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Found 1 structure.
Displayed structure 1
| Cyclic -2)-b-D-Glcp-(1- | Show graphically |
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Structure type: cyclic polymer repeating unit
Trivial name: cyclosophoran, cyclic β-1,2-glucan, cyclic (β 1-2)-D-glucan, cyclic b-(1,2)-glucan
Compound class: CPS, EPS, LOS
Contained glycoepitopes: IEDB_140628,IEDB_142488,IEDB_146664,IEDB_983931,SB_192
Brucella native haptens (NHs) extracted with hot water from smooth (S)-type B. abortus and B. melitensis were purified to high levels of serological activity and compared with the polysaccharide obtained by acid hydrolysis (PS) of the S lipopolysaccharide (S-LPS). By 13C nuclear magnetic resonance analysis, NHs showed the spectrum of a homopolymer of a-1,2- or a-1,2- plus a-1,3-linked 4-formamido-4,6-dideoxy-D-mannose (N-formylperosamine) previously reported for the LPS O chain. However, while PS contained up to 0.6% 3-deoxy-D-manno-2-octulosonate, this LPS-core marker was absent from NH. High performance liquid chromatography and thin-layer chromatography showed heterogeneity in NH purified from whole cells but not in PS. By immunoprecipitation, polysaccharides indistinguishable from NH were demonstrated in extracts obtained with phenol-water, saline at 60 C, and ether-water treatments, and none of these treatments caused S-LPS hydrolysis detectable with antibodies to the O chain and lipid A. Two lines of evidence showed that NH was in the cell surface. First, NH became biotinylated when B. abortus live cells were labelled with biotin-hydrazide, and the examination of cell fractions and electron microscopy sections with streptavidin-peroxidase and streptavidin-coloidal gold, respectively, showed that labelling was extrinsic. Moreover, whereas only traces of NH were found in cytosols, the amount of NH was enriched in cell envelopes and in the outer membrane blebs spontaneously released by brucellae during growth. Interactions between NH and S-LPS were observed in crude cell extracts, and such interactions could be reconstituted by using purified NH and LPS. The results demonstrate that NH is not a hydrolytic product of S-LPS and suggest a model in which LPS-independent O-type polysaccharides (NH) are intertwined with the O chain in the outer membrane of S-type brucellae.
Lipopolysaccharide, LPS, characterization, polysaccharide, polysaccharides, Brucella, Brucella abortus, hapten, Brucella melitensis, membrane, outer membrane, native, Haptens, O-type, smooth
NCBI PubMed ID: 8576040Rhizobium fredii USDA205 cells were cultured in the presence of 4',5,7-trihydroxyflavone (apigenin), a compound that has been shown to induce the nod genes and other symbiosis-related genes in R. fredii. The cell-associated polysaccharides were then extracted with hot phenol/water, separated by repetitive gel filtration chromatography, and analyzed by polyacrylamide gel electrophoresis, nuclear magnetic resonance spectrometry, high-performance anion-exchange chromatography, and gas chromatography. These analyses showed that apigenin effects a modulation in the production of some cell-associated bacterial polysaccharides: 1) The production of a glucan is severely attenuated; 2) the lipopolysaccharide O antigen is modified in composition and M(r) distribution; and 3) the ratio of two extracted polysaccharides, which are structurally analogous to group II K antigens (capsular polysaccharides), is altered. Similar effects resulted from the inclusion of host plant root extract in the growth medium.
