Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The P4 variant of Dictyostelium discoideum is characterized by the production of fruiting structures in which the overall proportion of stalk to spore material is increased, relative to the wild type. The altered morphology of the mutant is due to increased sensitivity to cyclic AMP which promotes stalk cell differentiation. In the presence of 10-4 M-cyclic AMP the entire population of P4 amoebae forms clumps of stalk cells on the surface of the dialysis membrane support. Measurement of changes in activity of a range of developmentally-regulated enzymes during the development of P4 in the presence and absence of cyclic AMP has allowed us to identify three classes of enzyme: (i) Those, such as beta-glucosidase II, trehalose-6-phosphate synthetase and uridine diphosphogalactose-4-epimerase, which are required for the production of spores. (ii) Enzymes, primarily but perhaps not exclusively, required during stalk cell formation. Typical of these are N-acetylglucosaminidase and alkaline phosphatase. (iii) General enzymes, such as threonine dehydrase, alpha-mannosidase and uridine diphosphoglucose pyrophyosphorylase, which are present inboth pre-stalk and pre-spore cells and appear to be necessary for the development of both cell types.
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PMID:Enzyme activity changes during cyclic AMP-induced stalk cell differentiation in P4, a variant of Dictyostelium discoideum. 17 91

1. The rates of accumulation (enzyme units/h per 10(8) cells) of a number of glycosidase activities were studied in Dictyostelium discoideum cells during the growth and differentiation phases of this organism's life cycle. 2. The rates of accumulation of the enzymes beta-N-acetylglucosaminidase, alpha-glucosidase and beta-galactosidase remain unchanged during the growth and early differentiation phases. 3. The considerable changes in specific activity of the enzymes which occur in the early differentiation phase are due to the massive loss of total cellular protein which occurs at this time. 4. Significant alterations can occur in the rates of accumulation of alpha-mannosidase during both the growth and differentiation phases, and since, on the onset of differentiation, beta-glucosidase activity is excreted and degraded, the rate of accumulation of this enzyme differs in the growth and differentiation phases. 5. The characteristic rates of accumulation of all these glycosidases change markedly with changes in the growth conditions of the myxamoebae, and thus these rates of synthesis must be regulated independently; however, addition of cyclic AMP to the growth medium has no effect on them.
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PMID:Rates of accumulation of glycosidase activities during growth and differentiation of Dictyostelium discoideum. 117 88

A temperature-sensitive mutant of Dictyostelium discoideum has been isolated based on its lack of chemotaxis toward cyclic AMP at the restrictive temperature, 27 degrees C. The mutant develops normally at the permissive temperature, 22 degrees C, but fails to aggregate or complete development at the restrictive temperature. The temperature-sensitive phenotype can be bypassed by allowing cultures to grown into late log phase or to starve for 60-90 min at 22 degrees C prior to a shift to 27 degrees C. At 27 degrees C, the mutant overproduces cell surface cyclic AMP receptors of both high and low affinity and is capable of spontaneous oscillations in light scattering in cell suspensions. Despite its complete lack of morphological development, the mutant undergoes extensive biochemical differentiation. At the onset of starvation, it shows increased levels of N-acetylglucosaminidase, it express cyclic AMP receptors at the normal time and, although somewhat slowly, suppresses those receptors as if aggregation had been achieved. Metabolic pulse labellings with [35S]methionine revealed that the mutant at 27 degrees C displays the same changes in the patterns of newly synthesized proteins observed during the vegetative-to-aggregation and the aggregation-to-slug stages of normal development. The only clear difference from wild type was the failure of the culmination-stage isozyme of beta-glucosidase to appear. The mutant is defective in establishment of intercellular cohesion mechanisms, correlated with poor agglutination by concanavalin A, at the restrictive temperature. The properties of the mutant place severe constraints on models regarding the role of chemoreception and intercellular cohesion in regulation of gene expression.
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PMID:Biochemical differentiation in a mutant of Dictyostelium discoideum defective in cyclic AMP chemotaxis and in intercellular cohesion. 256 Jul 9

