PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “GLUCOSYLTRANSFERASES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1994

The submicrosomal localization of uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase and bile acid glucosyltransferase in the human liver.

Uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase and bile acid glucosyltransferase were quantitatively determined in subcellular fractions obtained by differential centrifugation of human liver homogenate. Both enzymes were exclusively enriched in the microsomal fraction with a recovery of total enzyme activity of 65.9 +/- 9.9% and 69.1 +/- 13.8%, respectively. Microsomal preparations were further subfractionated by isopycnic centrifugation on a continuous sucrose density gradient. Both glucosyltransferases closely followed marker constituents of endoplasmic reticulum, as shown by similar distribution profiles in the gradient, but differed in their quantitative distribution among the endoplasmic reticulum membranes. The bile acid glucosyltransferase showed an almost identical distribution with NADPH-cytochrome c reductase as marker of smooth endoplasmic reticulum with a modal density of 1.16 g/cm3. The uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase equilibrated at a higher density with a peak at a model density of 1.174 g/cm3. Its marked overlap with the distribution of NADPH-cytochrome c reductase suggests that the major activity of uridine 5'-diphosphate-glucose dolichyl-phosphate glucosyltransferase is also associated with smooth endoplasmic reticulum membranes, whereas minor proportions of enzyme activity are present in the rough endoplasmic reticulum. Association of both glucosyltransferases with membranes derived from Golgi-complex or plasma membranes could be excluded by treatment of microsomes with membrane reagents prior to isopycnic centrifugation. Digitonin did not alter the equilibrium densities of the glucosyltransferases and endoplasmic reticulum markers in contrast to markers of plasma membranes and the Golgi-complex shifting to higher densities. The reversed effect was observed in case of pretreatment of microsomes with pyrophosphate known to detach ribosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1997

Are the characteristics of betanidin glucosyltransferases from cell-suspension cultures of Dorotheanthus bellidiformis indicative of their phylogenetic relationship with flavonoid glucosyltransferases?

Uridine 5'-diphosphoglucose:betanidin 5-O- and 6-O-glucosyltransferases (5-GT and 6-GT; EC 2.4.1) catalyze the regiospecific formation of betanin (betanidin 5-O-beta-glucoside) and gomphrenin I (betanidin 6-O-beta-glucoside), respectively. Both enzymes were purified to near homogeneity from cell-suspension cultures of Dorotheanthus bellidiformis, the 5-GT by classical chromatographic techniques and the 6-GT by affinity dye-ligand chromatography using UDP-glucose as eluent. Data obtained with highly purified enzymes indicate that 5-GT and 6-GT catalyze the indiscriminate transfer of glucose from UDP-glucose to hydroxyl groups of betanidin, flavonols, anthocyanidins and flavones, but discriminate between individual hydroxyl groups of the respective acceptor compounds. The 5-GT catalyzes the transfer of glucose to the C-4' hydroxyl group of quercetin as its best substrate, and the 6-GT to the C-3 hydroxyl group of cyanidin as its best substrate. Both enzymes also catalyze the formation of the respective 7-O-glucosides, but to a minor extent. Although the enzymes were not isolated to homogeneity, chromatographic, electrophoretic and kinetic properties proved that the respective enzyme activities were based on the presence of single enzymes, i.e. 5-GT and 6-GT. The N terminus of the 6-GT revealed high sequence identity to a proposed UDP-glucose: flavonol 3-O-glucosyltransferase (UF3GT) of Manihot esculenta. In addition to the 5-GT and 6-GT, we isolated a UF3GT from D. bellidiformis cell cultures that preferentially accepted myricetin and quercetin, but was inactive with betanidin. The same result was obtained with a UF3GT from Antirrhinum majus and a flavonol 4'-O-glucosyltransferase from Allium cepa. Based on these results, the main question to be addressed reads: Are the characteristics of the 5-GT and 6-GT indicative of their phylogenetic relationship with flavonoid glucosyltransferases?

Amino Acid Sequence↗
PubMed1999

Cloning and expression of a cDNA encoding betanidin 5-O-glucosyltransferase, a betanidin- and flavonoid-specific enzyme with high homology to inducible glucosyltransferases from the Solanaceae.

