Showing papers on "Melibiose published in 1993"
TL;DR: It is shown that most of human IgM antibodies present in the serum of healthy donors and reactive with pig cells react with galactose in an (alpha 1-3) linkage with Galactose--i.e., Gal(alpha 1,3)Gal.
Abstract: A major problem with pig-to-human-tissue xenograft studies is that humans have natural antibodies to pig cells; these antibodies would cause hyperacute rejection if pig tissues were xenografted to humans. Here we show that most of human IgM antibodies present in the serum of healthy donors and reactive with pig cells react with galactose in an (alpha 1-3) linkage with galactose--i.e., Gal(alpha 1-3)Gal. Absorption studies demonstrated that the antibodies detected the same or similar epitopes on the surface of pig erythrocytes, blood and splenic lymphocytes, and aortic endothelial cells (EC). The antibodies were sensitive to 2-mercaptoethanol (2ME) treatment, did not bind to protein A or G, and were present in the high molecular weight fraction of serum; they are clearly IgM antibodies. Further, the antibodies did not react with human ABO blood group substances and are not related to human blood group A or B, which carry a terminal galactose. The reaction of human serum with pig erythrocytes was specifically inhibited by mono- and disaccharides: D-galactose, melibiose, stachyose, methyl-alpha-D-galactopyranoside, and D-galactosamine but not by D-glucose or methyl-beta-D-galactopyranoside; demonstrating that the reaction is with galactose in an alpha and not a beta linkage. A cDNA clone encoding the murine alpha-1,3-galactosyltransferase (which transfers a terminal galactose residue with an (alpha 1-3) linkage to a subterminal galactose) was isolated by polymerase chain reaction (PCR), cloned, and transfected into COS cells, which are of Old World monkey origin and, like humans, do not express Gal(alpha 1-3)Gal. After transfection, COS cells became strongly reactive with human serum and with IB4 lectin [which reacts only with Gal(alpha 1-3)Gal]; this reactivity could be removed by absorption with pig erythrocytes. As most of the antibody reacting with pig cells can be removed by absorption with either melibiose or Gal(alpha 1-3)Gal+ COS cells, most of these react with Gal(alpha 1-3)Gal. These findings provide the basis for genetic manipulation of the pig alpha-1,3-galactosyltransferase for future transplantation studies.
611 citations
TL;DR: It is concluded that this mutant alpha-galactosidase gene, Q279E (279Gln-->Glu), found in an atypical variant of Fabry disease, is posttranslationally inactivated under the neutral conditions in the cells.
129 citations
TL;DR: Binding studies of a high affinity ligand on de-energized membrane vesicles indicate that these modified transporters retain the ability to bind the alpha-galactosides NPG or melibiose and the beta-Galactoside TMG and exhibit a Na(+)-independent sugar-binding phenotype.
95 citations
TL;DR: Trichoderma reesei RUT C-30 formed an extracellular alpha-galactosidase when it was grown in a batch culture containing lactose or locust bean gum as a carbon source and its action on galactomannan was increased by the presence of beta-mannanase.
Abstract: Trichoderma reesei RUT C-30 formed an extracellular alpha-galactosidase when it was grown in a batch culture containing lactose or locust bean gum as a carbon source. Short-chain alpha-galactosides (melibiose, raffinose, stachyose), as well as the monosaccharides galactose, dulcitol, arabinose, and arabitol, also induced alpha-galactosidase activity both when they were used as carbon sources (at a concentration of 1%) in batch cultures and in resting mycelia (at concentrations in the millimolar range). The addition of 50 mM glucose did not affect the induction of alpha-galactosidase formation by galactose. alpha-Galactosidase from T. reesei RUT C-30 was purified to homogeneity from culture fluids of galactose-induced mycelia. The active enzyme was a 50 +/- 3-kDa, nonglycosylated monomer which had an isoelectric point of 5.2. It was active against several alpha-galactosides (p-nitrophenyl-alpha-D-galactoside, melibiose, raffinose, and stachyose) and galactomannan (locust bean gum) and was inhibited by the product galactose. It released galactose from locust bean gum and exhibited synergism with T. reesei beta-mannanase. Its activity was optimal at pH 4, and it displayed broad pH stability (pH 4 to 8). Its temperature stability was moderate (60 min at 50 degrees C resulted in recovery of 70% of activity), and its highest level of activity occurred at 60 degrees C. Its action on galactomannan was increased by the presence of beta-mannanase. Images
91 citations
TL;DR: Zymobacter palmae gen. nov., sp.
