, which was not present in the fully aerobic cultures, accumulated in large amounts. Moreover, whereas at a high d.0.t. only an ammonialimited culture excreted 2-oxoglutarate, all glucose-sufficient cultures excreted this metabolite at a d.0.t. of 1 % air saturation, even more being produced by a K+-limited culture than by the ammonia-limited one. The activities of those enzymes of glycolysis that were measured increased in parallel with the glucose consumption rate, as did the activities of enzymes of the Entner-Douderoff pathway. Similarly, the activities of lactate dehydrogenase and acetate kinase (which were synthesized constitutively also) reflected the corresponding metabolite production rates. Tricarboxylic acid (TCA) cycle activity markedly diminished with a lowering of the available oxygen supply and again (with the exception of aconitase and 2-oxoglutarate dehydrogenase) this was mirrored in decreases in the activities of TCA cycle enzymes. Assessments of energy flux in terms of ATP equivalents suggested that it was energetically more expensive to synthesize biomass at a low d.0.t. than at a high one. However, the presence of enzymes of the methylglyoxal bypass (methylglyoxal synthase and glyoxylase) at high activities in cells grown at a low d.0.t. render assessments of ATP flux rates unreliable.

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“…PCC 7002 is the only species known to utilize glycerol efficiently (Rippka et al, 1979). Glycerol metabolism in many organisms leads to an increase of cellular methylglyoxal, which is a toxic byproduct of carbon metabolism (Freedberg et al, 1971;Burke & Tempest, 1990;Russell & Cook, 1995). Methylglyoxal production has been found in nearly all cells.…”

Section: Discussionmentioning

confidence: 99%

Methylglyoxal detoxification by an aldo-keto reductase in the cyanobacterium Synechococcus sp. PCC 7002

Liu

Guo

et al. 2006

Microbiology

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Aldo-keto reductases (AKRs) are a superfamily of enzymes that reduce aldehydes and ketones, and have a broad range of substrates. An AKR gene, sakR1, was identified in the cyanobacterium Synechococcus sp. PCC 7002. A mutant strain with sakR1 inactivated was sensitive to glycerol, a carbon source that can support heterotrophic growth of Synechococcus sp. PCC 7002. It was found that the sakR1 null mutant accumulated more toxic methylglyoxal than the wild-type when glycerol was added to growth medium, suggesting that SakR1 is involved in the detoxification of methylglyoxal, a highly toxic metabolite that can damage cellular macromolecules. Enzymic analysis of recombinant SakR1 protein showed that it can efficiently reduce methylglyoxal with NADPH. Based on immunoblotting, SakR1 was not upregulated at an increased cellular methylglyoxal concentration. A pH-dependent enzyme-activity profile suggested that SakR1 activity could be regulated by cellular pH in Synechococcus sp. PCC 7002. The broad substrate specificity of SakR1 implies that SakR1 could play other roles in cellular metabolism. INTRODUCTIONCyanobacteria are a diverse group of prokaryotes that carry out oxygenic photosynthesis and grow photoautotrophically. Some cyanobacteria can also grow heterotrophically in the presence of organic substrates (Rippka et al., 1979). The substrates that support heterotrophic growth of cyanobacteria include the sugars fructose and glucose. However, in the cyanobacterium Synechococcus sp. PCC 7002, glycerol is the only substrate that supports heterotrophic growth. A high concentration of exogenous glycerol is inhibitory to cyanobacterial growth, and it has been observed that glycerol-dependent growth of Synechococcus sp. PCC 7002 is only established after a period of adaptation to glycerol.Although the pathway of glycerol metabolism has not been studied in cyanobacteria in detail, it is expected that it would be the same as that of other bacteria such as Escherichia coli, since, based on cyanobacterial genome sequences, cyanobacterial cells have all the genes to encode the enzymes required for glycerol metabolism (www.kazusa.or.jp/cyanobase; J. Zhao and D. A. Bryant, unpublished data). The inhibitory effect of glycerol to cyanobacterial growth could largely be due to toxic products of glycerol metabolism. One highly toxic product of cellular glycerol metabolism is methylglyoxal (Freedberg et al., 1971), which is an electrophile and reacts with cellular macromolecules such as proteins and DNA (Ferguson et al., 1998). One of the pathways leading to methylglyoxal production in most cells is the formation of methylglyoxal from dihydroxyacetone phosphate (DHAP) enzymically or non-enzymically (Ferguson et al., 1998;Kalapos, 1999). In most cells, detoxification of methylglyoxal is through glyoxalase I-II systems (Inoue & Kimmura, 1995;Kalapos, 1999). Another important mechanism is reduction of methylglyoxal by aldo-keto reductases (AKRs), which catalyse the formation of acetol from methylglyoxal (Kalapos, 1999).AKRs are a large supe...

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Growth of Bacillus stearothermophilus on glycerol in chemostat culture: expression of an unusual phenotype

Cited by 12 publications

References 14 publications

Methylglyoxal production in bacteria: suicide or survival?

Methylglyoxal production in bacteria: suicide or survival?

Metabolic response of Bacillus stearothermophilus chemostat cultures to a secondary oxygen limitation

Methylglyoxal detoxification by an aldo-keto reductase in the cyanobacterium Synechococcus sp. PCC 7002

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