The role of xylulokinase in Saccharomyces cerevisiae xylulose catabolism

Richard, Peter

doi:10.1016/s0378-1097(00)00312-8

Cited by 40 publications

(59 citation statements)

References 18 publications

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“…Compared to other sugar kinases like ribulokinase (Lee et al, 2001), XK shows stronger substrate specificities in S. cerevisiae (Richard et al, 2000) or in E. coli (Wungsintaweekul, 2001). Nevertheless, the enzyme accepts DX as a substrate.…”

Section: Discussionmentioning

confidence: 99%

A Cytosolic Arabidopsis d-Xylulose Kinase Catalyzes the Phosphorylation of 1-Deoxy-d-Xylulose into a Precursor of the Plastidial Isoprenoid Pathway

et al. 2006

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Plants are able to integrate exogenous 1-deoxy-D-xylulose (DX) into the 2C-methyl-D-erythritol 4-phosphate pathway, implicated in the biosynthesis of plastidial isoprenoids. Thus, the carbohydrate needs to be phosphorylated into 1-deoxy-D-xylulose 5-phosphate and translocated into plastids, or vice versa. An enzyme capable of phosphorylating DX was partially purified from a cell-free Arabidopsis (Arabidopsis thaliana) protein extract. It was identified by mass spectrometry as a cytosolic protein bearing D-xylulose kinase (XK) signatures, already suggesting that DX is phosphorylated within the cytosol prior to translocation into the plastids. The corresponding cDNA was isolated and enzymatic properties of a recombinant protein were determined. In Arabidopsis, xylulose kinases are encoded by a small gene family, in which only two genes are putatively annotated. The additional gene is coding for a protein targeted to plastids, as was proved by colocalization experiments using green fluorescent protein fusion constructs. Functional complementation assays in an Escherichia coli strain deleted in XK revealed that the cytosolic enzyme could exclusively phosphorylate xylulose in vivo, not the enzyme that is targeted to plastids. XK activities could not be detected in chloroplast protein extracts or in proteins isolated from its ancestral relative Synechocystis sp. PCC 6803. The gene encoding the plastidic protein annotated as ''xylulose kinase'' might in fact yield an enzyme having different phosphorylation specificities. The biochemical characterization and complementation experiments with DX of specific Arabidopsis knockout mutants seedlings treated with oxo-clomazone, an inhibitor of 1-deoxy-D-xylulose 5-phosphate synthase, further confirmed that the cytosolic protein is responsible for the phosphorylation of DX in planta.In plants, the biosynthesis of the active isoprene units (D 2 -and D 3

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Section: Discussionmentioning

confidence: 99%

A Cytosolic Arabidopsis d-Xylulose Kinase Catalyzes the Phosphorylation of 1-Deoxy-d-Xylulose into a Precursor of the Plastidial Isoprenoid Pathway

et al. 2006

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“…Despite the inherent redox constraints of S. cerevisiae strains based on the xylose reductase/xylitol dehydrogenase strategy, this strategy has resulted in many important insights into the kinetics of d-xylose metabolism by engineered S. cerevisiae strains. These findings include the benefits of overexpression of xylulokinase [29,56], the side role of the S. cerevisiae aldose reductase (Gre3) (besides the heterologous dual specificity xylose reductases) in xylitol formation [66], the role of the enzymes of the non-oxidative part of the pentose phosphate pathway [34,43], characterisation of d-xylose transport [27,62] and many studies on the inhibitor tolerance/sensitivity of d-xylose-consuming strains [54]. The latter will be especially crucial for successful application of d-xylose-consuming S. cerevisiae strains for ethanol production from lignocellulosic hydrolysates (see Sect.…”

Section: Introduction Of Heterologous Genes Encoding Xylose Reductasementioning

confidence: 99%

Development of Efficient Xylose Fermentation in Saccharomyces cerevisiae: Xylose Isomerase as a Key Component

