Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A recessive mutant cat1-1, wild type CAT1, was isolated in Saccharomyces cerevisiae. It did not grow on glycerol nor ferment maltose even with fully constitutive, glucose resistant maltase synthesis. It prevented derepression of isocitrate lyase, fructose-1,6-diphosphatase and maltase in a constitutive but glucose sensitive maltase mutant. Derepression of malate dehydrogenase was retarded and slowed down. Sucrose fermentation and invertase synthesis was not affected. Respiration was normal. From this mutant, two reverse mutants were isolated. One was recessive, acted as a suppressor of cat1-1 and was called cat2-1, wild type CAT2; the other was dominant and allelic to CAT1 and designated CAT1-2d and cat2-1 caused an earlier derepression of enzymes studied but did not affect the repressed nor the fully derepressed enzyme levels. CAT1-2d and cat2-1 did not show any additive effects. It is proposed that carbon catabolite repression acts in two ways. The direct way represses synthesis of sensitive enzymes, during growth on repressing carbon sources whereas the other way regulates the derepression process. After alleviation of carbon catabolite repression, gene CAT1 becomes active and prevents the activity of CAT2 which functions as a repressor of sensitive enzyme synthesis. The CAT2 gene product has to be eliminated before derepression can actually occur. The time required for this causes a delay in derepression after the depletion of a repressible carbon source. cat1-1 cannot block CAT2 activity and therefore, derepression is blocked. cat2-1 is inactive and derepression can start after carbon catabolite repression has ceased. CAT1-2d permanently active as a repressor of CAT2 and eliminates the delay in derepression.
Mol Gen Genet 1977 Feb 28
PMID:Genetics of carbon catabolite repression in Saccharomycess cerevisiae: genes involved in the derepression process. 19 40

Mutants with defective carbon catabolite repression have been isolated in the yeast Saccharomyces cerevisiae using a selective procedure. This was based on the fact that invertase is a glucose repressible cell wall enzyme which slowly hydrolyses raffinose to yield fructose and that the inhibitory effects of 2-deoxyglucose can be counteracted by fructose. Repressed cells were plated on a raffinose--2-doexyglucose medium and the resistant cells growing up into colonies were tested for glucose non-repressible invertase and maltase. The yield of regulatory mutants was very high. All were equally derepressed for invertase and maltase, no mutants were obtained with only non-repressible invertase synthesis which was the selected function. A total of 61 mutants isolated in different strains were allele tested and could be attributed to three genes. They were all recessive. Mutants in one gene had reduced hexokinase activities, the other class, located in a centromere linked gene, had elevated hexokinase levels and was inhibited by maltose. Mutants in a third gene were isolated on a 2-deoxyglucose galactose medium and had normal hexokinase levels. A partial derepression was observed for malate dehydrogenase in all mutants. Isocitrate lyase, however, was still fully repressible.
Mol Gen Genet 1977 Jul 07
PMID:Mutants of Saccharomyces cerevisiae resistant to carbon catabolite repression. 19 90

Yeast mutants with glucose-insensitive formation of mitochondrial enzymes were isolated starting with a strain completely lacking alcohol dehydrogenase activity. The mutations could uniquely be attributed to a single nuclear gene, designated CCR80. They were largely dominant. Glucose-resistant enzyme formation was most prominent with regard to mitochondrial enzymes succinate dehydrogenase and NADH: cytochrome c oxidoreductase. The effect of CCR80r mutations was rather small but significant on the gluconeogenetic enzymes isocitrate lyase, malate synthase and fructose-1,6-bisphosphatase and on invertase synthesis. The repressive effect of maltose in CCR80r mutants was also reduced showing that glucose-resistance is not caused by a mere hexose uptake defect. This regulatory disorders were not accompanied by reduced levels of glycolytic enzymes or drastically altered levels of glycolytic intermediates. Aerobic fermentation of glucose was almost completely inhibited in the mutants; anaerobic glucose degradation was reduced but not completely abolished. Therefore, the mutants appear to be altered in the regulation of glycolysis. A largely glucose-resistant synthesis of respiratory enzymes is obviously a corollary of this alteration.
Mol Gen Genet 1978 Feb 27
PMID:A yeast mutant with glucose-resistant formation of mitochondrial enzymes. 20 62