Abstract: Zymobacter palmae gen. nov., sp. nov. was proposed for a new ethanol-fermenting bacterium that was isolated from palm sap in Okinawa Prefecture, Japan. The bacterium is gram-negative, facultatively anaerobic, catalase-positive, oxidase-negative, nonspore-forming and peritrichously flagellated. It requires nicotinic acid for growth. It ferments hexoses, α-linked di- and tri-saccarides, and sugar alcohols (fructose, galactose, glucose, mannose, maltose, melibiose, saccharose, raffinose, mannitol and sorbitol). Fifteen percent of maltose in broth medium is effectively fermented, whereas glucose with a concentration higher than 10% delayed growth initiation and decreased growth rates. Maltose is fermented to produce ethanol and CO2 with a trace amount of acids. Approximately 2 mol of ethanol are produced from 1 mol moiety of hexose of maltose. The organism possesses ubiquinone-9. The G+C content of the DNA is 55.8+-0.4 mol%. Major cellular fatty acids were palmitic and oleic acids and cyclopropanic acid of C19:0. Characteristic hydroxylated acid was 3-hydroxy dodecanoic acid. The bacterium is distinct from other ethanol-fermenting bacteria belonging to the genera Zymomonas Kluyver and van Niel 1936 and Saccharobacter Yaping et al. 1990 with respect to chemotaxonomic and other phenotypic characters to warrant to compose a new genus and a new species. The type strain is strain T109 (= IAM 14233).
85 citations
Patent•
05 Nov 1993
TL;DR: A material which has the ability to effect it's passage, at least in part, and the ability of transport other materials through the blood-brain barrier which includes any one or more pure sugars or pure amino sugars from the group consisting of meso erythritol, zylitol, D+ galactose, D(+) lactose, dulcitol, myo-insoitol, L(-) fructose, D
Abstract: A material which has the ability to effect it's passage, at least in part, and the ability to transport other materials through the blood-brain barrier which includes any one or more pure sugars or pure amino sugars from the group consisting of meso erythritol, zylitol, D(+) galactose, D(+) lactose, D(+) xylose, dulcitol, myo-insoitol, L(-) fructose, D(-) mannitol, sorbitol, D(+) glucose, D(+) arabinose, D(-) arabinose, celloboise, D(+) maltose, D(+) raffinose, L(+)rhamnose, D(+) melibiose, D(-) ribose, adonitol, D(+) arabitol, L(-) arabitol, D(+) fucose, L(-) fucose, D(-) lyxose, L(+) lyxose, L(-) lyxose, D(+) glucosamine, D mannosamine, and D galactosamine; and any one or more amino acids from the group consisting of arginine, asparagine, aspartic acid, cysteine, glutamic acid, glycine, histidine, leucine, methionine, phenylalanine, proline, serine, threonine, glutamine, lysine, tryptophan, tyrosine, valine, and taurine. For use in the research or treatment of a subject that material is combined with one or more of the substances beta carotene, xanthophyll, lecithin, calcium, somatostatin, vasopressin, endorphin, enkephalin, acetyl-L-carnitine, GABA, dynorphin, L-tryptophan, choline, thiamine, pyridoxine, niacin, L-arginine, hydroxyproline, NGF, methionine, cystine, potassium, phosphorus, chlorine, sodium, vitamins A, B, C, D and E, tricalcium phosphate, omega 3 and omega 6 both of which are high linolenic acids, oats, rice, apple fiber, acidophilus, and selenium.
