Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
The structure was elucidated in this paperNCBI PubMed ID: 8830704Publication DOI: 10.1128/jb.178.20.6043-6048.1996Journal NLM ID: 2985120RPublisher: American Society for Microbiology
Correspondence: azorre
iris.iib.uba.ar
Institutions: Instituto de Investigaciones Bioquímicas, Fundación Campomar, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
Cyclic 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
Structure type: cyclic polymer repeating unit
Location inside paper: p.6045
Trivial name: cyclosophoran, cyclic β-1,2-glucan, cyclic (β 1-2)-D-glucan, cyclic b-(1,2)-glucan
Compound class: EPS, LOS, CPS
Contained glycoepitopes: IEDB_140628,IEDB_142488,IEDB_146664,IEDB_983931,SB_192
Methods: gel filtration, acid hydrolysis, paper chromatography, biochemical methods, HPLC, PAGE, radiolabeled synthesis, digestion with glusulase
Synthetic data: enzymatic
NCBI Taxonomy refs (TaxIDs): 358Reference(s) to other database(s): GTC:G21553SY, GlycomeDB:
25048
Show glycosyltransferases
There is only one chemically distinct structure:
Taxonomic group: algae / Chlorophyta
(Phylum: Chlorophyta)
NCBI PubMed ID: 6692821Journal NLM ID: 0107600Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Institutions: Institute of Biochemistry, Köln
Crude membrane fractions from Volvox carteri in the presence of detergent and metal complexing agent catalyze the transfer of glucose from dolichyl phosphate glucose to branched dolichyl diphosphate chitobiosyl pentamannoside Dol-PP-(GlcNAc)2-(Man)5, a known intermediate of the lipid-mediated pathway of N-glycosylation of proteins, resulting in the formation of Dol-PP-(GlcNAc)2-(Man)5-(Glc)1. Under the various conditions tested, neither Dol-P-Man nor other known mannosyl donors of the nucleoside-activated or lipid-activated type can serve as donor molecules for the elongation of the lipid-linked heptasaccharide. On the other hand, calf liver microsomes in similar experiments mannosylated the heptasaccharide further with Dol-P-Man up to a nonamannoside, Dol-PP-(GlcNAc)2-(Man)9. A direct glucosylation of the acceptor, however, with Dol-P-Glc failed in this system. The (GlcNAc)2-(Man)5-(Glc)1, obtained after mild acid hydrolysis of the above glycolipid is not significantly split by an unspecific α-glucosidase from yeast. However, Volvox microsomes liberated most of the glucose indicating a specific glucosidase in the membranes of the alga. This enzyme does not act on (GlcNAc)2-(Man)9-(Glc)1, the usual protein-linked carbohydrate intermediate of trimming processes of N-glycosidic glycoproteins. The data on glycolipid formation let us postulate that in Volvox the normal N-glycosylation pathway differs from that found in higher plants and animals either by a lack of evolution or by mutation in the genes coding for the mannosyl transferases involved.
Structure type: oligomer
Compound class: N-glycan
Contained glycoepitopes: IEDB_123886,IEDB_130701,IEDB_135813,IEDB_136104,IEDB_137340,IEDB_137485,IEDB_140116,IEDB_141793,IEDB_141807,IEDB_141830,IEDB_143632,IEDB_144983,IEDB_150077,IEDB_151531,IEDB_152206,IEDB_540671,IEDB_548907,IEDB_983930,SB_136,SB_196,SB_197,SB_198,SB_33,SB_44,SB_67,SB_72,SB_73,SB_74,SB_85
Methods: gel filtration, TLC, enzymatic digestion, radiolabeled synthesis, oligosaccharide glucosidase assay
NCBI Taxonomy refs (TaxIDs): 3068Reference(s) to other database(s): CCSD:
5868, CBank-STR:17550
Show glycosyltransferases
There is only one chemically distinct structure:
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