Distribution of hexokinase isoenzymes depending on a carbon source in Saccharomyces cerevisiae

Muratsubaki, Haruhiro; Katsume, Takuro

doi:10.1016/0006-291x(79)90220-1

Cited by 22 publications

(10 citation statements)

References 9 publications

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“…cerevisiae, as described previously (e.g. Ramel et al, 1971 ;Muratsubaki & Katsume, 1979). Multiple electrophoretic bands have been found for the hexokinase of other yeast species, such as Hanseniaspora uuarurn (Kloeckera brevis) (Kopperschlager & Hofmann, 1969).…”

Section: Electrophoresissupporting

confidence: 62%

An Unusual Hexose-ATP-Kinase with Two Catalytic Sites and a Role in Carbon Catabolite Repression in the Yeast Schwanniomyces occidentalis

et al. 1987

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The hexose-ATP-kinase of wild-type Schwanniomyces occidentalis (CBS 8 19) is, like hexokinase PI1 of Saccharomyes cerevisiue, associated with carbon catabolite repression and phosphorylates D-glucose and D-fructose. The kinase of Schw. occidentulis repression-resistant (DogR) mutants phosphorylates D-glucose, but not D-fructose. Subjecting the wild-type enzyme to 45 "C for a few minutes appears to alter its activity, specificity and kinetic characteristics to that of the mutant enzyme. Fast protein liquid chromatography, with anion-exchange or gel-filtration columns, gel-electrophoresis, and DNA hybridization with the hexl' mutant of the HXK2 (hexokinase PII) gene of Succh. cerevisiue, all failed to resolve more than one hexose-ATP-kinase in Schw. occidentalis. Hence Schw. occidentulis appears to have a single hexose-ATP-kinase, M , -72 000, with two catalytic sites, analogous to the aspartate kinase/homoserine dehydrogenase of Escherichiu coli. One site is hexokinase-like and associated with catabolite repression and the other is glucokinase-like. Values for apparent K, were 7.2 mM-D-fructose and 0.55 mM-D-glucose ('hexokinase' site) and 0.078 mM-D-glucose ('glucokinase' site). t Present address :

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Section: Electrophoresissupporting

confidence: 62%

An Unusual Hexose-ATP-Kinase with Two Catalytic Sites and a Role in Carbon Catabolite Repression in the Yeast Schwanniomyces occidentalis

et al. 1987

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“…The roles of the three kinases for glucose are not well understood even with respect to metabolism. Although any one of them is adequate for growth on glucose (14), in the wild-type strain, hexokinase B is predominant in growth on glucose and hexokinase A seems to be a repressible enzyme that appears when glucose has been used, up (13,29,30). According to the present work, any one of the three enzymes (for glucose) or two (for fructose) is likewise adequate for low Km uptake.…”

Section: Discussionmentioning

confidence: 94%

Involvement of kinases in glucose and fructose uptake by Saccharomyces cerevisiae.

Bisson¹,

Fraenkel²

1983

Proc. Natl. Acad. Sci. U.S.A.

