Fructose-2,6-bisphosphate Activates Pyrophosphate:<scp>d</scp>-Fructose 6-Phosphate 1-Phosphotransferase from<i>Euglena gracilis</i>

Miyatake, Kazutaka; Enomoto, Toshiki; Kitaoka, Shôzaburô

doi:10.1080/00021369.1986.10867762

Cited by 5 publications

(4 citation statements)

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“…Two types of PP i -dependent phosphofructokinase activities have previously been reported in other cells. The first type has been detected mainly in higher plants (42) and Euglena gracilis (30) together with ATP-dependent phosphofructokinase activity and is regulated by fructose 2,6-bisphosphate (52). The second type is found in Amycolatopsis (1), Bacteroides (26,40), Entamoeba (39), Mycoplasma (36), Propionibacterium (2,34), Trichomonas (29), and Spirochaeta (17) species.…”

Section: Discussionmentioning

confidence: 99%

Phosphorylating enzymes involved in glucose fermentation of Actinomyces naeslundii

1995

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Enzymatic activities involved in glucose fermentation of Actinomyces naeslundii were studied with glucosegrown cells from batch cultures. Glucose could be phosphorylated to glucose 6-phosphate by a glucokinase that utilized polyphosphate and GTP instead of ATP as a phosphoryl donor. Glucose 6-phosphate was further metabolized to the end products lactate, formate, acetate, and succinate through the Embden-Meyerhof-Parnas pathway. The phosphoryl donor for phosphofructokinase was only PP i . Phosphoglycerate kinase, pyruvate kinase, and acetate kinase coupled GDP as well as ADP, but P i compounds were not their phosphoryl acceptor. Cell extracts showed GDP-dependent activity of phosphoenolpyruvate carboxykinase, which assimilates bicarbonate and phosphoenolpyruvate into oxaloacetate, a precursor of succinate. Considerable amounts of GTP, polyphosphate, and PP i were found in glucose-fermenting cells, indicating that these compounds may serve as phosphoryl donors or acceptors in Actinomyces cells. PP i could be generated from UTP and glucose 1-phosphate through catalysis of UDP-glucose synthase, which provides UDP-glucose, a precursor of glycogen.Actinomyces naeslundii (formerly A. naeslundii and Actinomyces viscosus [18]) is one of the predominant bacteria in the oral microflora (10, 12). These bacteria are among the pioneer microbial species on tooth surfaces (28) and have been implicated in oral diseases, such as dental caries (3,11,45) and gingivitis (25,31,32). Actinomyces cells metabolize carbohydrates to organic acids and can also accumulate intracellular polysaccharides. These properties are considered to be related to the cariogenic potential of these bacteria (22).Although carbohydrates are a main energy source, only limited information is available on their metabolism by A. naeslundii. Since the studies of Buchanan and Pine (5), it was generally accepted that Actinomyces cells degrade carbohydrates through the Embden-Meyerhof-Parnas pathway and can also assimilate bicarbonate into oxaloacetate, a precursor for succinate formation in this bacterial genus (4,47,48).In a recent study on the initial sorbitol catabolism by some selected oral isolates of A. naeslundii (20), we found that these bacteria had a hexokinase activity that catalyzed the phosphorylation of fructose to fructose 6-phosphate in the presence of GTP. The enzyme activity appeared essential for sorbitol metabolism by these strains since they lacked a phosphotransferase system for sorbitol (20). These findings prompted us to further study the metabolism of glucose by Actinomyces cells, especially the activities of enzymes involved in energy turnover. MATERIALS AND METHODS Permeabilized cells and cell extracts.A. naeslundii genospecies 1 ATCC 12104 and WVU 398A, A. naeslundii genospecies 2 WVU 627 and W1053, and A. viscosus ATCC 15987 were used. Strain ATCC 15987 was isolated from the mouth of a hamster, while the other strains are isolates from humans (18). Bacteria were grown in a phyton-peptone-based culture medium supplemented with 0.2% glu...

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Section: Discussionmentioning

confidence: 99%

Phosphorylating enzymes involved in glucose fermentation of Actinomyces naeslundii

1995

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“…It was subsequently found in the bacterium Propionibacterium shermanii, in the photosynthetic protist Euglena gracilis [3], and in much more evolved higher plants [4]. More recently, PPi-PFK was detected in Isotrichaprostoma (a ciliate living in the rumen [5]), in the parasitic flagellates…”

Section: Ppi-pfk Among the Living Organismsmentioning

confidence: 98%

Pyrophosphate‐dependent phosphofructokinase, an anaerobic glycolytic enzyme?