Based on protein sequence data and RT-PCR, a full length cDNA encoding betanidin 5-O-glucosyltransferase (5-GT) was obtained from a cDNA library of Dorotheanthus bellidiformis (Burm.f.) N.E.Br. (Aizoaceae). 5-GT catalyses the transfer of glucose from UDP-glucose to the 5-hydroxyl group of the chromogenic betanidin. Betanidin and its conjugates, referred to as betacyanins, are characteristic fruit and flower pigments in most members of the Caryophyllales, which fail to synthesise anthocyanins. The 5-GT cDNA displayed homology to previously published glucosyltransferase sequences and exhibited high identity to sequences of several inducible glucosyltransferases of tobacco and tomato (Solanaceae). The open reading frame encodes a polypeptide of 489 amino acids with a calculated molecular mass of 55.24 kDa. The corresponding cDNA was expressed in Escherichia coli. The recombinant protein displayed identical substrate specificity compared to the native enzyme purified from D. bellidiformis cell suspension cultures. In addition to the natural substrate betanidin, ortho-dihydroxylated flavonols and flavones were glycosylated preferentially at the B-ring 4'-hydroxyl group. 5-GT is the first enzyme of betalain biosynthesis in plants, of which the corresponding cDNA has been cloned and expressed. The results are discussed in relation to molecular evolution of plant glucosyl- transferases.

Amino Acid Sequence↗
PubMed1980

Glucose and sucrose effects in the culture media on Streptococcus sanguis OMZ 9 glucosyltransferase inhibition by anti-glucosyltransferase antibodies.

An anti-glucosyltransferase serum was prepared against a purified enzyme of Streptococcus sanguis OMZ 9. Antibody fractions obtained after gel filtration on a Bio-Gel P200 column were used to study enzyme-antibody interaction in broth culture containing either sucrose or glucose, and to localize ultrastructurally the enzyme on thin sections of bacteria using labelled and unlabelled antibodies. The antibody fractions had no effect on bacterial growth in broth culture. A strong inhibition of insoluble and soluble polysaccharides synthesis was obtained in batch culture after a 24 hours incubation of bacteria with rides synthesis was obtained in batch culture after a 24 hours incubation of bacteria with antibodies. The GTF was localized at different cellular levels on bacteria grown in glucose but the ultrastructural method failed to localize GTF in sucrose grown cells.

Antibodies↗
PubMed1989

Glucan-binding domain of a glucosyltransferase from Streptococcus sobrinus: isolation of a 55-kilodalton peptide from a trypsin digest of glucosyltransferase prebound to insoluble glucan.

We isolated a glucan-binding domain of water-insoluble glucan synthase (GTF-I) of Streptococcus sobrinus B13. Mild trypsin digestion of GTF-I bound to a water-insoluble glucan (IG) produced one predominant large fragment (55 kilodaltons). The fragment was easily recovered in IG precipitate. The isolated fragment had the same degree of affinity to IG as did the native GTF-I but no glucan synthesis activity. By the same method, a similar 55-kilodalton fragment was protected for GTF-Sd but not for GTF-Si. Immunological comparisons using specific antisera against the purified glucan-binding fragment of GTF-I from strain B13 indicated that GTF-I and GTF-S have a distinct glucan-binding domain.

Antibodies, Bacterial↗
PubMed1968

Some Properties of Potato Tuber UDPGd-fructose-2-glucosyltransferase (E.C. 2.4.1.14) and UDPGd-fructose-6-phosphate-2-glucosyltransferase (E.C. 2.4.1.13).

Sucrose and sucrose 6-phosphate synthetase were isolated from potato tubers, partially purified and their properties studied. The sucrose synthetase showed optimum activity at 45 degrees and was inhibited competitively by ADP and some phenolic glucosides. The Ki's for these inhibitors were determined. Mg(2+) was found to activate this enzyme. Activity toward UDP-glucose or ADP-glucose formation was measured. The optimum conditions for sucrose and UDP-glucose formation were found to differ. The specificity for the glucosyl donor and acceptor were determined.The optimum conditions for sucrose 6-phosphate synthetase activity were studied. This enzyme was not inhibited by either ADP or phenolic glucosides; UDP-glucose was the only glucosyl donor for sucrose 6-phosphate formation.

Journal Article↗
PubMed1997

Molecular analysis of representative Streptococcus gordonii Spp phase variants reveals no differences in the glucosyltransferase structural gene, gtfG.