NCBI PubMed ID: 8012042In a previous study (Miller, K.J., Kennedy, E.P. and Reinhold, V.N. (1986) Science 231, 48-51) it was reported that the biosynthesis of periplasmic cyclic β-1,2-glucans by Agrobacterium tumefaciens is strictly osmoregulated in a pattern closely similar to that found for the membrane-derived oligosaccharides of Escherichia coli (Kennedy, E.P. (1982) Proc. Natl. Acad. Sci. USA 79, 1092-1095). In addition to the well-characterized neutral cyclic glucan, the periplasmic glucans were found to contain an anionic component not previously reported. Biosynthesis of the anionic component is osmotically regulated in a manner indistinguishable from that of the neutral cyclic β-1,2-glucan. We now find that the anionic component consists of cyclic β-1,2-glucans substituted with one or more sn-1-phosphoglycerol residues. The presence of sn-1-phosphoglycerol residues represents an additional, striking similarity to the membrane-derived oligosaccharides of E. coli.
NCBI PubMed ID: 3297148A family of cyclic b-l,2-glucans, substituted with sn-glycerol-l-phosphate at the C6 position of some of the glucose residues, has been found in the culture supernatant of the fast-growing, broad host range Rhizobium species, NGR234. The dynamic behaviour of the molecules, studied by 13C nuclear magnetic resonance spectroscopy, showed that they are disc-shaped with significant, but limited internal motion.
NMR, polysaccharide, cyclic glucan, 13C-, (Rhizobium)
Publication DOI: 10.1016/0005-2736(87)90263-XPolysaccharide B was extracted from Brucella melitensis 16M and from a rough strain of Brucella abortus 45/20 by autoclaving or trichloroacetic acid extraction of whole cells and by a new method involving mild leaching of cells. The material obtained by either of the established procedures was contaminated by O polysaccharide. The new leaching protocol eliminated this impurity and provided a pure glucan, which was regarded as polysaccharide B. This polysaccharide was found by high-performance liquid chromatography separations, chemical composition, methylation, and two-dimensional homo- and heteronuclear magnetic resonance experiments to be a family of nonreducing cyclic 1,2-linked polymers of β-D-glucopyranosyl residues. The degree of polymerization varied between 17 and 24. Polysaccharide B was essentially identical to cyclic D-glucans produced by Rhizobia, Agrobacteria, and other bacterial species. Pure polysaccharide B did not precipitate with Brucella anti-A or anti-M serum and did not inhibit the serological reaction of Brucella A or M antigen with either bovine or murine monoclonal Brucella anti-A or anti-M serum. Previously described serological reactions of polysaccharide B preparations with Brucella anti-A and anti-M sera are related in this study to the presence in crude extracts of contaminants with the antigenic properties of Brucella lipopolysaccharide O polysaccharidesPolysaccharide B was extracted from Brucella melitensis 16M and from a rough strain of Brucella abortus 45/20 by autoclaving or trichloroacetic acid extraction of whole cells and by a new method involving mild leaching of cells. The material obtained by either of the established procedures was contaminated by O polysaccharide. The new leaching protocol eliminated this impurity and provided a pure glucan, which was regarded as polysaccharide B. This polysaccharide was found by high-performance liquid chromatography separations, chemical composition, methylation, and two-dimensional homo- and heteronuclear magnetic resonance experiments to be a family of nonreducing cyclic 1,2-linked polymers of β-D-glucopyranosyl residues. The degree of polymerization varied between 17 and 24. Polysaccharide B was essentially identical to cyclic D-glucans produced by Rhizobia, Agrobacteria, and other bacterial species. Pure polysaccharide B did not precipitate with Brucella anti-A or anti-M serum and did not inhibit the serological reaction of Brucella A or M antigen with either bovine or murine monoclonal Brucella anti-A or anti-M serum. Previously described serological reactions of polysaccharide B preparations with Brucella anti-A and anti-M sera are related in this study to the presence in crude extracts of contaminants with the antigenic properties of Brucella lipopolysaccharide O polysaccharides
NCBI PubMed ID: 3356461The synthesis of periplasmic cyclic β-1,2-glucans is a property unique to species of the family Rhizobiaceae. For this reason, it is generally believed that these molecules may play an important role in the plant infection process. In the present study, we determined that the cyclic β-1,2-glucans produced by Rhizobium meliloti 1021 were predominantly anionic in character and contained both phosphoglycerol and succinic acid substituents. In addition, we demonstrated that phosphatidylglycerol was the source of the phosphoglycerol substituents present on these oligosaccharides and that greater than 60% of the total phospholipid turnover in this organism involved this substitution reaction.
