Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 22875852Publication DOI: 10.1074/jbc.M112.401000DAJournal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: cwhitfie
uoguelph.ca
Institutions: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
The Escherichia coli O9a and O8 O-antigen serotypes represent model systems for the ABC transporter-dependent synthesis of bacterial polysaccharides. The O9a and O8 antigens are linear mannose homopolymers containing conserved reducing termini (the primer-adaptor), a serotype-specific repeat-unit domain, and a terminator. Synthesis of these glycans occurs on the polyisoprenoid lipid-linked primer, undecaprenyl pyrophosphoryl-GlcpNAc, by two conserved mannosyltransferases, WbdC and WbdB, and a serotype-specific mannosyltransferase, WbdA. The glycan structure and pattern of conservation in the O9a and O8 mannosyltransferases are not consistent with the existing model of O9a biosynthesis. Here we establish a revised pathway using a combination of in vivo (mutant complementation) experiments and in vitro strategies with purified enzymes and synthetic acceptors. WbdC and WbdB synthesize the adaptor region, where they transfer one and two α-(1→3)-linked mannose residues, respectively. The WbdA enzymes are solely responsible for forming the repeat-unit domains of these O antigens. WbdA(O9a) has two predicted active sites and polymerizes a tetrasaccharide repeat unit containing two α-(1→3)- and two α-(1→2)-linked mannopyranose residues. In contrast, WbdA(O8) polymerizes trisaccharide repeat units containing single α-(1→3), α-(1→2) and β-(1→2)-mannopyranoses. These studies illustrate assembly systems exploiting several mannosyltransferases with flexible active sites, arranged in single and multi-domain formats
biosynthesis, Escherichia coli, O-antigens, mannosyltransferases
Structure type: polymer chemical repeating unit
Location inside paper: p.35083 fig.1A
Trivial name: mannose homopolysaccharide
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_115576,IEDB_130701,IEDB_136104,IEDB_140116,IEDB_141111,IEDB_141795,IEDB_141830,IEDB_143632,IEDB_144983,IEDB_152206,IEDB_153756,IEDB_164174,IEDB_164175,IEDB_164176,IEDB_164480,IEDB_174840,IEDB_241100,IEDB_76933,IEDB_983930,SB_136,SB_196,SB_197,SB_44,SB_67,SB_72
Methods: 13C NMR, 1H NMR, NMR-2D, SDS-PAGE, DNA techniques, MALDI-TOF MS, NMR-1D, biochemical methods, computer analysis with CASPER, CE
Synthetic data: enzymatic
Related record ID(s): 27164, 28347, 28349, 28350
NCBI Taxonomy refs (TaxIDs): 1010797Reference(s) to other database(s): GTC:G87424QV, GlycomeDB:
668, CCSD:
47538
Show glycosyltransferases
There is only one chemically distinct structure:
Found 
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