Abstract
Many bacterial pathogens express lipooligosaccharides that mimic human cell surface glycoconjugates, enabling them to attach to host receptors and to evade the immune response. In Neisseria meningitidis, the galactosyltransferase LgtC catalyzes a key step in the biosynthesis of lipooligosaccharide structure by transferring alpha-d-galactose from UDP-galactose to a terminal lactose. The product retains the configuration of the donor sugar glycosidic bond; LgtC is thus a retaining glycosyltranferase. We report the 2 A crystal structures of the complex of LgtC with manganese and UDP 2-deoxy-2-fluoro-galactose (a donor sugar analog) in the presence and absence of the acceptor sugar analog 4'-deoxylactose. The structures, together with results from site-directed mutagenesis and kinetic analysis, give valuable insights into the unique catalytic mechanism and, as the first structure of a glycosyltransferase in complex with both the donor and acceptor sugars, provide a starting point for inhibitor design.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins*
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Binding Sites
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Carbohydrate Metabolism*
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Carbohydrates / chemistry
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Catalysis
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Crystallography, X-Ray
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Drug Design
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Galactosyltransferases / antagonists & inhibitors
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Galactosyltransferases / chemistry*
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Galactosyltransferases / genetics
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Galactosyltransferases / metabolism*
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Glycosyltransferases / antagonists & inhibitors
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Glycosyltransferases / chemistry*
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Glycosyltransferases / genetics
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Glycosyltransferases / metabolism*
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Hydrogen Bonding
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Kinetics
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Lactose / analogs & derivatives
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Lactose / metabolism
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Manganese / metabolism
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Models, Molecular
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Molecular Sequence Data
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Mutation / genetics
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Neisseria meningitidis / enzymology*
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Neisseria meningitidis / genetics
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Protein Structure, Secondary
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Sequence Alignment
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Uridine Diphosphate Galactose / analogs & derivatives*
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Uridine Diphosphate Galactose / metabolism
Substances
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Bacterial Proteins
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Carbohydrates
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UDP-2-fluoro-2-deoxygalactose
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Uridine Diphosphate Galactose
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Manganese
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Glycosyltransferases
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LgtC protein, Neisseria
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Galactosyltransferases
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Lactose