Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycohydrolases assume significance in the metabolism of biological systems and have important industrial applications in the areas of pharmaceuticals, food, and medicine. Glycosidases were screened in germinating seeds, and attempts were made to enhance their levels. Screening of glycosidases in the seedlings during a 72 h germination period revealed higher levels of beta-glucosidase and beta-galactosidase in Trigonella foenum-graecum compared to Cicer arietinum and Vigna radiata. Activity of beta-galactosidase was in general higher than that of beta-glucosidase in all the seedlings tested. During growth, exposure of the seedlings to an allelochemical, mimosine, at 0.1 mM resulted in the enhancement of enzyme levels by 50% in the seedlings of T. foenum-graecum, whereas the addition of mimosine to the assay medium in vitro did not affect the enzyme activities. Hydrolytic activity was enhanced by addition of glycerol in the medium up to 0.1 M in the case of beta-glucosidase and with 0.05 M in the case of beta-galactosidase. In general, the hydrolytic rate was higher by about 30% in the seedlings exposed to mimosine compared to that of the control. Concomitant enhancement in the rates of transgalactosidation by 51% and transglucosidation by 23% was also noted, underscoring the relevance of plant glycohydrolases for appropriate applications.
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PMID:Enhancement of beta-glucosidase and beta-galactosidase of Trigonella foenum-graecum by exposure to the allelochemical mimosine. 1056 17

We are investigating glycosyl hydrolases from new psychrophilic isolates to examine the adaptations of enzymes to low temperatures. A beta-galactosidase from isolate BA, which we have classified as a strain of the lactic acid bacterium Carnobacterium piscicola, was capable of hydrolyzing the chromogen 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-Gal) at 4 degrees C and possessed higher activity in crude cell lysates at 25 than at 37 degrees C. Sequence analysis of a cloned DNA fragment encoding this activity revealed a gene cluster containing three glycosyl hydrolases with homology to an alpha-galactosidase and two beta-galactosidases. The larger of the two beta-galactosidase genes, bgaB, encoded the 76.8-kDa cold-active enzyme. This gene was homologous to family 42 glycosyl hydrolases, a group which contains several thermophilic enzymes but none from lactic acid bacteria. The bgaB gene from isolate BA was subcloned in Escherichia coli, and its enzyme, BgaB, was purified. The purified enzyme was highly unstable and required 10% glycerol to maintain activity. Its optimal temperature for activity was 30 degrees C, and it was inactivated at 40 degrees C in 10 min. The K(m) of freshly purified enzyme at 30 degrees C was 1.7 mM, and the V(max) was 450 micromol. min(-1). mg(-1) with o-nitrophenyl beta-D-galactopyranoside. This cold-active enzyme is interesting because it is homologous to a thermophilic enzyme from Bacillus stearothermophilus, and comparisons could provide information about structural features important for activity at low temperatures.
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PMID:Biochemical and phylogenetic analyses of a cold-active beta-galactosidase from the lactic acid bacterium Carnobacterium piscicola BA. 1058 2

In Bacillus subtilis the citM gene encodes the Mg(2+)-citrate transporter. A target site for carbon catabolite repression (cre site) is located upstream of citM. Fusions of the citM promoter region, including the cre sequence, to the beta-galactosidase reporter gene were constructed and integrated into the amyE site of B. subtilis to study catabolic effects on citM expression. In parallel with beta-galactosidase activity, the uptake of Ni(2+)-citrate in whole cells was measured to correlate citM promoter activity with the enzymatic activity of the CitM protein. In minimal media, CitM was only expressed when citrate was present. The presence of glucose in the medium completely repressed citM expression; repression was also observed in media containing glycerol, inositol, or succinate-glutamate. Studies with B. subtilis mutants defective in the catabolite repression components HPr, Crh, and CcpA showed that the repression exerted by all these medium components was mediated via the carbon catabolite repression system. During growth on inositol and succinate, the presence of glutamate strongly potentiated the repression of citM expression by glucose. A reasonable correlation between citM promoter activity and CitM transport activity was observed in this study, indicating that the Mg(2+)-citrate uptake activity of B. subtilis is mainly regulated at the transcriptional level.
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PMID:Catabolite repression and induction of the Mg(2+)-citrate transporter CitM of Bacillus subtilis. 1102 30