299

208

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Uptake of glucose, fructose, and the nonmetabolizable analog 6-deoxyglucose was measured in wild-type Saccharomyces cerevuiae and two mutant strains, one (hxkl hxk2) lacking both hexokinase A (P-I) and B (P-Il) but containing glucokinase (and hence able to grow on glucose but not fructose) and the other (hxkl hxk2 gik) also lacking glucokinase (and not able to grow on glucose either). Uptake of the nonmetabolized substances (i.e., 6-deoxyglucose in all three strains, fructose in the two mutants, and glucose in the triple mutant) reached a plateau at or below the external concentration. The kinetic characteristics of uptake were determined from 5-sec incubations by plotting velocity (V) vs. velocity/substrate concentration (V/S) curves. According to such plots, in the wild-type strain uptake had two components, "high affinity uptake" with Km values of ca. 1 mM for glucose and 6 mM for fructose and "low affinity uptake" with Km values of ca. 20 and 50 mM, respectively. The double kinase mutant showed both components for glucose but only the high Km component for fructose, while the triple kinase mutant showed only high Km uptake for both glucose and fructose. Genetic analysis showed that only in strains lacking both hexokinases (hxkl hxk2) was the low Km system for fructose absent. Low Km uptake was restored to the triple mutant by introduction of the cloned wild-type genes: HXK1 orHXK2, for fructose uptake, and HXKl, HXK2, or GLKl, for glucose uptake. A phosphoglucose isomerase mutant had both low and high Km uptake for glucose. These results indicate the presence of two types of uptake mechanism for glucose and fructose in yeast, the functioning of one of which, the low Km system, is influenced by the cognate kinases.Glucose transport in yeast is not well understood. Studies of specificity have implicated a constitutive membrane carrier for uptake of glucose, fructose, and mannose and their analogs (1-3). The internal concentration of glucose is low during its metabolism, and the problem, as posed by van Steveninck and Rothstein (4), has been whether the low concentration reflects metabolic phosphorylation following entry by facilitated diffusion or a more intimate connection between entry and metabolism-for example, a transient phosphorylation during entry, or even formation of the first metabolic intermediate, hexose-6-phosphate, occurring by an obligatory vectorial phosphorylation (as with the bacterial phosphotransferase system). Several experimental lines of evidence seem to implicate metabolism with transport. (i) Considerations of kinetics do not simply accord with a membrane carrier of fixed properties delivering hexose to the cytoplasm (5, 6). (ii) Metabolic inhibitors, such as iodoacetate, are known to affect apparent affinity for uptake (7) and, in derepressed cells, as measured by fermentation rate, affinity for glucose is decreased by oxygen (8). (iii) Experiments with 2-deoxyglucose have established that its internal free poolin whatever compartment-is preceded by 2-deoxyglucose 6-phosphat...

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“…The results from many transformations with plasmids containing the point mutants and deletion fragments were used to generate a fine-structure map of the HXK2 gene directly in yeast cells similar to the maps in procaryotes (Fig. 4) (52); this may explain, at least in part, why the hxkl mutation has no effect, whereas in minimal medium the hxk2 mutation reduces the growth rate as much as do both mutations.…”

Section: And Discussionmentioning

confidence: 99%

Isolation and characterization of mutations in the HXK2 gene of Saccharomyces cerevisiae.

Bloom

Zhu

et al. 1989

Mol. Cell. Biol.

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[25,28,66]) are thus both dispensable for growth on glucose, but the cell requires one or the other for growth on fructose. The two hexokinases are not functionally interchangeable, however, as there are differences in the phenotypes of null mutations in the two genes, notably in the growth rate on glucose and the degree of remaining glucose repression (47).Yeast hexokinase isozymes have been the subject of a considerable number of biochemical studies (for reviews, see references 17 and 59). The in vitro properties of the purified isoenzymes have been characterized previously (20)(21)(22)(69)(70)(71). Chemical modification studies demonstrated that a thiol group (55), a glutamyl residue (58), and at least one arginyl residue (11,57) are essential for the catalytic activity of yeast hexokinase; these residues have not been specifically identified. The pH dependence of hexokinase catalytic activity (72) indicates that an acidic group is crucial for catalysis, further supporting a role for a glutamyl residue in catalysis.The yeast hexokinases have also been studied extensively by X-ray crystallography. The three-dimensional structures of the hexokinase II monomer in a complex with the glucose analog O-toluoylglucosamine (67), its dimer without substrate (4-6), and hexokinase I with glucose (8, 9) have been * Corresponding author.

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Distribution of hexokinase isoenzymes depending on a carbon source in Saccharomyces cerevisiae

Cited by 22 publications

References 9 publications

An Unusual Hexose-ATP-Kinase with Two Catalytic Sites and a Role in Carbon Catabolite Repression in the Yeast Schwanniomyces occidentalis

An Unusual Hexose-ATP-Kinase with Two Catalytic Sites and a Role in Carbon Catabolite Repression in the Yeast Schwanniomyces occidentalis

Involvement of kinases in glucose and fructose uptake by Saccharomyces cerevisiae.

Isolation and characterization of mutations in the HXK2 gene of Saccharomyces cerevisiae.

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