72 citations
TL;DR: The results provide additional evidence indicating that manipulation of some of these Asp in the membrane-spanning segments of mel permease alters its cationic selectivity properties and also the existence of a possible gating mechanism that may contribute the obligatory coupling of cosubstrate flows by the symporter.
67 citations
TL;DR: Most of the glucose kinase activity was observed with the pellet fraction obtained by centrifugation, suggesting an association of the enzyme with the bacterial cell envelope, and the enzyme is a glucokinase rather than a hexokinase.
48 citations
TL;DR: There is no universal Na+ recognition site for all the sugar substrates, instead different parts of the carrier seem to participate in cation recognition for different sugar substrate.
47 citations
TL;DR: Electrokaryotyping showed that all of the S. pastorianus and S. bayanus strains studied had one MEL locus and most of the Mel+ S. cerevisiae strains had one to seven loci containing MEL sequences, which could be divided into two categories on the basis of hybridization to MEL1.
Abstract: In Saccharomyces spp. the ability to use melibiose depends on the presence of a MEL gene encoding alpha-galactosidase. We used two cloned MEL genes as probes to characterize the physical structure and chromosomal location of the MEL genes in several industrial and natural Mel+ strains of Saccharomyces cerevisiae, Saccharomyces pastorianus, and Saccharomyces bayanus. Electrokaryotyping showed that all of the S. pastorianus strains and most of the S. bayanus strains studied had one MEL locus. The MEL gene in S. bayanus strains was similar but not identical to the S. pastorianus MEL gene. Mel+ S. cerevisiae strains had one to seven loci containing MEL sequences. The MEL genes of these strains could be divided into two categories on the basis of hybridization to MEL1, one group exhibiting strong hybridization to MEL1 and the other group exhibiting weak hybridization to MEL1. In S. pastorianus and S. bayanus strains, the MEL gene was expressed as a single 1.5-kb transcript, and the expression was galactose inducible. In some S. cerevisiae strains, the MEL genes were expressed even without induction at fairly high levels. Expression was usually further induced by galactose. In two strains, CBS 5378 and CBS 4903, expression of the MEL genes was at the same level without induction as it was in most other strains with induction. In all S. cerevisiae strains, irrespective of the number of MEL genes, mRNA of only one size (1.6 kb) was observed.
39 citations
TL;DR: It was concluded that Lys-319 interacts with Glu-269 and Asp-240 probably as salt bridges.
TL;DR: The enzymatic characteristics and the cross reactivity of the antibodies suggest that alpha-galactosidases isolated from the two sources were the same enzyme, which is a multimeric enzyme of 370 kDa composed of four monomers of 87 kDa and a pI of 6.3.
Abstract: alpha-Galactosidases from mycelial extract and culture filtrate of Aspergillus nidulans have been purified to homogeneity and utilised to obtain polyclonal antibodies anti-alpha-galactosidase. The enzymatic characteristics and the cross reactivity of the antibodies suggest that alpha-galactosidases isolated from the two sources were the same enzyme. Thus, A. nidulans synthesized and secreted only one enzymatic form of alpha-galactosidase which is a multimeric enzyme of 370 kDa composed of four monomers of 87 kDa and a pI of 6.3. The optimum temperature of activity was 50 degrees C and the optimum pH 4-5. The enzyme was stable over a wide range of pH but quite unstable to temperature. alpha-Galactosidase of A. nidulans is a very specific enzyme, it is active only on p-nitrophenyl-alpha-D-galactoside (PNPG), melibiose and raffinose. When PNPG was utilised as substrate melibiose, raffinose, galactose and glucose were competitive inhibitors of the activity.
TL;DR: The cloned msm operon was cloned into the chromosomes of two heterologous streptococcal strains, Streptococcus gordonii Challis and StrePTococcus anginosus Is57, and the newly constructed recombinants gained the ability to ferment all of these sugars.