Growth and beta-galactosidase activity of the penicillin producer industrial Penicillium chrysogenum NCAIM 00237 strain were examined using different carbon sources. Good growth was observed using glucose, sucrose, glycerol and galactose, while growth on lactose was substantially slower. beta-Galactosidase activity was high on lactose and very low on all the other carbon sources tested. In glucose grown cultures after exhaustion of glucose as repressing carbon source a derepressed low level of the enzyme was observed. cAMP concentration in lactose grown cultures was relatively high, in glucose grown cultures was low. Caffeine substantially decreased glucose consumption and growth but did not increase beta-galactosidase activity and did not prevent glucose repression which rules out the involvement of cAMP in the regulation of beta-galactosidase biosynthesis in Penicillium chrysogenum.
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PMID:Carbon source regulation of beta-galactosidase biosynthesis in Penicillium chrysogenum. 1180 45

Experiments have been done to show whether the lac promoter delection L1, which partly alleviates catabolite repression, also affects transient repression of lac. In stain L1/F'M15 all of the beta-galactosidase is synthesized from a chromosomal gene cis to L1, whereas 98% of the thiogalactosidase transacetylase is synthesized from an episomal gene cis to an intact i-p-o region. The addition of glucose to induced cultures of strain L1/F'M15 growing in glycerol medium caused extensive transient repression of transacetylase but almost no transient repression of beta-galactosidase. In control experiments with a diploid stain of genotype p(+)z(+)a(-)/F'p(+)z(-)a(+) the two enzymes suffered equal transient repression. Thus L1 substantially relieves transient repression.
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PMID:Transient repression of the lac operon - the effect of a lac promoter deletion. 1194 82

When fed to a beta-galactosidase-negative (lacZ(-)) Escherichia coli strain that was grown on an alternative carbon source (such as glycerol), lactose accumulated intracellularly on induction of the lactose permease. We showed that intracellular lactose was efficiently glycosylated when genes of glycosyltransferase that use lactose as acceptor were expressed. High-cell-density cultivation of lacZ(-) strains that overexpressed the beta 1,3 N acetyl glucosaminyltransferase lgtA gene of Neisseria meningitidis resulted in the synthesis of 6 g x L(-1) of the expected trisaccharide (GlcNAc beta 1-3Gal beta 1-4Glc). When the beta 1,4 galactosyltransferase lgtB gene of N. meningitidis was coexpressed with lgtA, the trisaccharide was further converted to lacto-N-neotetraose (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc) and lacto-N-neoheaxose with a yield higher than 5 g x L(-1). In a similar way, the nanA(-) E. coli strain that was devoid of NeuAc aldolase activity accumulated NeuAc on induction of the NanT permease and the lacZ(-) nanA(-) strain that overexpressed the N. meningitidis genes of the alpha2,3 sialyltransferase and of the CMP-NeuAc synthase efficiently produced sialyllactose (NeuAc alpha 2-3Gal beta 1-4Glc) from exogenous NeuAc and lactose.
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PMID:A new fermentation process allows large-scale production of human milk oligosaccharides by metabolically engineered bacteria. 1204 46

A facultatively anaerobic bacterium, designated strain COOI3B(T) (= ATCC BAA 136T = DSM 13966T), was isolated from the waters emitted by a bore well tapping the deep subterranean thermal waters of the Great Artesian Basin of Australia. The cells were straight to slightly curved rods (0.5-0.8 x 2-25 microm) that occurred singly and rarely in pairs or in chains. Strain COOI3B(T) was motile by peritrichous flagella. It stained gram-negative, but electron micrographs showed a gram-positive-type cell wall. Spores were never observed and cells were heat-sensitive. Yeast extract at 0.02% (w/v) was required for growth and could also be used as a sole carbon and energy source at concentrations higher than 0.1% (w/v). The strain utilized amorphous iron(III), manganese(IV), nitrate, nitrite and fumarate as electron acceptors in the presence of yeast extract, glucose, sucrose, fructose, maltose, xylose, starch, glycerol, ethanol or lactate. Electron acceptors were not obligately required and growth was better in the presence of nitrate than in its absence. Acid was not produced from growth on carbohydrates. Tryptophan deaminase, H2S, arginine dihydrolase, lysine decarboxylase, beta-galactosidase, arabinosidase, glucuronidase, glucosaminidase, nitroanilidase, xylosidase and ornithine decarboxylase were not produced. Starch and gelatin, but not casein, were hydrolysed. Aesculin and catalase, but not oxidase and urease, were produced. Strain COOI3B(T) grew optimally at temperatures between 37 and 40 degrees C (the temperature growth range was 25-45 degrees C) and at pH 7.0-9.0 (the pH growth range was 6.0 to 9.5) with 5% (w/v) NaCl (the NaCl concentration growth range was 0.9%, w/v). The DNA base composition was 43 +/- 1 mol % G+C. Phylogenetic analysis indicated that it was a member of the family Bacillaceae, Bacillus infernus and Bacillus firmus being the closest phylogenetic neighbours (having a mean similarity value of 96%); hence, strain COOI3B(T) is designated as a novel species, Bacillus subterraneus sp. nov.
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PMID:Bacillus subterraneus sp. nov., an iron- and manganese-reducing bacterium from a deep subsurface Australian thermal aquifer. 1205 51