The two mutants (abs) and (wal) affecting the cell morphology of yeast lead also to higher in vivo activities of the cell wall enzymes acid phosphatase, invertase and melibiase.
Mol Gen Genet 1979 Jun 07
PMID:Pieiotropic effect of two cell wall mutants on the activity of some cell wall enzymes in the yeast Saccharomyces cerevisiae. 22 35

Because the cot-2 and inv loci of Neurospora crassa are closely linked, the invertase from the morphological mutant, cot-2, was examined. The cot-2 strains produce an invertase with altered heat sensitivity, Km, and ratio of heavy to light forms. The cellular localization of cot-2 invertase is different from that of the wild type. There were no observable changes in the energy of activation or the pH optimum of cot-2 invertase, and some of the differences detected were not apparent under culture conditions that promoted wild-type growth. Since recombination (about 5 percent) occurred between cot-2 and inv and culture conditions affected the enzyme characteristics, we suggest cot-2 determines, in part, the carbohydrate composition of the enzyme.
J Gen Microbiol 1975 Jul
PMID:An altered invertase in the cot-2 mutant of Neurospora crassa. 23 95

Extracts of Streptococcus mitis ATCC 903 were analysed for beta-fructofuranosidase and alpha-glucosidase activities by isoelectric focusing in thin-layer polyacrylamide gels combined with zymogram procedures. Three bands of activity were visualized in the gels after incubation with sucrose (pI 4.05, 4.25 and 4.85) and three other bands after incubation with p-nitrophenyl alpha-D-glucopyranoside (pI 3.90, 4.45 and 4.65). The enzymes responsible for the reaction with sucrose were identified as beta-fructofuranosidases (EC 3.2.1.26) for the following reasons: identical enzyme bands were visualized in the gels after incubation with raffinose; no enzyme bands appeared in the gel after incubation with the alpha-glucosides maltose, turanose, trehalose and melezitose; and the soluble fraction hydrolysed sucrose to equimolar amounts of glucose and fructose.
J Gen Microbiol 1978 Jun
PMID:Isoelectric focusing studies on the beta-fructofuranosidases and alpha-glucosidases of Streptococcus mitis. 35 25

Invertase formation in the yeast Saccharomyces cerevisiae is subject to repression by hexoses in the growth medium. Mutagen-induced (ethyl methanesulfonate or N-methyl-N-nitro-nitrosoguanidine) invertase hyperproducer mutants have been derived from the SUC3 MAL3 strain EK-6B by selecting for their ability to grow on media containing the sugar raffinose plus 2-deoxy-D-glucose (2DG). Raffinose like sucrose is a betta-fructoside which can be hydrolyzed by yeast invertase (beta-fructoside which can be hydrolyzed by yeast invertase (beta-fructofuranoside fructohydrolase). These mutants, designated dgr, produce higher levels of invertase (pi-glucosidase levels are also elevated but to a lesser extent) under conditions normally repressing invertase biosynthesis in the parent. Invertases of mutants dgr2 and dgr3 are indistinguishable from that of EK-6B with respect to their Km's for sucrose and thermal labilities. Genetic studies revealed that dgr2 and dgr3 are recessive and unlinked to the SUC3 gene.
Mol Gen Genet 1978 Sep 08
PMID:Genetic control of invertase formation in Saccharomyces cerevisiae. II. Isolation and characterization of mutants conferring invertase hyperproduction in strain EK-6B carrying the SUC3 gene. 36 57