Abstract: The multiple sugar metabolism (msm) operon of Streptococcus mutans is responsible for the uptake and metabolism of a variety of sugars. In order to further characterize the substrate specificities of the transport system, a 12-kb region of DNA containing the entire msm operon was cloned, via a novel two-step integration strategy, into the chromosomes of two heterologous streptococcal strains, Streptococcus gordonii Challis and Streptococcus anginosus Is57, as well as the chromosome of a natural isolate of S. mutans with a deletion of the msm region. These strains are unable to transport or ferment melibiose, raffinose, or isomaltosaccharides, but the newly constructed recombinants gained the ability to ferment all of these sugars. The S. gordonii Challis construct containing msm was shown to transport radiolabelled melibiose, raffinose, isomaltotriose, and isomaltotetraose, and the transport function was also subjected to induction by raffinose, an inducer of the msm operon in S. mutans. The results confirm the role of the msm operon in the transport and metabolism of melibiose, raffinose, and isomaltosaccharides.
TL;DR: In this paper, the reaction of aldose oligosaccharides with aqueous ammonium hydrogen carbonate was revised and optimized for gram scale preparation of glycosylamines, using lactose, cellobiose, maltose, and melibiose as model compounds.
TL;DR: Soluble invertase (β-fructosidase EC 3.2.1.256) was purified to apparent homogeneity from ripe tomato using conventional procedures and revealed significant amino acid sequence similarity with carrot, yeast, and bacterial invertases.
TL;DR: Two Ca(2+)-dependent lectins were purified from the sea cucumber Stichopus japonicus and it is suggested that SJL-II may have high specificity for particular complex carbohydrate(s) on the surface of rabbit erythrocytes.
Abstract: Two Ca(2+)-dependent lectins were purified from the sea cucumber Stichopus japonicus by affinity chromatography on lactosyl-Sepharose 4B and ion-exchange chromatography on Q-Sepharose. Their molecular masses were estimated to be 13kDa (SJL-I) and 15 kDa (SJL-II) on SDS-PAGE. SJL-I agglutinated rabbit erythrocytes as well as human A, B, and O-type erythrocytes, but SJL-II agglutinated only rabbit erythrocytes. Hemagglutination by SJL-I was competitively inhibited by N-acetyl-D-galactosamine and galactose-containing carbohydrates. On the other hand, only lactose, melibiose, and raffinose gave weak inhibition of hemagglutination by SJL-II, suggesting that SJL-II may have high specificity for particular complex carbohydrate(s) on the surface of rabbit erythrocytes. SJL-II was activated at ten times lower Ca2+ concentration than SJL-I. Both lectins lost activity in acidic pH, while SJL-I appeared more stable down to pH 4.5.
TL;DR: In this article, the expression of other genes is affected by the mutation and what the physiological link is between them, and the authors examined three S. salivarius IIILMan-defective mutants (strains A37, B31 and G29) and the parental strain using two-dimensional gel electrophoresis after growth of the cells on a variety of sugars.
TL;DR: Up to 66% of the viable microspores were able to divide and many of these developed into microcalli in the basal medium complemented with melibiose, maltose, melezitose, raffinose, Ficolls, PEG or a combination of Ficoll with PEG.
Abstract: Barley microspores were viable when cultured in a sugarless medium. Adding 2g of glucose to 1l of this medium resulted in a significant reduction in the frequency of viable microspores. The frequency of viable microspores was further reduced when 50g of cellobiose, glucose, maltose, melezitose, raffinose or sucrose were added to 1l of the culture medium containing 2g/l glucose. Adding 50g of melibiose, Ficoll, polyethylene glycol (PEG) or a combination 50g each of Ficoll and PEG to 1I of the medium containing 2g/l glucose had very little effect on the viability of the microspores.