1991

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Recent evidence indicates that in as diverse organisms as unicellular eukaryotes, higher plants and prokaryotes, anaerobic glycolysis relies on a pyrophosphate-dependent phosphofructokinase instead of the classical ATP-dependent enzyme. This difference in phosphoryl donor specificity does not necessarily reflect a primitive metabolism, as thought earlier, but could rather be the result of convergent evolution, fostered by the energetic advantage conferred to the cell when glycolysis is the sole source of ATP.

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“…The activity of PPi-PFK was 10-30 times higher than that of ATP-PFK throughout cell growth. Euglena PPi-PFK activity was highly regulated by fructose 2,6-bisphosphate (F26BP) which is known to be a potent activator of mammalian ATP-PFK and plant PPi-PFK (Enomoto et al 1988;Miyatake et al 1986). In the forward reaction, the saturation curve for fructose 6-phosphate was sigmoidal and the apparent K 0.5 value was 2.5 mM.…”

Section: The Glycolytic Pathway and Its Regulationmentioning

confidence: 99%

Wax Ester Fermentation and Its Application for Biofuel Production

Inui

Ishikawa

Tamoi

2017

Advances in Experimental Medicine and Biology

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In Euglena cells under anaerobic conditions, paramylon, the storage polysaccharide, is promptly degraded and converted to wax esters. The wax esters synthesized are composed of saturated fatty acids and alcohols with chain lengths of 10-18, and the major constituents are myristic acid and myristyl alcohol. Since the anaerobic cells gain ATP through the conversion of paramylon to wax esters, the phenomenon is named "wax ester fermentation". The wax ester fermentation is quite unique in that the end products, i.e. wax esters, have relatively high molecular weights, are insoluble in water, and accumulate in the cells, in contrast to the common fermentation end products such as lactic acid and ethanol.A unique metabolic pathway involved in the wax ester fermentation is the mitochondrial fatty acid synthetic system. In this system, fatty acid are synthesized by the reversal of β-oxidation with an exception that trans-2-enoyl-CoA reductase functions instead of acyl-CoA dehydrogenase. Therefore, acetyl-CoA is directly used as a C donor in this fatty acid synthesis, and the conversion of acetyl-CoA to malonyl-CoA, which requires ATP, is not necessary. Consequently, the mitochondrial fatty acid synthetic system makes possible the net gain of ATP through the synthesis of wax esters from paramylon. In addition, acetyl-CoA is provided in the anaerobic cells from pyruvate by the action of a unique enzyme, oxygen sensitive pyruvate:NADP oxidoreductase, instead of the common pyruvate dehydrogenase multienzyme complex.Wax esters produced by anaerobic Euglena are promising biofuels because myristic acid (C) in contrast to other algal produced fatty acids, such as palmitic acid (C) and stearic acid (C), has a low freezing point making it suitable as a drop-in jet fuel. To improve wax ester production, the molecular mechanisms by which wax ester fermentation is regulated in response to aerobic and anaerobic conditions have been gradually elucidated by identifying individual genes related to the wax ester fermentation metabolic pathway and by comprehensive gene/protein expression analysis. In addition, expression of the cyanobacterial Calvin cycle fructose-1,6-bisphosphatase/sedohepturose-1,7-bisphosphatase, in Euglena provided photosynthesis resulting in increased paramylon accumulation enhancing wax ester production. This chapter will discuss the biochemistry of the wax ester fermentation, recent advances in our understanding of the regulation of the wax ester fermentation and genetic engineering approaches to increase production of wax esters for biofuels.

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Fructose-2,6-bisphosphate Activates Pyrophosphate:d-Fructose 6-Phosphate 1-Phosphotransferase fromEuglena gracilis

Cited by 5 publications

References 6 publications

Phosphorylating enzymes involved in glucose fermentation of Actinomyces naeslundii

Phosphorylating enzymes involved in glucose fermentation of Actinomyces naeslundii

Pyrophosphate‐dependent phosphofructokinase, an anaerobic glycolytic enzyme?

Wax Ester Fermentation and Its Application for Biofuel Production

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