The activities of ornithine aminotransferase, sucrase and acid and alkaline phosphatases have been studied throughout sporulation in Saccharomyces cerevisiae. The same enzymes were monitored during synchronous vegetative growth. Each of these enzymes has been demonstrated to increase in a 'step' manner during both growth and sporulation. Alkaline phosphatase increased in a two-step manner whereas the others increased in a single step. The times of increase of these enzymes formed a similar sequence during both sporulation and growth. It has been proposed that these enzymes are under a common mechanism of control during growth and sporulation and that the sequence of enzyme appearance may be used as markers of the sporulation process.
J Gen Microbiol 1978 Dec
PMID:The use of step enzymes as markers during meiosis and ascospore formation in Saccharomyces cerevisiae. 37 Mar 42

Sucrose catabolism was studied in Rhodopseudomonas capsulata. Sucrose was hydrolysed by the action of a constitutive cytoplasmic sucrase. The use of a glucose-6-phosphate dehydrogenase-deficient mutant and radiorespirometric experiments demonstrated that both the glucose and fructose moieties of sucrose were catabolized via the Entner-Doudoroff pathway. This result was confirmed by enzyme analysis and studies on sugar assimilation. All the enzymes of the Entner-Doudoroff pathway were present in bacteria grown on secrose but fructokinase (EC 1.7.1.4) activity was relatively low. In contrast, phosphoenolpyruvate:fructose phosphotransferase and 1-phosphofructokinase, the key enzymes for the catabolism of exogenous fructose, were only partially induced. Bacteria grown on sucrose and treated with chloramphenicol were, therefore, not able to assimilate exogenous fructose. We conclude that under these conditions endogenous fructose is catabolized via the Entner-Douboroff pathway, while exogenous fructose is degraded via fructose 1-phosphate and the Embden-Meyerhof pathway.
J Gen Microbiol 1978 Apr
PMID:An alternative pathway for the degradation of endogenous fructose during the catabolism of sucrose in Rhodopseudomonas capsulata. 64 27

The role of mitochondria in carbon catabolite repression in Saccharomyces cerevisiae was investigated by comparing normal, respiratory competent (RHO) strains with their mitochondrially inherited, respiratory deficient mutant derivatives (rho). Formation of maltase and invertase was used as an indicator system for the effect of carbon catabolite repression on carbon catabolic reactions. Fermentation rates for glucose, maltose and sucrose were the same in RHO and rho strains. Specific activities of maltase and invertase were usually higher in the rho-mutants. A very pronounced difference in invertase levels was observed when cells were grown on maltose; rho-mutants had around 30 times more invertase than their RHO parent strains. The fact that rho-mutants were much less sensitive to carbon catabolite repression of invertase synthesis than their RHO parents was used to search for the mitochondrial factor(s) or function(s) involved in carbon catabolite repression. A possible metabolic influence of mitochondria on this system of regulation was tested after growth of RHO strains under anaerobic conditions (no respiration nor oxidative phosphorylation), in the presence of KCN (respiration inhibited), dinitrophenol (uncoupling of oxidative phosphorylation) and of both inhibitors anaerobic conditions and dinitrophenol had no effect on the extent of invertase repression. KCN reduced the degree of repression but not to the level found in rho-mutants. A combination of both inhibitors gave the same results as with KCN alone. Erythromycin and chloramphenicol were used as specific inhibitors of mitochondrial protein synthesis. Erythromycin prevented the formation of mitochondrial respiratory systems but did not induce rho-mutants under the conditions used. However, repression of invertase was as strong as in the absence of the inhibitor. Chloramphenicol led only to a slight reduction of the respiratory systems and did not affect invertase levels. A combination of both antibiotics had about the same effect as growth in the presence of KCN. The results showed that mitochondria are involved in carbon catabolite repression and they cause an increase in the degree of repression. These effects cannot be due to mere metabolic activities nor to factors made on the mitochondrial protein synthesizing machinery. This regulatory role of mitochondria is observed as long as an intact mitochondrial genome is maintained.
Mol Gen Genet 1976 Oct 18
PMID:The role of mitochondria in carbon catabolite repression in yeast. 79 Jan 58


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