01 Jan 1993
TL;DR: Trichoderma reesei RUTC-30 formed anextracellular a-galactosidase whenit was grown inabatchculture containing lactose orlocust beangumasacarbonsource, and this enzymatic hydrolysis requires theconcerted action of the following hydrolytic enzymes: endo-1,4-1-D-mannanase (EC3.2.1.78),
Abstract: Trichoderma reesei RUTC-30formed anextracellular a-galactosidase whenitwasgrowninabatchculture containing lactose orlocust beangumasacarbonsource. Short-chain a-galactosides (melibiose, raffinose, stachyose), aswellasthemonosaccharides galactose, dulcitol, arabinose, andarabitol, alsoinduced at-galactosidase activity bothwhentheywereusedascarbon sources (ataconcentration of1%)inbatch cultures andin resting mycelia (atconcentrations inthemillimolar range). Theaddition of50mM glucose didnotaffect the induction ofac-galactosidase formation bygalactose. a-Galactosidase fromT.reesei RUT C-30waspurified to homogeneity fromculture fluids ofgalactose-induced mycelia. Theactive enzymewasa 50 ± 3-kDa, nonglycosylated monomerwhichhadanisoelectric point of5.2.Itwasactive against several a-galactosides (p-nitrophenyl-t-D-galactoside, raffinose, andstachyose) andgalactomannan (locust beangum)and wasinhibited bytheproduct galactose. Itreleased galactose fromlocust beangumandexhibited synergism with T.reesei 1-mannanase. Itsactivity wasoptimal atpH4,anditdisplayed broadpH stability (pH4to8).Its temperature stability wasmoderate (60minat50°Cresulted inrecovery of70%oofactivity), andits highest level ofactivity occurred at60°C. Itsaction ongalactomannan wasincreased bythepresence of13-mannanase. Hemicelluloses arethesecond mostabundant polysaccharides innature, andtheyseemtobelinked tolignin inwood (23). Themajor constituents ofhemicellulose arethehetero1,4-0-D-xylans andthehetero-1,4-,B-D-mannans (galactoglucomannansandglucomannans). Whileheteroxylans are found mainly ingrasses, cereals, andhardwoods, P-mannans aremoreabundant insoftwoods (8,23). Thebiotechnologicalinterest inthehydrolysis ofhemicelluloses forthepulp andpaperindustry andthefeedstock industry hasrecently revived interest intheenzymology ofhemicellulose degradation. Inthecaseofgalactomannans, this enzymatic hydrolysis requires theconcerted action ofthefollowing hydrolytic enzymes: endo-1,4-1-D-mannanase (EC3.2.1.78),
01 Jan 1993
TL;DR: Pourcher et al. as discussed by the authors investigated the effect of substitutions on the cationic selectivity and coupling properties of me1 permease, H+melibiose coupled transport, coupling between H' and melibiose movements, sugar counterflow, and zero-trans sugar efflux by the mutant permeases.
Abstract: Individual substitution of Cys or Asn for Asp-31, Asp-51, Asp-55, or Asp-120, distributed in different membrane spanning segments of the NHz-terminal domain of melibiose (rnel) permease partially or completely inactivates Na’-linked sugar transport and stimulation of sugar binding on me1 permease by Na+ ions (Pourcher, T., Zani, M.-L., and Leblanc, G. (1993) J. Biol. Chem. 268, 3209-3215). To investigate further the effect of these substitutions on the cationic selectivity and coupling properties of me1 permease, H+-melibiose coupled transport, coupling between H’ and melibiose movements, sugar counterflow, and zero-trans sugar efflux by the mutant permeases were analyzed. The results provide additional evidence indicating that manipulation of some of these Asp in the membrane-spanning segments of me1 permease alters its cationic selectivity properties. The results also indicate that the individual mutations diversely affect me1 permease-coupling properties. For example, only permease with Asn in place of Asp-31 or Cys in place of Asp-51 retains the capacity to actively transport melibiose. On the other hand, replacing Asp-55 by Cys produces uncoupling of cosubstrate flows by the carrier but does not hamper sugar translocation. These and other features of the mutant permeases are used to discuss the relative participation of Asp-31, Asp-51, Asp-55, or Asp-120 to the me1 symport mechanism and to its ionic selectivity and also the existence of a possible gating mechanism that may contribute the obligatory coupling of cosubstrate flows by the symporter.