NCBI PubMed ID: 3170478The ndvA and ndvB genes of Rhizobium meliloti are involved in the export and synthesis, respectively, of the small cyclic polysaccharide β(1,2)glucan. We have previously shown that spontaneous symbiotic pseudorevertants of ndv mutants do not produce periplasmic β(1,2)glucan. Here we show that the pseudorevertants also do not produce extracellular β(1,2)glucan, but do show alterations in the amount of the major acidic exopolysaccharide produced. This exopolysaccharide is not detectably different from that produced by the wild type or by the ndv mutants. A cosmid which suppresses the symbiotic defect of both ndvA and ndvB mutants was isolated from a gene bank prepared from DNA of an ndvA pseudorevertant. This cosmid contains a number of exo genes, including exoH and exoF. Subcloning and Tn5 mutagenesis were used to show that the widely separated exoH and exoF genes are both involved in suppression of the ndv mutant phenotype and that the 3.5 kb DNA fragment which contains the exoH gene does not carry the mutation responsible for second site suppression.
NCBI PubMed ID: 1560776A gene (ndvB) in Rhizobium meliloti that is essential for nodule development in Medicago sativa (alfalfa), specifies synthesis of a large membrane protein. This protein appears to be an intermediate in β-1,2-glucan synthesis by the microsymbiont. Southern hybridization analysis showed strong homology between an ndvB (chvB) probe and genomic DNA of R. fredii but not from Bradyrhizobium japonicum. A cosmid clone containing the putative ndvB locus was isolated from a Rhizobium fredii gene library. The cosmid clone which complemented R. meliloti ndvB mutants for synthesis of β-1,2-glucans and effective nodulation of alfalfa was mapped and subcloned. Fragment-specific Tn5 mutagenesis followed by homologous recombination into the R. fredii genome indicated that the region was essential for β-1,2-glucan synthesis and for formation of an effective symbiosis with Glycine max (soybean).
NCBI PubMed ID: 1406255Cyclic β-1,2-glucans (CβG) are osmolyte homopolysaccharides with a cyclic β-1,2-backbone of 17-25 glucose residues present in the periplasmic space of several bacteria. Initiation, elongation, and cyclization, the three distinctive reactions required for building the cyclic structure, are catalyzed by the same protein, the CβG synthase. The initiation activity catalyzes the transference of the first glucose from UDP-glucose to a yet-unidentified amino acid residue in the same protein. Elongation proceeds by the successive addition of glucose residues from UDP-glucose to the nonreducing end of the protein-linked β-1,2-oligosaccharide intermediate. Finally, the protein-linked intermediate is cyclized, and the cyclic glucan is released from the protein. These reactions do not explain, however, the mechanism by which the number of glucose residues in the cyclic structure is controlled. We now report that control of the degree of polymerization (DP) is carried out by a β-1,2-glucan phosphorylase present at the CβG synthase C-terminal domain. This last activity catalyzes the phosphorolysis of the β-1,2-glucosidic bond at the nonreducing end of the linear protein-linked intermediate, releasing glucose 1-phosphate. The DP is thus regulated by this 'length-controlling' phosphorylase activity. To our knowledge, this is the first description of a control of the DP of homopolysaccharides
glycosyltransferases, mechanism, Bacillus, beta-Glucanscyclic, degree of polymerization, cyclic β-1, 2-glucan, size control