Bacteroides ruminicola B(1)4, a predominant ruminal and cecal bacterium, was grown in batch and continuous cultures, and beta-glucosidase activity was measured by following the hydrolysis of p-nitrophenyl-beta-glucopyranoside. Specific activity was high when the bacterium was grown in batch cultures containing cellobiose, mannose, or lactose (greater than 286 U/g of protein). Activity was reduced approximately 90% when the organism was grown on glucose, sucrose, fructose, maltose, or arabinose. The specific activity of cells fermenting glucose was initially low but increased as glucose was depleted. When glucose was added to cultures growing on cellobiose, beta-glucosidase synthesis ceased immediately. Catabolite repression by glucose was not accompanied by diauxic growth and was not relieved by cyclic AMP. Since glucose-grown cultures eventually exhibited high beta-glucosidase activity, cellobiose was not needed as an inducer. Catabolite repression explained beta-glucosidase activity of batch cultures and high-dilution-rate chemostats where glucose accumulated, but it could not account for activity at slow dilution rates. Maximal beta-glucosidase activity was observed at a dilution rate of approximately 0.35 h-1, and cellobiose-limited chemostats showed a 15-fold decrease in activity as the dilution rate declined. An eightfold decline was observed in glucose-limited chemostats. Since inducer availability was not a confounding factor in glucose-limited chemostats, the growth rate-dependent derepression could not be explained by other mechanisms.
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PMID:Regulation of beta-glucosidase in Bacteroides ruminicola by a different mechanism: growth rate-dependent derepression. 312 55

Escherichia coli K12 does not metabolize beta-glucosides such as arbutin and salicin because of lack of expression of the bglBSRC operon, which contains structural genes for transport (bglC) and hydrolysis (bglB) of phospho-beta-glucosides. Mutants carrying lesions in the cis-acting regulatory site bglR metabolize beta-glucosides as a consequence of expression of this cryptic operon (Prasad and Schaefler 1974). We isolated mutations promoting beta-glucoside metabolism that were unlinked to bglR; some of these mutations were shown to be amber. All of them were mapped at 27 min on the E. coli K12 linkage map and appeared to define a single gene, for which we propose the designation bglY. Utilization of beta-glucosides in bglY mutants appeared to be a consequence of expression of the bglBSRC operon, since bglB bglR and bglB bglY double mutants had the same phenotype. All bglY mutations analyzed were recessive to the wild-type bglY+ allele. Phospho-beta-glucosidase B and beta-glucoside transport activities are inducible in bglY mutants, as they are in bglR mutants. Metabolism of beta-glucosides in both bglR and bglY mutants required cyclic AMP. We propose that bglY encodes a protein acting as a repressor of the bglBSRC operon, active in both the presence and absence of beta-glucosides, whose recognition site would be within the bglR locus.
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PMID:Cryptic operon for beta-glucoside metabolism in Escherichia coli K12: genetic evidence for a regulatory protein. 626 10

Teratocarcinoma stem cell F9 expressed a potent fucosyltransferase activity acting on asialofetuin. A majority of the product was susceptible to alpha-L-fucosidase I from almond emulsin, indicating that the linkage formed was mainly Fuc alpha 1 leads to 3GlcNAc. The specific activity of the transferase decreased when the stem cells were induced to differentiate into parietal endoderm cells by retinoic acid and dibutyryl cyclic AMP. Furthermore, PYS-2 cell, a parietal endoderm cell line virtually lacked the transferase. The change in the fucosyltransferase activity could be correlated with cell surface changes occurring during differentiation.
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PMID:A fucosyltransferase in teratocarcinoma stem cells. Decreased activity accompanying differentiation to parietal endoderm cells. 631 85