TL;DR: To isolate the major carbohydrate-binding proteins in pooled normal chicken sera, affinity chromatographies on different affinity gels were carried out and they were electrophoretically and antigenically found to be mainly IgM and IgG.
Abstract: To isolate the major carbohydrate-binding proteins in pooled normal chicken sera, affinity chromatographies on different affinity gels were carried out. From the results obtained, normal chicken sera were found to contain serum proteins which were Ca2+-dependently and -independently reactive with mannose, N-acetylglucosamine, N-acetylgalactosamine, L-fucose, melibiose, lactose, unsubstituted Sepharose 4B, and SeaKem HE agarose. They were electrophoretically and antigenically found to be mainly IgM and IgG.
TL;DR: The results raise the possibility that nonreducing terminal α-D-galactosyl-containing glycoproteins composed of heterogeneous carbohydrate chains may be present on the surface of a number of different murine tumor cells as well as on human type B erythrocytes.
Abstract: A novel 36kDa rhamnose-binding lectin isolated from Plecoglossus altivelis roe (PA 36), a probe for L-rhamnose and α-D-galactosyl nonreducing termini, bound to and agglutinated murine tumor cells rather than human type B erythrocytes. PA 36 was purified by DEAE-cellulose ion exchange and rhamnose-Sepharose affinity chromatography. The most effective saccharide in the agglutination inhibition assay was L-rhamnose. The α-D-galactosyl containing saccharides, such as melibiose, raffinose and stachyose, were more effective than the β-D-galactosyl containing saccharide, lactose. Lectin binding glycoproteins were determined by SDS-PAGE and blotting, followed by reaction with horseradish peroxidase-labeled PA 36. The glycoproteins ranging in molecular weight from 66, 000 to 72, 000 and deriving from murine tumor cells and bands 4.1 and 4.2 deriving from human type B erythrocytes were PA 36-binding glycoproteins. These results raise the possibility that nonreducing terminal α-D-galactosyl-containing glycoproteins composed of heterogeneous carbohydrate chains may be present on the surface of a number of different murine tumor cells as well as on human type B erythrocytes.
01 Jan 1993
TL;DR: A species of yeast was isolated from the intestines of rainbow trout Onco rhynchus mykiss fed with pelleted diets in two different aquaculture stations and found to multiply by budding, not to form spore and any pigment and identified as Candida sp.
Abstract: A species of yeast was isolated from the intestines of rainbow trout Onco rhynchus mykiss fed with pelleted diets in two different aquaculture stations. The yeast isolates were found to multiply by budding, not to form spore and any pigment and identified as Candida sp. The yeast isolates fermented glucose, galactose, sucrose, fructose, inulin and trehalose but not lactose, mannitol, malt ose, inositol, melibiose, cellobiose and starch. The isolates grew poorly on Z-AII agar without glucose, whereas they grew very well on Z-AII agar with glucose (ZAG agar). The representative strain Y91-01 grew in a temperature range of 13 to 34X3, in a pH range of 2 to 9, and in a NaCl concentration range of 0 to 7%. Strain Y91-01 required biotin as incubated in glucose-(NH4)2S04 medium. The total lipids extracted from strain Y91-01 cells contained Ci6:i, Ci6:o, Cw:i and Ci8:o as major fatty acids.
TL;DR: The α‐galactosidase activities of 11 strains of Leuconostoc mesenteroides grown on glucose, lactose or raffinose were determined, and apparent fermentation yields with raffInose‐component sugars complied with heterofermentation theory, except for sucrose, where there was a 40% deficit in fermentation products.
