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)

The construction of a xylose-inducible expression vector is described. This vector allows the integration of any gene, coding for its authentic protein, at the amyE locus of Bacillus subtilis (Bs). The controlable expression cassette consists of the repressor-encoding gene and the promoter of the Bacillus megaterium-derived operon for xylose utilization, sandwiched between the 5'- and 3'-ends of amyE. This thereby allows insertion of in vitro constructed transcriptional fusions at the amyE locus of the Bs chromosome. The versatility of this expression system was tested by fusing three different heat-shock genes to the xylose-inducible promoter and following their expression by Western immunoblot analysis. Whereas no increase in the amount of heat-shock protein could be detected under non-inducing conditions when compared to the isogenic wild-type strain, the three proteins were strongly induced after addition of xylose, depending on the gene. To determine the tightness and the induction factor of the system more accurately, the bgaB gene encoding a heat-stable beta-galactosidase (beta Gal) was analyzed. The background activity of beta Gal increased by a factor of at least 200 after addition of xylose. The system is not subject to catabolite, but rather to glucose repression.
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PMID:A xylose-inducible Bacillus subtilis integration vector and its application. 897 10

A modified scheme is proposed for biotyping Gardnerella vaginalis isolated from urinary tract of symptomatic and asymptomatic women based on detection of hippurate hydrolysis, beta-galactosidase (ONPG) and lipase, and fermentation of arabinose, galactose and xylose. Thirty biotypes were found among 73 strains. The distribution of biotypes was similar in both populations but the biotypes 1H, 5G and 7G were found more frequently in women without symptoms of urinary tract infection.
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PMID:Biotypes of Gardnerella vaginalis isolated from urinary tract. 898 6

Phosphorylation of decorin was investigated by incubating a rat fibroblast cell line with radiolabelled phosphate and carbohydrate precursors. There was a transient phosphorylation of the linkage-region saccharides in intracellular decorin prior to assembly of the galactosaminoglycan chain. Phosphorylation gradually increased from xylosylated, galactosyl-xylosylated to galactosyl-galactosyl-xylosylated core protein where all trisaccharide stubs were phosphorylated. Addition of the first glucuronate residue was accompanied by rapid dephosphorylation. Brefeldin A treatment resulted in segregation of galactosaminoglycan synthesis and dephosphorylation. Enzymatic degradation of brefeldin-A-arrested immature proteoglycan with incomplete galactosaminoglycan chain [Moses, J., Oldberg, A., Eklund, E. & Fransson, L.-A. (1997) Eur. J. Biochem., in the press] by using chondroitin AC lyase and chondro-glycuronidase, followed by beta-galactosidase treatment, demonstrated the sequence galactosyl-galactosyl-phosphoxylose. The xylose was resistant to direct periodate oxidation, but sensitive after treatment with alkaline phosphatase, showing that the phosphate was located at C2 of xylose. The transient 2-phosphorylation of xylose may be involved in intracellular transport and/or in the control of modifications of the glycan chain.
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PMID:Biosynthesis of the proteoglycan decorin--transient 2-phosphorylation of xylose during formation of the trisaccharide linkage region. 934 11

The regioselectivity of enzymatic transgalactosidation depends on the source of the beta-galactosidase used. When the galactosyl acceptor only contains secondary hydroxyl groups, e.g., D- or L-xylose, it is possible to find an enzyme that catalyses preferentially the synthesis of any of the three regioisomers 4-, 3- and 2-O-beta-D-galactopyranosyl-D-xylose (1, 2 and 3, respectively) or 4-, 3- and 2-O-beta-D-galactopyranosyl-L-xylose (4, 5 and 6, respectively). Enriched mixtures in 1, 2 or 3 were obtained using beta-galactosidases from Escherichia coli, bovine testes or Aspergillus oryzae, respectively, by transgalactosidation reaction of O-nitrophenyl-beta-D-galactopyranoside and D-xylose, and enriched mixtures in 4, 5 or 6 were obtained in a similar way using beta-galactosidases from Aspergillus oryzae, lamb small-intestine (intestinal lactase-phloridzin hydrolase) or Saccharomyces fragilis, respectively, using L-xylose as acceptor.
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PMID:Regioselectivity of the enzymatic transgalactosidation of D- and L-xylose catalysed by beta-galactosidases. 964 57

