Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 9006904Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Institutions: Department of Medical and Physiological Chemistry, University of Uppsala, The Biomedical Center, S-751 23 Uppsala, Sweden
Escherichia coli K4 bacteria synthesize a capsule polysaccharide (GalNAc-GlcA(fructose))n with the carbohydrate backbone identical to chondroitin. GlcA- and GalNAc-transferase activities from the bacterial membrane were assayed with acceptors derived from the capsule polysaccharide and radiolabeled UDP-[14C]GlcA and UDP-[3H]GalNAc, respectively. It was shown that defructosylated oligosaccharides (chondroitin) could serve as substrates for both the GlcA- and the GalNAc-transferases. The radiolabeled products were completely degraded with chondroitinase AC; the [14C]GlcA unit could be removed by β-D-glucuronidase, and the [3H]GalNAc could be removed by β-N-acetylhexosaminidase. A fructosylated oligosaccharide acceptor tested for GlcA-transferase activity was found to be inactive. These results indicate that the chain elongation reaction of the K4 polysaccharide proceeds in the same way as the polymerization of the chondroitin chain, by the addition of the monosaccharide units one by one to the nonreducing end of the polymer. This makes the biosynthesis of the K4 polysaccharide an interesting parallel system for studies of chondroitin sulfate biosynthesis. In the biosynthesis of capsule polysaccharides from E. coli, a similar mechanism has earlier been demonstrated for polysialyl (NeuNAc)n (Rohr, T. E., and Troy, F. A. (1980) J. Biol. Chem. 255, 2332-2342) and for the K5 polysaccharide (GlcAβ1-4GlcNAcα1-4)n (Lidholt, K., Fjelstad, M., Jann, K., and Lindahl, U. (1994) Carbohydr. Res. 255, 87-101). In contrast, chain elongation of hyaluronan (GlcAβ1-3GlcNAcβ1-4)n is claimed to occur at the reducing end (Prehm, P. (1983) Biochem. J. 211, 181-189).
biosynthesis, Escherichia coli, glycosyltransferases, capsule, chondroitin, capsule polysaccharide
Structure type: polymer chemical repeating unit
Location inside paper: p.2683, fig. 1, B
Compound class: CPS, K-antigen
Contained glycoepitopes: IEDB_115136,IEDB_130648,IEDB_137473,IEDB_140630,IEDB_153510,IEDB_423153
Biosynthesis and genetic data: biosynthesis data
Comments, role: published polymerization frame was shifted for conformity with other records.
Related record ID(s): 7508
NCBI Taxonomy refs (TaxIDs): 562Reference(s) to other database(s): GTC:G09906MP, GlycomeDB:
16774
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There is only one chemically distinct structure:
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