Abstract: The α-galactosidase activities of 11 strains of Leuconostoc mesenteroides subsp. mesenteroides grown on glucose, lactose or raffinose were determined. The inductive effects of lactose and raffinose differed depending on the strain. In four of the strains, α-galactosidase activity of cells grown on lactose was higher than that of cells grown on raffinose, while the reverse was true for one other strain. The study of two strains exhibiting a different behaviour was extended to all raffinose-component sugars: melibiose, sucrose, glucose, galactose and fructose. The apparent fermentation yields with raffinose-component sugars complied with heterofermentation theory, except for sucrose, where there was a 40% deficit in fermentation products. Raffinose hydrolysis enzymes (α-galactosidase and β-fructosidase) underwent a catabolic repression by glucose. Growth on raffinose was considerably stimulated if the inoculum was first grown on melibiose or raffinose (induction of α-galactosidase).
TL;DR: The native lactose repressor from Escherichia coli and two single-point mutants, W220Y and W201Y, were investigated using low-temperature phosphorescence and optical detection of magnetic resonance (ODMR) spectroscopy, and the triplet-state properties of tryptophans 201 and 220 were obtained independently.
Abstract: The native lactose repressor from Escherichia coli (Lac Rep) and two single-point mutants, W220Y and W201Y, were investigated using low-temperature phosphorescence and optical detection of magnetic resonance (ODMR) spectroscopy. Emission from two tryptophan residues was evident in the phosphorescence spectrum of native Lac Rep at 77 K. Using the single-point mutants, the triplet-state properties of tryptophans 201 and 220 were obtained independently. Trp 220 was characterized as a partially solvent-exposed residue (0,0 band centered at 409.5 nm), while tryptophan 201 exhibited the properties of a buried residue (0,0 band centered at 413.5 nm). Both single-point mutant proteins experienced changes in tryptophan triplet-state properties as a result of binding either of two inducer sugars: isopropyl beta-D-thiogalactoside, a monosaccharide, or melibiose, a disaccharide. Putative singlet-singlet energy transfer from tryptophan 220 to tryptophan 201 was also investigated, but the quantitative results must be viewed with some caution.
01 Jan 1993
TL;DR: Results confirm the role of the multiple sugarmetabolism operon inthetransport and metabolism of melibiose, raffinose, andisomaltosaccharides in the transport andabolism of Streptococcus mutans.
Abstract: Themultiple sugarmetabolism (msm)operonofStreptococcus mutansisresponsible fortheuptake and metabolism ofavariety ofsugars.Inorder tofurther characterize thesubstrate specificities ofthetransport system, a 12-kbregion ofDNA containing theentire msm operonwas cloned, viaa novel two-step integration strategy, intothechromosomes oftwoheterologous streptococcal strains, Streptococcus gordonii Challis and Streptococcus anginosus Is57, aswell asthechromosome ofanatural isolate ofS.mutanswithadeletion ofthe msm region. Thesestrains areunable totransport orferment melibiose, raffinose, orisomaltosaccharides, but thenewlyconstructed recombinants gained theability toferment allofthese sugars.TheS.gordonii Challis construct containing msm was showntotransport radiolabelled melibiose, raffinose, isomaltotriose, and isomaltotetraose, andthetransport function was also subjected toinduction byraffinose, an inducer ofthemsm operoninS.mutans.Theresults confirm theroleofthemsm operon inthetransport andmetabolism of melibiose, raffinose, andisomaltosaccharides. Sugar fermentation plays animportant role inmaintaining Streptococcus mutansontooth surfaces, whereitcancause dental caries (11). Investigations overthepastdecade (14) haveshownthatthemajoruptake mechanism formost sugars inS.mutansisthephosphoenolpyruvate-dependent phosphotransferase system(PTS). ThePTSsugars include glucose, mannitol, sorbitol, lactose, sucrose, mannose, fructose,maltose, N-acetylglucosamine, andtrehalose. Al