Enzyme activities of <scp>D</scp>-glucose metabolism in the fission yeast <i>Schizosaccharomyces pombe</i>

Tsai, Chien-Sheng; Shi, Jiping; Beehler, B. W.; Beck, Bernd

doi:10.1139/m92-216

Cited by 11 publications

(9 citation statements)

References 36 publications

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“…This branch may short-circuit the OPP. However, we also demonstrated by activity assays the presence of two common enzymes of the glucose-phosphate branch, hexokinase (HK) and glucose-6-phosphate dehydrogenase (G6PDH), in the fission yeast culture (Tsai et al 1992). However, the identity of the glucose-phosphate branch and its enzymes in S. pombe has not been unequivocally established.…”

Section: Introductionmentioning

confidence: 88%

Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe

Tsai

Chen²

1998

Biochem. Cell Biol.

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Hexokinase and D-glucose-6-phosphate dehydrogenase (G6PDH) from Schizosaccharomyces pmbe have been purified 250-fold by an identical three-step. Both enzymes are dimeric with a molecular mass of 88 kDa for the kinase and 112 kDa for the dehydrogenase. Steady-state kinetic studies were performed on hexokinase and G6PDH, which form the glucose phosphate branch of the oxidative pentose phosphate pathway of S. pombe (fission yeast). Hexokinase promotes Mg(2+)-activated phosphorylation of D-glucose by the equilibrium random Bi Bi mechanism with formation of the abortive enzyme-ADP-glucose complex. ADP inhibits the kinase competitively versus ATP and noncompetitively versus D-glucose. The Mg2+ activation of hexokinase is associated with an increase in the maximal velocity by its interaction with the ternary complex to facilitate the transfer of the phosphoryl group. G6PDH catalyzes NADP(+)-linked oxidation of D-glucose-6-phosphate by the ordered Bi Bi mechanism with NADP+ as the leading reactant. High NADP+ concentration inhibits the dehydrogenase by forming the dead-end ternary complex. In addition, G6PDH is also subjected to product inhibition by NADPH and noncompetitive inhibition by A(G)TP. Thus, the oxidative pentose phosphate pathway in S. pombe may be regulated via inhibition of hexokinase by ADP in conjunction with inhibition of G6PDH by NADPH and ATP.

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Section: Introductionmentioning

confidence: 88%

Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe

Tsai

Chen²

1998

Biochem. Cell Biol.

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“…For Ght1p and Ght2p the kinetic transport analysis revealed moderate affinities to D-glucose, indicating that D-glucose is the preferred transport substrate, though this specificity does not exclude D-fructose from uptake. Discrimination between these two sugars takes place intracellularly: in S. pombe by D-fructosespecific hexokinase Hxk1 (K m of fructose ϭ 1.5 mM, K m of glucose ϭ 8.5 mM) (54,45) Because D-glucose transport properties of the S. pombe wildtype cells should be reflected correspondingly in the expression pattern of the involved genes, RNA expression of all Ght genes was monitored in cells grown on different carbon sources (Fig. 3).…”

Section: Fig 5 Expression Of Ght1mentioning

confidence: 99%

“…S. pombe cells can grow on the monosaccharide D-gluconate (23), whereas S. cerevisiae cells can utilize D-galactose and disaccharides such as sucrose (13,18). In contrast to S. cerevisiae, S. pombe can use ethanol but only in the presence of glucose (53,54). The narrow spectrum of carbon sources accepted by S. pombe is attributed to corresponding differences in carbon metabolism.…”

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confidence: 99%

Multiple Hexose Transporters ofSchizosaccharomyces pombe

et al. 2000

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We have identified a family of six hexose transporter genes (Ght1 to Ght6) in the fission yeast Schizosaccharomyces pombe. Sequence homology to Saccharomyces cerevisiae and mammalian hexose transporters (Hxtp and GLUTp, respectively) and secondary-structure predictions of 12 transmembrane domains for each of the Ght proteins place them into the sugar porter subfamily within the major facilitator superfamily. Interestingly, among this sugar porter family, the emerging S. pombe hexose transporter family clusters are separate from monosaccharide transporters of other yeasts (S. cerevisiae, Kluyveromyces lactis, and Candida albicans) and of humans, suggesting that these proteins form a distinct structural family of hexose transporters. Expression of the Ght1, Ght2, Ght5, and Ght6 genes in the S. cerevisiae mutant RE700A may functionally complement its D-glucose uptake-deficient phenotype. Northern blot analysis and reverse transcription-PCR showed that among all Ght's of S. pombe, Ght5 is the most prominently expressed hexose transporter. Ght1p, Ght2p, and Ght5p displayed significantly higher specificities for D-glucose than for D-fructose. Analysis of the previously described S. pombe D-glucose transport-deficient mutant YGS-5 revealed that this strain is defective in the Ght1, Ght5, and Ght6 genes. Based on an analysis of three S. pombe strains bearing single or double mutations in Ght3 and Ght4, we conclude that the Ght3p function is required for D-gluconate transport in S. pombe. The function of Ght4p remains to be clarified. Ght6p exhibited a slightly higher affinity to D-fructose than to D-glucose, and among the Ght's it is the transporter with the highest specificity for D-fructose.Hexose transporters comprise a family of proteins involved in cellular sugar uptake. They have been well described for a variety of organisms, including bacteria, yeasts, plants, and humans. Regarding sugar metabolism, the fission yeast Schizosaccharomyces pombe shares a number of characteristic properties with the budding yeast Saccharomyces cerevisiae. Both species grow as facultative aerobes and use aerobic alcoholic fermentation in the presence of an excess of sugar (17, 13). Among the utilized carbon sources, distinct differences are present. D-Glucose, D-fructose, glycerol, and maltose are metabolized by both yeast species, with D-glucose being the preferred substrate. S. pombe cells can grow on the monosaccharide D-gluconate (23), whereas S. cerevisiae cells can utilize D-galactose and disaccharides such as sucrose (13,18). In contrast to S. cerevisiae, S. pombe can use ethanol but only in the presence of glucose (53, 54). The narrow spectrum of carbon sources accepted by S. pombe is attributed to corresponding differences in carbon metabolism. The carbon metabolism of S. pombe does not involve the glyoxylate cycle, and furthermore, some enzymes of ethanol metabolism and gluconeogenesis are not constitutively expressed (53, 13).Considering transport into the cells as the first step of the utilization of sugar, both yeast spe...

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“…The presence of shunt pathway enzymes and their steady‐state levels in continuous cultures of fission yeast have been demonstrated earlier [12]. However, there have been no reports on the kinetics of synthesis of the shunt pathway enzymes.…”

Section: Introductionmentioning

confidence: 80%

Repression of enzymes of the pentose phosphate pathway by glucose in fission yeast

Mehta¹,

Velmurugan²,

Lobo³

1998

FEBS Letters

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We examine here the effect of carbon sources on the synthesis of the shunt pathway enzymes in the fission yeast Schizosaccharomyces pombe growing on a mixture of ethanol and glycerol. N N-Gluconolactone induces practically every one of these enzymes. Glucose in contrast tends to attenuate the synthesis of the majority of them. RNA analysis confirms that their induction and repression reflect changes in the levels of their transcripts.z 1998 Federation of European Biochemical Societies.

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Enzyme activities of D-glucose metabolism in the fission yeast Schizosaccharomyces pombe

Cited by 11 publications

References 36 publications

Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe

Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe

Multiple Hexose Transporters ofSchizosaccharomyces pombe

Repression of enzymes of the pentose phosphate pathway by glucose in fission yeast

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