[119] l-glutamate dehydrogenases (yeast)

Doherty, Delma

doi:10.1016/0076-6879(71)17294-1

Cited by 81 publications

(50 citation statements)

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“…Shikimate dehydrogenase (Shikimate:NADP + oxidoreductase, EC 1.1.1.25) was assayed in the reverse direction as described in [16]. Glutamate dehydrogenase (Lglutamate:NADP + oxidoreductase [transaminating], EC 1.4.1.13) was assayed as described in [17], monitoring the conversion of ~-ketoglutarate to glutamate. Specific activity is in izmol -~ .min -~ .mg -~.…”

Section: Enzyme Assaysmentioning

confidence: 99%

The Saccharomyces cerevisiae ARO1 gene An example of the co‐ordinate regulation of five enzymes on a single biosynthetic pathway

Duncan

Edwards²,

Coggins

1988

FEBS Letters

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The ARO1 gene of Saccharomyces cerevisiae encodes the arom multifunctional enzyme. Specific inhibitors of amino acid biosynthesis have been used to obtain evidence that expression of a cloned ARO1 gene is regulated in response to amino acid limitation. Northern blot analysis and sequence studies indicate that ARO1 is regulated by the well characterised S. cerevisiae 'general control' mechanism. This provides a very economical means of simultaneously tailoring the synthesis of five shikimate pathway enzymes to the needs of the cell.

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Section: Enzyme Assaysmentioning

confidence: 99%

The Saccharomyces cerevisiae ARO1 gene An example of the co‐ordinate regulation of five enzymes on a single biosynthetic pathway

Duncan

Edwards²,

Coggins

1988

FEBS Letters

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“…NADP-GDH and NAD-GDH were assayed by the method of Doherty (23). One unit of activity is defined as the oxidation of 1.0 mol of NADPH or NADH/min.…”

Section: Enzyme Assay and Protein Determinationmentioning

confidence: 99%

“…Cells were harvested at an optical density of 0.8 -1.0 at 600 nm and stored at Ϫ70°C until used. NADP-GDH was purified by a modified version of the method of Doherty (23). All steps were carried out at 5°C.…”

Section: Nadp-gdh Purificationmentioning

confidence: 99%

NADP-Glutamate Dehydrogenase Isoenzymes of Saccharomyces cerevisiae

DeLuna¹,

Avendaño

Riego

et al. 2001

Journal of Biological Chemistry

141

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In the yeast Saccharomyces cerevisiae, two NADP؉ -dependent glutamate dehydrogenases (NADP-GDHs) encoded by GDH1 and GDH3 catalyze the synthesis of glutamate from ammonium and ␣-ketoglutarate. The GDH2-encoded NAD ؉ -dependent glutamate dehydrogenase degrades glutamate producing ammonium and ␣-ketoglutarate. Until very recently, it was considered that only one biosynthetic NADP-GDH was present in S. cerevisiae. This fact hindered understanding the physiological role of each isoenzyme and the mechanisms involved in ␣-ketoglutarate channeling for glutamate biosynthesis. In this study, we purified and characterized the GDH1-and GDH3-encoded NADP-GDHs; they showed different allosteric properties and rates of ␣-ketoglutarate utilization. Analysis of the relative levels of these proteins revealed that the expression of GDH1 and GDH3 is differentially regulated and depends on the nature of the carbon source. Moreover, the physiological study of mutants lacking or overexpressing GDH1 or GDH3 suggested that these genes play nonredundant physiological roles. Our results indicate that the coordinated regulation of GDH1-, GDH3-, and GDH2-encoded enzymes results in glutamate biosynthesis and balanced utilization of ␣-ketoglutarate under fermentative and respiratory conditions. The possible relevance of the duplicated NADP-GDH pathway in the adaptation to facultative metabolism is discussed.