A beta-D-glucosidase has been purified to apparent homogeneity from the cotyledons of germinated nasturtium (Tropaeolum majus L.) seedlings during the mobilization of the xyloglucan stored in the cotyledonary cell walls. The purified protein (Mr 76, 000; a glycoprotein; pl > 9.5; apparent pH optimum 4.5; temperature optimum 30 degrees C) catalysed the hydrolysis of p-nitrophenyl-beta-D-glucopyranoside, cello-oligosaccharides, beta-linked glucose disaccharides, and certain xyloglucan oligosaccharides. Glucose disaccharides with different linkages were hydrolysed at different rates [(1-->3) > (1-->4) > (1-->2) > (1-->6)] with significant transglycosylation occurring in the early stages of the reaction. Cello-oligosaccharide hydrolysis was also accompanied by extensive transglycosylation to give transitory accumulations of higher oligosaccharides. At least some of the glycosyl linkages formed during transglycosylation were (1-->6)-beta. Xyloglucan oligosaccharides xylose-substituted at the non-reducing terminal glucose residue (XXXG, XXLG, XLXG and XLLG, where G is an unsubstituted glucose residue, X is a xylose-substituted glucose residue, and L is a galactosylxylose-substituted glucose residue) were not hydrolysed. Some xyloglucan oligosaccharides with an unsubstituted non-reducing terminal glucose residue (GXXG, GXLG and GXG) were hydrolysed, but others (GLXG and GLLG) were not. This indicated steric hindrance by L but not X substitution at the glucose residue next to the one at the non-reducing end of the oligosaccharide. Hydrolysis of xyloglucan oligosaccharides was not accompanied by transglycosylation. Natural xyloglucan subunit oligosaccharides (XXXG, XXLG, XLXG, XLLG) were totally degraded to their monosaccharide components when treated with nasturtium beta-D-galactosidase. (Edwards et al (1988) J. Biol. Chem. 263, 4333-4337), followed by alternations of nasturtium xyloglucan-specific alpha-xylosidase (Fanutti et al (1991) Planta 184, 137-147) and this enzyme. Several extensively overlapping cDNA clones were obtained by RT-PCR and by screening cDNA libraries. A composite, full-length DNA had an open reading frame of 1962 bp, encoding a polypeptide of 654 amino acids, including all N-terminal and internal sequences obtained from the purified beta-glucosidase protein, and a motif resembling plant signal sequences thought to direct proteins to the cell wall. Database searches revealed homology with beta-glucosidases from several sources (plant, bacteria, yeast), notably with glycosylhydrolases of 'Family 3', according to the classification of Henrissat (Henrissat (1991) Biochem. J. 280, 309-316). There was strong sequence homology with a beta-glucan exo-hydrolase from barley (Hrmova et al. (1996) J. Biol. Chem. 271, 5277-5286). The nasturtium beta-glucosidase is ascribed a role in xyloglucan mobilization, and its interaction with the alpha-xylosidase and the beta-galactosidase is modelled.
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PMID:A xyloglucan oligosaccharide-active, transglycosylating beta-D-glucosidase from the cotyledons of nasturtium (Tropaeolum majus L) seedlings--purification, properties and characterization of a cDNA clone. 974 92

The mechanism of induction of secreted beta-galactosidase was studied in the filamentous fungus Penicillium canescens. L-Arabinose and its metabolite L-arabitol induce the synthesis of the enzyme. Apart from beta-galactosidase, L-arabinose induces the synthesis of other extracellular carbohydrolases including alpha-L-arabinofuranosidase. Increasing L-arabinose concentration above 1 mM or addition of other carbon sources results in carbon catabolite repression of the synthesis of the secreted enzymes. The data suggest that arabinofuranosidase can regulate the synthesis of secreted enzymes in P. canescens, thus controlling the level of free L-arabinose.
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PMID:L-Arabinose induces synthesis of secreted beta-galactosidase in the filamentous fungus penicillium canescens 986 69

