2gn4
Crystal structure of UDP-GlcNAc inverting 4,6-dehydratase in complex with NADPH and UDP-GlcNAc
Structural highlights
FunctionPSEB_HELPY Catalyzes the first step in the biosynthesis of pseudaminic acid, a sialic-acid-like sugar that is used to modify flagellin. Has both C6 dehydratase and C5 epimerase activities that result in the production of both UDP-2-acetamido-2,6-dideoxy-beta-L-arabino-4-hexulose and UDP-2-acetamido-2,6-dideoxy-alpha-D-xylo-4-hexulose.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFlaA1 from the human pathogen Helicobacter pylori is an enzyme involved in saccharide biosynthesis that has been shown to be essential for pathogenicity. Here we present five crystal structures of FlaA1 in the presence of substrate, inhibitors, and bound cofactor, with resolutions ranging from 2.8 to 1.9 A. These structures reveal that the enzyme is a novel member of the short-chain dehydrogenase/reductase superfamily. Additional electron microscopy studies show the enzyme to possess a hexameric doughnut-shaped quaternary structure. NMR analyses of "real time" enzyme-substrate reactions indicate that FlaA1 is a UDP-GlcNAc-inverting 4,6-dehydratase, suggesting that the enzyme catalyzes the first step in the biosynthetic pathway of a pseudaminic acid derivative, which is implicated in protein glycosylation. Guided by evidence from site-directed mutagenesis and computational simulations, a three-step reaction mechanism is proposed that involves Lys-133 functioning as both a catalytic acid and base. Structural studies of FlaA1 from Helicobacter pylori reveal the mechanism for inverting 4,6-dehydratase activity.,Ishiyama N, Creuzenet C, Miller WL, Demendi M, Anderson EM, Harauz G, Lam JS, Berghuis AM J Biol Chem. 2006 Aug 25;281(34):24489-95. Epub 2006 May 1. PMID:16651261[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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