Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 18536883Journal NLM ID: 8603310Publisher: Kluwer Academic Publishers
Correspondence: brockhau
queensu.ca
Institutions: Department of Biochemistry, Department of Medicine, Division of Rheumatology, and The Arthritis Centre and Human Mobility Research Centre, Queen's University, Etherington Hall, Kingston, ON, K7L 3N6, Canada
Most of the glycosyltransferases involved in O antigen biosynthesis have not yet been characterized. We recently demonstrated that the wbbD gene of the O7 lipopolysaccharide biosynthesis cluster in E. coli strain VW187 (O7:K1) encodes WbbD, a UDP-Gal: GlcNAcα-pyrophosphate-lipid β1,3-Gal-transferase (EC 2.4.1., accession number AAC27537) that transfers the second sugar moiety in the assembly of the O7 repeating unit. The enzyme utilizes undecaprenol-pyrophosphate-GlcNAc as a natural acceptor substrate, but can also transfer Gal to GlcNAcα-PO(3)-PO(3)-(CH(2))(11)-O-phenyl (GlcNAc-PP-PhU). A number of acceptor substrate analogs have now been tested to further characterize the acceptor specificity of WbbD and to determine the roles of the pyrophosphate bond and the lipid moiety in the acceptor substrate. The enzyme was found to have a low activity with a substrate containing only one phosphate group directly α-linked to GlcNAc, and the enzyme was inactive when the phosphate was absent or further removed from the anomeric carbon of GlcNAc. Modifications of the lipid chain yielded substrates with variable activities. GlcNAc derivatives that were inactive as substrates did not inhibit WbbD suggesting that these compounds did not bind to the active site of the enzyme. The specificity of mammalian β4-galactosyltransferase I has been compared to that of WbbD. The results indicate that the bacterial WbbD enzyme has a distinct specificity for GlcNAc-PP-lipid, and that WbbD recognition of its acceptor substrate is very different from that of the ubiquitous mammalian β4-galactosyltransferase I. These studies help to understand mechanisms of O antigen synthesis, to develop methods to synthesize defined oligosaccharide structures and to develop specific O antigen inhibitors.
O-antigen, Escherichia coli, Substrate Specificity, galactosyltransferase, E. coli, O antigen synthesis, undecaprenol-pyrophosphate, enzyme assay
Structure type: suggested polymer biological repeating unit
Location inside paper: p.664
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_130701,IEDB_136044,IEDB_136105,IEDB_137340,IEDB_137472,IEDB_141794,IEDB_141807,IEDB_142078,IEDB_144983,IEDB_150899,IEDB_151531,IEDB_152206,IEDB_190606,IEDB_225177,IEDB_885823,IEDB_983930,SB_137,SB_165,SB_166,SB_187,SB_195,SB_29,SB_44,SB_67,SB_7,SB_72,SB_88
Methods: 13C NMR, 1H NMR, ESI-MS, genetic methods, biosynthetic methods
Biosynthesis and genetic data: genetic data
Synthetic data: enzymatic
Related record ID(s): 22618
NCBI Taxonomy refs (TaxIDs): 2162916Reference(s) to other database(s): GTC:G59988LR, GlycomeDB:
36913
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There is only one chemically distinct structure:
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