A low-copy expression vector has been constructed from a 9 Kbp region of the Escherichia coli F plasmid containing the oriV and oriS origins of replication. This plasmid carries the beta-lactamase gene (Apr) and the araBAD promoter/araC regulator for arabinose-inducible gene expression. A derivative which carries a lacZ reporter gene was found to be stably maintained for at least 150 generations. A related multi-copy plasmid was stably maintained in arabinose-free medium, but no plasmid-bearing segregants remained after 60 generations when lacZ expression was induced. Induced expression resulted in 27% (multi-copy) and 12% (low-copy) decreases in growth rate. The uninduced levels of beta-galactosidase were 200 units (multi-copy) and 15 units (low-copy).
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PMID:Construction and characterization of F plasmid-based expression vectors. 1009 85

A gene encoding a third alpha-galactosidase (AglB) from Aspergillus niger has been cloned and sequenced. The gene consists of an open reading frame of 1,750 bp containing six introns. The gene encodes a protein of 443 amino acids which contains a eukaryotic signal sequence of 16 amino acids and seven putative N-glycosylation sites. The mature protein has a calculated molecular mass of 48,835 Da and a predicted pI of 4.6. An alignment of the AglB amino acid sequence with those of other alpha-galactosidases revealed that it belongs to a subfamily of alpha-galactosidases that also includes A. niger AglA. A. niger AglC belongs to a different subfamily that consists mainly of prokaryotic alpha-galactosidases. The expression of aglA, aglB, aglC, and lacA, the latter of which encodes an A. niger beta-galactosidase, has been studied by using a number of monomeric, oligomeric, and polymeric compounds as growth substrates. Expression of aglA is only detected on galactose and galactose-containing oligomers and polymers. The aglB gene is expressed on all of the carbon sources tested, including glucose. Elevated expression was observed on xylan, which could be assigned to regulation via XlnR, the xylanolytic transcriptional activator. Expression of aglC was only observed on glucose, fructose, and combinations of glucose with xylose and galactose. High expression of lacA was detected on arabinose, xylose, xylan, and pectin. Similar to aglB, the expression on xylose and xylan can be assigned to regulation via XlnR. All four genes have distinct expression patterns which seem to mirror the natural substrates of the encoded proteins.
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PMID:Differential expression of three alpha-galactosidase genes and a single beta-galactosidase gene from Aspergillus niger. 1034 26

A new model system for the study of the SOS response has been developed. In this system the response is induced by blocking the replication fork at a Ter site located in pUC-derived plasmids. Blockage of the fork is dependent on the expression of the Ter binding protein, Tus, encoded on another plasmid, in which the tus gene is under the control of the ara promoter. SOS induction can, therefore, be controlled by arabinose. The extent of the SOS response was monitored by measuring the activity of beta-galactosidase, expressed from a lacZ gene fused to the 5' region of the sfiA gene, a typical SOS-responsive gene. Expression of the fusion gene is completely dependent on recA+ and lexA+ genes. Using this system, we found that the distance between the ori and Ter sites is directly correlated with the strength of SOS induction. The properties of this system are discussed.
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PMID:The SOS response is induced by replication fork blockage at a Ter site located on a pUC-derived plasmid: dependence on the distance between ori and Ter sites. 1051 26

Water extractable arabinogalactan-peptide (WE-AGP) isolated from white wheat flour was depolymerized enzymatically to liberate substrate for a galactose oxidase from Dactylium dendroides. A crude liquid pectolytic preparation from Aspergillus niger (p70) displayed activities capable of converting WE-AGP into a substrate for galactose oxidase. The most favorable substrate was observed when WE-AGP was not fully depolymerized into galactose and arabinose. alpha-L-Arabinofuranosidase B from A. niger was also able to produce substrate from WE-AGP; arabinofuranosidase-treated WE-AGP was a better substrate for galactose oxidase than galactose. Treatment by the crude p70 and purified enzymes showed that alpha-L-arabinofuranosidase was partly responsible for the production of substrate, whereas beta-galactosidase did not result in any substrate production or improve the effect of alpha-L-arabinofuranosidase. However, the positive effect of alpha-L-arabinofuranosidase was increased when p70 was added at the same level of arabinofuranosidase activity, suggesting that additional enzyme activities present in p70 were responsible for production of substrate for galactose oxidase.
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PMID:Production of substrate for galactose oxidase by depolymerization of an arabinogalactan-peptide from wheat flour. 1056 3


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