Streptococcus gordonii glucosyltransferase polymerizes sucrose to form glucans, which confer a hard, sucrose-promoted phenotype (Spp+) to colonies on sucrose agar plates. The glucosyltransferase structural gene, gtfG, is positively regulated by the upstream determinant, rgg. Strain Challis undergoes a spontaneous, reversible phase variation between high (Spp+) and low (Spp-) levels of glucosyltransferase activity. Representative strains were examined to gain insights into the basis of glucosyltransferase phase variation. Western blots indicated that the level of glucosyltransferase activity was related to the amount of extracellular glucosyltransferase protein produced by Spp- and Spp+ strains. The nucleotide sequence of rgg and gtfG of the Spp- strain CH97 was found to be identical to that of the Spp+ parent, indicating that DNA differences in these regions are not the basis for glucosyltransferase phase variation. Indeed, 13C-NMR spectroscopy suggested that glucans synthesized by strain CH97 glucosyltransferase were similar to those synthesized by glucosyltransferase of the Spp+ parental strain, indicating a quantitative rather than qualitative change. However, one Spp- strain, CH1C1, had a point mutation in rgg; replacement of the parent rgg with the CH1C1 allele resulted in decreased levels of glucosyltransferase protein and activity. The results indicate that glucosyltransferase phase variation can occur in more than one way, and suggest that glucosyltransferase regulation may involve distally located regulatory gene(s) that affect rgg and/or gtfG expression.

Alleles↗
PubMed1976

Regulation and extracellular glucosyltransferase production and the relationship between extracellular and cell-associated activities in Streptococcus mutans.

The regulation of extracellular glucosyltransferase production in Streptococcus mutans GS-5 has been studied using a chemically defined medium. Most of the glucosyltransferase activity produced by cells grown in the chemically defined medium was extracellular, in contrast with the distribution between cell-associated and extracellular glucosyltransferase activity when cells were grown in complex medium. The production of extracellular glucosyltransferase activity coincided with the logarithmic growth phase, and further accumulation ceased when glucose was exhausted from the medium. Accumulation of extracellular glucosyltransferase activity was inhibited immediately by chloramphenicol and rifamycin, added either at the beginning of growth or during mid-logarithmic growth. Low concentrations of chloramphenicol inhibited both cellular protein synthesis and the accumulation of extracellular glucosyltransferase activity to the same extent, indicating a close coupling between glucosyltransferase synthesis and secretion. Experiments using cell lysates showed that no intracellular accumulation of glucosyltransferase activity occurred in the presence of the inhibitors and that the intracellular activity is very low relative to the cell-surface activity. The utilization of cells depleted of cell-associated glucosyltransferase activity indicated that most of the cell-associated glucosyltransferase activity does not act as a precursor for the extracellular enzyme. Sugar analogue inhibitors of glycoprotein synthesis did not have any specific effects on the synthesis or secretion of extracellular glucosyltransferase activity.

Bacterial Proteins↗
PubMed1996

Purification and properties of extracellular glucosyltransferase from Streptococcus bovis.

Eight Streptococcus bovis strains were classified into 3 types on the basis of isoelectric point (pI) and molecular mass (M(r)) of extracellular glucosyltransferase. Strains ATCC 9809, 35034 and 43143 produced glucosyltransferase of pI 3.7 and M(r) 165 kDa; strains ATCC 15351, 27960 and 33317 produced glucosyltransferase of pI 4.1 and M(r) 140 kDa; strains ATCC 43085 and 43144 did not produce any glucosyltransferase. The glucosyltransferase form S. bovis 9809 was purified by Bio-Gel hydroxyapatite chromatography and DEAE-Toyopearl chromatography. The S. bovis 9809 glucosyltransferase was immunologically identical with the other 5 S. bovis glucosyltransferases and not related to mutants streptococcal glucosyltransferases. The specific activity, the optimum pH and the Km value for sucrose were 17.9 U/mg protein, 6.0 and 5.0 mM, respectively. The first 11 N-terminal amino acid residues of the glucosyltransferases were DETSAVTLTRE, and the region was hydrophilic. The glucosyltransferases from S. bovis 9809 and 3317 synthesized from sucrose 1, 6-alpha-D-glucan with 9 and 2 mol%, 1, 3, 6-alpha-branched glucose, respectively.

Amino Acid Sequence↗
PubMed1978

Production of extracellular and cell-associated glucosyltransferase activity by Streptococcus mutans during growth on various carbon sources.