NCBI PubMed ID: 17921247Alcaligenes faecalis var. myxogenes 10C3, which we isolated from soil, produces a water-soluble and an insoluble extracellular polysaccharide. The former (succinoglycan) is composed of glucose, galactose, pyruvic acid and succinic acid (molar proportions 7:1:1:1) with (β 1-3)-, (β 1-4)- and (β 1-6)-glucosidic linkages. The latter (curdlan) is composed entirely of (β 1-3)-linked D-glucose and forms a resilient firm gel when heated in suspension. The organism also produces extracellularly a repeating-unit octasaccharide of succinoglycan and cyclic (β 1-2)-D-glucan. These polymers or oligomers are also produced by many strains of Agrobacterium and Rhizobium. Spontaneous mutation in ability to produce these polysaccharides or oligosaccharides occurs in these strains. The structures of succinoglycan, and similar polymers containing riburonic acid or galactose as the end residue of the side chain, were elucidated by successive fragmentation with two special enzymes obtained from Cytophaga arvensicola followed by methylation analysis. It is interesting that the unit compound in the biosynthesis of succinoglycan is identical with the unit compound in the enzymic decomposition of the polymer. Studies on curdlan gel by X-ray, 13C n.m.r. and electron-microscopic analysis and other physicochemical methods showed that the molecular structure of curdlan changes from a single helix to a triple stranded helix on heat treatment at high temperature. Curdlan seems to be useful for making new types of jelly products and may also be useful in new procedures for food production. Interestingly, curdlan possesses marked antitumour activity. Extracellular isoamylase (EC 3.2.1.68; glycogen 6-glucanohydrolase) of Pseudomonas amyloderamosa SB 15, which we isolated from soil, is very useful for elucidation of the structure of amylopectin and glycogen, and also for the commercial production of amylose or maltose alone or in combination with beta-amylase. Maltose is useful as a sugar for injection, being better than glucose. Maltitol is easily produced from maltose by chemical reduction and is used as a low-calorie sweetener. The isoamylase is also effective for enhancing the production of glucose from starch by the action of glucoamylase.
bacterial polysaccharides, β-Glucans, Alcaligenes faecalis
NCBI PubMed ID: 6400487Cyclic β-(1,2)-glucans are synthesized by members of the Rhizobiaceae family through protein-linked oligosaccharides as intermediates. The protein moiety is a large inner membrane molecule of about 319 kDa. In Agrobacterium tumefaciens and in Rhizobium meliloti the protein is termed ChvB and NdvB, respectively. Inner membranes of R. meliloti 102F34 and A. tumefaciens A348 were first incubated with UDP-[14C]Glc and then solubilized with Triton X-100 and analyzed by polyacrylamide gel electrophoresis under native conditions. A radioactive band corresponding to the 319-kDa protein was detected in both bacteria. Triton-solubilized inner membranes of A. tumefaciens were submitted to native electrophoresis and then assayed for oligosaccharide-protein intermediate formation in situ by incubating the gel with UDP-[14C]Glc. A [14C]glucose-labeled protein with an electrophoretic mobility identical to that corresponding to the 319-kDa [14C]glucan protein intermediate was detected. In addition, protein-linked radioactivity was partially chased when the gel was incubated with unlabeled UDP-Glc. A heterogeneous family of cyclic β-(1,2)-glucans was formed upon incubation of the gel portion containing the 319-kDa protein intermediate with UDP-[14C]Glc. A protein with an electrophoretic behavior similar to the 319-kDa protein intermediate was 'in gel' labeled by using Triton-solubilized inner membranes of an A. tumefaciens exoC mutant, which contains a protein intermediate without nascent glucan. These results indicate that initiation (protein glucosylation), elongation, and cyclization were catalyzed in situ. Therefore, the three enzymatic activities detected in situ reside in a unique protein component (i.e., cyclic β-(1,2)-glucan synthase). It is suggested that the protein component is the 319-kDa protein intermediate, which might catalyze the overall cyclic β-(1,2)-glucan synthesis.
biosynthesis, synthesis, cyclic, Rhizobium meliloti, Rhizobiaceae, β-Glucans, inner membrane
NCBI PubMed ID: 8830704| New query | Export IDs | Home | Help |
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