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“…Fructose-bisphosphatase was assayed as in [18], malate dehydrogenase as in [19], glutamate dehydrogenase (NAD dependent) as in [20] and cytochrome oxidase as in [21] using in all cases the same assay mixture than in the fructose bisphosphatase assay. Isocitrate lyase was tested as described by Dixon and Kornberg [22].…”

Section: Preparation Of Extracts and Enzyme Assaysmentioning

confidence: 99%

Catabolite repression in yeasts is not associated with low levels of cAMP

Eraso

Gancedo

1984

European Journal of Biochemistry

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The relationship between levels of CAMP and catabolite repression in yeasts has been investigated. Strains of Succharomyces cerevisiae, Schizosaccharomyces pomhe and Kluyuerornyces jrugilis were used. The yeasts were grown on different carbon sources to attain various degrees of repression. Galactose repressed as much as glucose, while maltose was less effective. Full derepression was achieved with ethanol.The enzymes tested were fructose-bisphosphatase, malate dehydrogenase, glutamate dehydrogenase (NAD dependent), cytochrome oxidase and isocitrate lyase (this last enzyme was found to be absent in Schizosaccharomyces).The levels of CAMP were 2 -3 times higher in the repressed conditions than in the derepressed ones. It is therefore concluded that in yeasts catabolite repression is not mediated by a lowering of the intracellular concentration of CAMP.Catabolite repression in yeasts is a well known phenomenon [I] but its underlying mechanism has not been yet established. Since in bacteria catabolite repression is correlated with lowered levels of CAMP (for a review see [2]), it has been tempting to assume that the same situation ocurred in yeast. Indeed some early data on CAMP levels appeared to confirm this idea [3,4] and a more recent review on the subject agreed also with this view [5]. However several results casted doubts on the role of CAMP in mediating catabolite repression in yeast. Montenecourt et al. [6] did not found a clear correlation between the cAMP level and the sensitivity of invertase synthesis to catabolite repression. Also, in yeast strains permeable to cAMP [7] the addition of exogenous cAMP did not prevent glucose repression of galactokinase synthesis [8]. Finally, it has been repeatedly shown that the addition of glucose to a Saccharomyces cerevisiae culture produces an increase in the levels of CAMP [9 -1 I], although this increase was thought to be transient.We decided therefore to reinvestigate systematically the relationship between CAMP levels and catabolite repression in yeasts. Our results show that in different yeast genera catabolite repression is not associated with a decreased level of CAMP. On the contrary, the lowest levels of CAMP are found in yeast not subject to catabolite repression. MATERIALS A N D METHODS Strains ojyeust and growth conditionsThe following yeast strains were used : Succharomyces cerevisiae F11 (obtained from G. Fink) and X2180, Sclzizosuccharomyces pomhe NCYC 972h-and Kluyverornyces fruEnzymes. Fructose-bisphosphatase (EC 3.1.3.11) ; isocitrate lyase (EC 4.1.3.1); malate dehydrogenase (EC 1.1.1.37); glutamate dehydrogenase (NAD dependent) (EC 1.4.1.2); cytochrome oxidase (EC 1.9.3.1).gilis 1407 (obtained from C. Gancedo). The yeasts were grown either on a complex medium with 1 % yeast extract and 2 % peptone or on a mineral medium [12] using NaCl (0.25 g/l) instead of the original sodium citrate and adjusting the initial pH of the medium to 5.5. The different carbon sources were added at 2 % final concentration unless otherwise indicated. Sampling of yeast...

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[119] l-glutamate dehydrogenases (yeast)

Cited by 81 publications

References 1 publication

The Saccharomyces cerevisiae ARO1 gene An example of the co‐ordinate regulation of five enzymes on a single biosynthetic pathway

The Saccharomyces cerevisiae ARO1 gene An example of the co‐ordinate regulation of five enzymes on a single biosynthetic pathway

NADP-Glutamate Dehydrogenase Isoenzymes of Saccharomyces cerevisiae

Catabolite repression in yeasts is not associated with low levels of cAMP

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