The production of extracellular and cell-associated glucosyltransferase activity by Streptococcus mutans strain GS-5 was examined during growth on various carbon sources in a chemically defined medium. S. mutans cells produced glucosyltransferase activity only during logarithmic growth when glucose, fructose, mannitol, or sorbitol was the sole carbon source. Cells growing on mannitol or sorbitol produced approximately half as much extracellular glucosyltransferase activity as cells growing on glucose, although the proportions of the glucosyltransferase activity capable of synthesizing insoluble glucans were similar. Cells growing on fructose produced slightly more extracellular glucosyltransferase activity than cells grown on glucose, yet the proportion of the glucosyltransferase activity capable of synthesizing insoluble glucans was again similar to glucose cultures. S. mutans cells growing in the presence of both glucose and mannitol displayed diauxic growth and initial preferential utilization of glucose. Glucosyltransferase enzyme production occurred only during the phases of cell growth in the presence of the two carbon sources. The cell-associated glucosyltransferase activities of glucose-, fructose-, mannitol-, and sorbitol-grown cells were relatively low, yet all the cells were capable of adherence to glass in the presence of sucrose. When glucose-containing cultures of S. mutans were supplemented with sucrose, extracellular glucosyltransferase activity first became cell associated and then appeared to become inactivated, presumably due to the accumulation of insoluble glucans.

Carbohydrate Metabolism↗
PubMed1990

Characterization of a protein:glucosyltransferase activity in human platelets.

Human platelets exhibited significant glucosyltransferase activity, that transfer [14C]glucose from UDP-Glc to an endogenous protein acceptor. The enzyme protein:glucosyltransferase responsible for the catalysis was characterized and compared with glycogen:glucosyltransferase. We describe a partial separation of both activities, the ratio of protein:glucosyltransferase/glycogen:glucosyltransferase varied from 7:1 in a crude homogenate of platelets to 36:1 in the Sephadex G-100 column. This procedure failed to separate the protein:glucosyltransferase from its endogenous acceptor. Glucosylation of protein demonstrated dependence with respect to time and both protein and UDP-Glc concentration, and was saturated by very low concentration of donor and acceptor substrates. It was inhibited 76% by 5 mM Mn2+ concentration and was activated 23 and 11% by 5 mM concentrations of Ca2+ and Mg2+, respectively. With respect to glycogen:glucosyltransferase, when the effect of time, protein, and substrate concentration were determined under identical conditions, it did not show the same dependence. At 5 mM concentration, Mn2+, Ca2+, and Mg2+ were activators of the enzyme 43, 80, and 200%, respectively. On the basis of these characteristics, we conclude that the synthesis of glucoprotein and glycogen are catalyzed by two distinct enzymes. Addition of exogenous glycogen (range 0.002-1%) inhibited the protein:glucosyltransferase, whereas at 0.001-0.007% concentration it was acceptor substrate for glycogen:glucosyltransferase activity. At higher concentrations this activity was strongly inhibited. The concentration of glycogen in platelets could play a regulatory role in forming the glucoprotein and the glycogen molecules.

Blood Glucose↗
PubMed2002

Genetic analysis of the rgg-gtfG junctional region and its role in Streptococcus gordonii glucosyltransferase activity.

Glucans synthesized by glucosyltransferase enzymes of oral streptococci facilitate bacterial accumulation on surfaces. The Streptococcus gordonii glucosyltransferase gene, gtfG, is positively regulated by rgg, which encodes a putative cytoplasmic protein. The gtfG promoter and ribosomal binding sequences are located within a DNA inverted repeat immediately downstream of rgg. Polycistronic rgg-gtfG as well as rgg- and gtfG-specific transcripts are associated with this chromosomal region. Previous studies have shown that the rgg product acts in trans near the gtfG promoter to increase the level of gtfG transcript, but it does not affect the level of rgg-gtfG transcript. To further analyze regulation by rgg, a series of strain Challis derivatives was constructed and glucosyltransferase activities were determined. Strains in which rgg was separated from gtfG by integrated vector sequences had decreased levels of glucosyltransferase activity; plasmid-borne rgg could not increase activity to parental levels. As expected, strains with chromosomal deletions involving the rgg structural gene and either the rgg or gtfG promoter also showed decreased glucosyltransferase activity. Plasmid-borne rgg could increase glucosyltransferase activity only in strains which had a 36-bp chromosomal region beginning 72 nucleotides upstream of the gtfG transcriptional start site. Results suggest that these nucleotides, located within the 3' end of rgg, are necessary, either by direct involvement in binding or by indirectly affecting secondary structure, for Rgg to increase glucosyltransferase activity. Surprisingly, the presence of the rgg promoter upstream of this 36-bp region significantly increased the effects of plasmid-borne rgg. Implications for glucosyltransferase regulation and applicability to other rgg-like determinants are considered.

