Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: gastroenteritis [ICD11:
1A40.0 
];
infection due to Campylobacter jejuni [ICD11:
XN4Q5 ]
NCBI PubMed ID: 19887444Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: tlowary
ualberta.a
Institutions: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
UDP-galactopyranose mutases (UGM) are the enzymes responsible for the synthesis of UDP-galactofuranose (UDP-Galf) from UDP-galactopyranose (UDP-Galp). The enzyme, encoded by the glf gene, is present in bacteria, parasites, and fungi that express Galf in their glycoconjugates. Recently, a UGM homologue encoded by the cj1439 gene has been identified in Campylobacter jejuni 11168, an organism possessing no Galf-containing glycoconjugates. However, the capsular polysaccharide from this strain contains a 2-acetamido-2-deoxy-d-galactofuranose (GalfNAc) moiety. Using an in vitro high performance liquid chromatography assay and complementation studies, we characterized the activity of this UGM homologue. The enzyme, which we have renamed UDP-N-acetylgalactopyranose mutase (UNGM), has relaxed specificity and can use either UDP-Gal or UDP-GalNAc as a substrate. Complementation studies of mutase knock-outs in C. jejuni 11168 and Escherichia coli W3110, the latter containing Galf residues in its lipopolysaccharide, demonstrated that the enzyme recognizes both UDP-Gal and UDP-GalNAc in vivo. A homology model of UNGM and site-directed mutagenesis led to the identification of two active site amino acid residues involved in the recognition of the UDP-GalNAc substrate. The specificity of UNGM was characterized using a two-substrate co-incubation assay, which demonstrated, surprisingly, that UDP-Gal is a better substrate than UDP-GalNAc.
gene, Escherichia coli, recognition, capsular polysaccharide, Campylobacter jejuni, mutase
Structure type: polymer chemical repeating unit
Location inside paper: p.494, fig.2
Compound class: CPS
Contained glycoepitopes: IEDB_115136,IEDB_137473,IEDB_140630,IEDB_149136
Methods: 1H NMR, PCR, genetic methods, biochemical methods, cloning
Enzymes that release or process the structure: UDP-N-acetylgalactopyranose mutase (UNGM)
Biosynthesis and genetic data: genetic data, biochemical data
Synthetic data: enzymatic
Comments, role: Campylobacter jejuni 11168 (HS:2 serotype)
NCBI Taxonomy refs (TaxIDs): 197
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There is only one chemically distinct structure:
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