Maris

Winkler

Kuyper

et al. 2007

Advances in Biochemical Engineering/Biotechnology

169

160

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“…These cultivation conditions are close to the ones prevailing during the batch cultivation of CPB.CR5. Therefore, one can assume that intracellular ATP concentration in CPB.CR5 is below 1.78 mM, since both XK and GS-GOGAT are overexpressed, and even below the affinity of ATP for XK, which has been reported to be around 1.5 mM (11). Hence, XK cannot operate efficiently, and xylulose phosphorylation is not sufficient to make the downstream conversion of xylitol favorable (thermodynamics of XR and XDH favor formation of xylitol) (12,13).…”

Section: Discussionmentioning

confidence: 99%

Metabolic Engineering of Ammonium Assimilation in Xylose-Fermenting Saccharomyces cerevisiae Improves Ethanol Production

Roca

Nielsen

Olsson

2003

Appl Environ Microbiol

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Cofactor imbalance impedes xylose assimilation in Saccharomyces cerevisiae that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant S. cerevisiae by deleting GDH1, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either GDH2, which encodes an NADH-dependent glutamate dehydrogenase, or GLT1 and GLN1, which encode the GS-GOGAT complex. Overexpression of GDH2 increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol ؊1 , mainly by reducing xylitol excretion by 44%. Overexpression of the GS-GOGAT complex did not improve conversion of xylose to ethanol during batch cultivation, but it increased ethanol yield by 16% in carbon-limited continuous cultivation at a low dilution rate.In order to develop an efficient process for the production of bioethanol from lignocellulosic material, there have been many attempts to improve the conversion of xylose to ethanol by construction of recombinant Saccharomyces cerevisiae strains.Even though the open reading frames encoding the three first enzymes involved in xylose metabolism, i.e., xylose reductase (XR), xylitol dehydrogenase (XDH), and xylulose kinase (XK), have been identified in the genome of S. cerevisiae (10, 15), the genes are poorly expressed (or not expressed at all), and xylose cannot be metabolized without introduction of heterologous genes from naturally xylose-fermenting microorganisms and overexpression of endogenous XK (3,6,17). In the resulting strains, there is a low rate of xylose consumption and substantial xylitol secretion.Since xylose-metabolizing strains of S. cerevisiae harbor a NAD(P)H-dependent xylose reductase and a NAD ϩ -dependent xylitol dehydrogenase from Pichia stipitis, one of the main reasons for xylitol excretion can be explained by the redox imbalance occurring at the level of XR and XDH. Metabolic engineering of redox metabolism may therefore be a strategy for improving the conversion of xylose to ethanol. This has been illustrated by deletion of the zwf1 gene encoding glucose-6-phosphate dehydrogenase in a xylose-metabolizing strain of S. cerevisiae (7). The main source of NADPH originating from the oxidative part of the pentose phosphate pathway has thereby been reduced, and during growth on xylose, this has resulted in a significant improvement of ethanol yield, from 0.31 g g Ϫ1 (yield on consumed sugar) to 0.41 g g Ϫ1 with a concomitant reduction in the xylitol yield.In this study, we have taken a different approach to modulating the redox metabolism to favor xylose metabolism, namely through metabolic engineering of the ammonia assimilation. Ammonium assimilation in S. cerevisiae involves glutamate dehydrogenase and glutamine synthetase. Glutamate dehydrogenase catalyzes the synthesis of glutamate from ammonium and 2-ketoglutarate. The most important enzyme for ammonia assimilation is the NADPH-dependent glutamate dehydrogenase 1, encoded by GDH1. The other glutamate dehydrogenase that is present in S. cerevisiae is N...

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The role of xylulokinase in Saccharomyces cerevisiae xylulose catabolism

Cited by 40 publications

References 18 publications

A Cytosolic Arabidopsis d-Xylulose Kinase Catalyzes the Phosphorylation of 1-Deoxy-d-Xylulose into a Precursor of the Plastidial Isoprenoid Pathway

A Cytosolic Arabidopsis d-Xylulose Kinase Catalyzes the Phosphorylation of 1-Deoxy-d-Xylulose into a Precursor of the Plastidial Isoprenoid Pathway

Development of Efficient Xylose Fermentation in Saccharomyces cerevisiae: Xylose Isomerase as a Key Component

Metabolic Engineering of Ammonium Assimilation in Xylose-Fermenting Saccharomyces cerevisiae Improves Ethanol Production

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