Bacterial Proteins↗
PubMed1998

Cloning and characterization of Vitis vinifera UDP-glucose:flavonoid 3-O-glucosyltransferase, a homologue of the enzyme encoded by the maize Bronze-1 locus that may primarily serve to glucosylate anthocyanidins in vivo.

We report here the cloning and optimized expression at 16 degrees C and the characterization of a Vitis vinifera UDP-glucose:flavonoid 3-O-glucosyltransferase, an enzyme responsible for a late step in grapevine anthocyanin biosynthesis. The properties of this and other UDP-glucose:flavonoid 3-O-glucosyltransferases, homologues of the product encoded by the maize Bronze-1 locus, are a matter of conjecture. The availability of a purified recombinant enzyme allowed for the unambiguous determination of the characteristics of a flavonoid 3-O-glucosyltransferase. Kinetic analyses showed that kcat for glucosylation of cyanidin, an anthocyanidin substrate, is 48 times higher than for glucosylation of the flavonol quercetin, whereas Km values are similar for both substrates. Activity toward other classes of substrates is absent. Cu2+ ions strongly inhibit the action of this and other glucosyltransferases; however, we suggest that this phenomenon in large part is due to Cu2+-mediated substrate degradation rather than inhibition of the enzyme. Additional lines of complementary biochemical data also indicated that in the case of V. vinifera, the principal, if not only, role of UDP-glucose:flavonoid 3-O-glucosyltransferases is to glucosylate anthocyanidins in red fruit during ripening. Other glucosyltransferases with a much higher relative activity toward quercetin are suggested to glucosylate flavonols in a distinct spatial and temporal pattern. It should be considered whether gene products homologous to Bronze-1 in some cases more accurately should be referred to as UDP-glucose:anthocyanidin 3-O-glucosyltransferases.

Amino Acid Sequence↗
PubMed1980

Interaction of glucosyltransferase from Streptococcus mutans with various glucans.

Cell-free glucosyltransferase of Streptococcus mutans strain B13 (serotype d) exclusively synthesized water-insoluble glucan from sucrose. The insoluble glucan possessed strong glucan-associated glucosyltransferase activity even after extensive washing and lyophilization. Furthermore, cell-free glucosyltransferase became bound to heat-treated water-insoluble glucan or to heat-treated S. mutans B13 cells grown in Todd Hewitt broth, and the resulting glucan and cells adhered to a glass surface in the presence of exogenous sucrose. No other water-insoluble glucans bound significant quantities of glucosyltransferase. Glucan synthesis by free or glucan-bound glucosyltransferase was stimulated by low concentrations (1 to 5 mg ml-1) of isomaltose or water-soluble dextrans of various molecular weights, but higher concentrations (10 mg ml-1) inhibited glucan synthesis. The glucan synthesized in the presence of primer dextrans exhibited a reduced ability to adhere to a glass surface. Certain sugars such as maltose and fructose significantly lowered the yield of insoluble glucans. Preincubation of glucosyltransferase with the low molecular weight dextran T10 increased subsequent binding to S. mutans B13 insoluble glucan, whereas preincubation with higher molecular weight dextrans significantly inhibited the glucosyltransferase binding.

Adhesiveness↗
PubMed1997

Separation by FPLC chromatofocusing of UDP-glucosyltransferases from three developmental stages of Drosophila melanogaster.

Variation of UDP-glucosyltransferase activity, during Drosophila melanogaster development, was analyzed. The endogenous metabolite xanthurenic acid and the xenobiotic compounds 1-naphthol and 2-naphthol were used as substrates. Developmentally regulated differences were observed for the three substrates, suggesting the presence of UDP-glucosyltransferase isoenzymes. This was further confirmed by FPLC chromatofocusing on a Mono P column: seven peaks of UDP-glucosyltransferase activity (pHs: > or = 6.3, 5.8, 5.5, 4.9, 4.5, 4.2, < or = 4.0) with either single or overlapping substrate specificity were detected. A single xanthurenic acid:UDP-glucosyltransferase activity (pl 5.8) was found throughout development. In contrast, a gradual increase in the number of 2-napthol:UDP-glucosyltransferase-isoenzymes (pl from 6.3 to 4.0) was observed during development, whereas no isoenzymes specific for 1-naphthol were resolved. Based on the distribution and substrate specificity of the eluted peaks in the three developmental stages analyzed, the presence of seven or possibly eight UDP-glucosyltransferase isoenzymes is proposed.

Animals↗