To obtain a high cell density of recombinant Saccharomyces cerevisiae (INVSc 1 strain bearing a 2 microm plasmid, pYES2 containing a GAL1 promoter for expression of the beta-galactosidase gene), the yeast was grown with glycerol as the substrate by fed-batch fermentation. The feeding strategy was based on an on-line response of the medium pH to the consumption of glycerol. The approach was to feed excess carbon into the medium to create a benign environment for rapid biomass buildup. During cell growth in the presence of glycerol, the release of protons in the medium caused a decrease in pH and the consumption rate of ammonium phosphate served as an on-line indicator for the metabolic rate of the organism. The extent of glycerol feeding in a fed-batch mode with pH control at 5.0 +/- 0.1 was ascertained from the automatic addition of ammonium phosphate to the medium. The glycerol feeding to ammonium phosphate addition ratio was found to be 2.5-3.0. On the basis of the experiments, a maximum dry cell biomass of 140 g per liter and a productivity of 5.5 g DCW/L/h were achieved. The high cell density of S. cerevisiae obtained with good plasmid stability suggested a simple and efficient fermentation protocol for recombinant protein production.
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PMID:High-cell-density fermentation of recombinant Saccharomyces cerevisiae using glycerol. 1236 68

We have reported previously that multiple copies of MRG19 suppress GAL genes in a wild-type but not in a gal80 strain of Saccharomyces cerevisiae. In this report we show that disruption of MRG19 leads to a decrease in GAL induction when S. cerevisiae is induced with 0.02% but not with 2.0% galactose. Disruption of MRG19 in a gal3 background (this strain shows long-term adaptation phenotype) further delays the GAL induction, supporting the notion that its function is important only under low inducing signals. As a corollary, disruption of MRG19 in a gal80 strain did not decrease the constitutive expression of GAL genes. These results suggest that MRG19 has a role in GAL regulation only when the induction signal is weak. Unlike the effect on GAL gene expression, disruption of MRG19 leads to de-repression of CYC1-driven beta-galactosidase activity. MRG19 disruptant also showed a twofold increase in the rate of oxygen uptake as compared with the wild-type strain. ADH2, CTA1, DLD1, and CYC7 promoters that are active during nonfermentative growth did not show any de-repression of beta-galactosidase activity in the MRG19 disruptant. Western blot analysis indicated that MRG19 is a glucose repressible gene and is expressed in galactose and glycerol plus lactate. Experiments using green fluorescent protein fusion constructs indicate that Mrg19p is localized in the nucleus consistent with the presence of a consensus nuclear localization signal sequence. Based on the above results, we propose that Mrg19p is a regulator of galactose and nonfermentable carbon utilization.
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PMID:Molecular characterization of MRG19 of Saccharomyces cerevisiae. Implication in the regulation of galactose and nonfermentable carbon source utilization. 1244 72

The regulation of formation of the single intracellular beta-galactosidase activity of Aspergillus nidulans was investigated. beta-Galactosidase was not formed during growth on glucose or glycerol, but was rapidly induced during growth on lactose or D-galactose. L-Arabinose, and -- with lower efficacy -- D-xylose also induced beta-galactosidase activity. Addition of glucose to cultures growing on lactose led to a rapid decrease in beta-galactosidase activity. In contrast, in cultures growing on D-galactose, addition of glucose decreased the activity of beta-galactosidase only slightly. Glucose inhibited the uptake of lactose, but not of D-galactose, and required the carbon catabolite repressor CreA for this. In addition, CreA also repressed the formation of basal levels of beta-galactosidase and partially interfered with the induction of beta-galactosidase by D-galactose, L-arabinose, and D-xylose. D-Galactose phosphorylation was not necessary for beta-galactosidase induction, since induction by D-galactose occurred in an A. nidulans mutant defective in galactose kinase, and by the non-metabolizable D-galactose analogue fucose in the wild-type strain. Interestingly, a mutant in galactose-1-phosphate uridylyl transferase produced beta-galactosidase at a low, constitutive level even on glucose and glycerol and was no longer inducible by D-galactose, whereas it was still inducible by L-arabinose. We conclude that biosynthesis of the intracellular beta-galactosidase of A. nidulans is regulated by CreA, partially repressed by galactose-1-phosphate uridylyl transferase, and induced by D-galactose and L-arabinose in independent ways.
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PMID:Regulation of formation of the intracellular beta-galactosidase activity of Aspergillus nidulans. 1247 99


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