beta-Glucosidase activity was induced in Streptomyces venezuelae during growth on cellobiose, gentiobiose, salicin, methyl beta-glucoside, and p-nitrophenyl beta-D-glucopyranoside. Activity in cell extracts was separated by DEAE-cellulose chromatography into two fractions differing in substrate preference. One component showed higher activity with, and was more strongly induced by, cellobiose; the other showed greater activity and inducibility with salicin. Addition of glucose to cultures severely depressed induction of beta-glucosidase activity by cellobiose but not by salicin. Acetate and several amino acids inhibited induction by either substrate. The action of glucose was not reversed by cyclic AMP. Cultures of S. venezuelae using glucose, cellobiose, or a mixture of the two saccharides as their carbon source produced chloramphenicol during growth. In contrast with its effect on the induction of cellobiose activity, glucose did not suppress chloramphenicol production, indicating that the control mechanisms that establish carbon source preferences are not linked to those that regulate antibiotic biosynthesis in this organism.
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PMID:Glucose suppression of beta-glucosidase activity in a chloramphenicol-producing strain of Streptomyces venezuelae. 681 Nov 18

When cells of the slime mould Dictyostelium discoideum are allowed to starve in the presence of alpha-chymotrypsin, they are blocked in development at the stage where tight aggregates form tips. Analysis of developmentally regulated enzymes has shown that alpha-mannosidase, beta-N-acetylglucosaminidase, threonine deaminase, tyrosine aminotransferase, beta-glucosidase and the carbohydrate-binding protein discoidin are unaffected, but enzymes that show an increase in specific activity during post-aggregative development, namely glycogen phosphorylase, UDP-glucose pyrophosphorylase, UDP-galactose 4-epimerase, UDP-galactose polysaccharide transferase and alkaline phosphatase, did not show the characteristic increase when development was blocked by alpha-chymotrypsin. Recovery of cells from the effects of alpha-chymotrypsin was accompanied by the formation of fruiting bodies and a concomitant increase in the specific activity of UDP-glucose pyrophosphorylase. Uptake or efflux of 45Ca2+ was not altered in the presence of alpha-chymotrypsin. Cells allowed to develop in alpha-chymotrypsin, or treated with the enzyme for 15 min, had a markedly reduced ability to bind cyclic AMP with low affinity; high-affinity binding was unaffected. Pronase had a similar effect on cyclic AMP binding, but trypsin, which does not alter developmental processes, has no effect on cyclic AMP binding to D. discoideum cells.
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PMID:Developmentally regulated enzymes and cyclic AMP-binding sites in Dictyostelium discoideum cells blocked during development by alpha-chymotrypsin. 715 Feb 39

Agrobacterium tumefaciens strain C58 was able to utilize carbon from cellobiose and some other beta-D-glucosides as efficiently as from glucose. beta-D-glucoside utilization was partially inducible and the induction was subject to catabolite repression by glucose, independently of the presence of cyclic AMP in the medium. It was also independent of Ti plasmid-encoded functions. beta-D-glucosides were hydrolysed by a single, cytoplasmic and constitutively expressed beta-glucosidase, which was active on non-phosphorylated substrates and insensitive to glucose inhibition.
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PMID:Utilization of cellobiose and other beta-D-glucosides in Agrobacterium tumefaciens. 852 65

beta-Glucosidase activity in Myceliophthora thermophila D-14 (= ATCC 48104) was inducible and was produced in culture filtrate during growth with various inducers, of which PNPG (p-nitrophenyl-beta-d-glucoside) was the most efficient. Induction of beta-glucosidase also occurred when the organism was grown in medium supplemented with different carbon sources. Carboxymethyl cellulose, cellobiose, and Solka-Floc were found effective for induction of enzyme biosynthesis. The addition of glucose to the culture medium severely repressed beta-glucosidase synthesis, which could not be reversed by exogenous cyclic AMP or dibutyryl cyclic AMP.
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PMID:Induction and Catabolite Repression of beta-Glucosidase Synthesis in Myceliophthora thermophila D-14 (= ATCC 48104). 1634 25


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