2gn4

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Template:STRUCTURE 2gn4

Crystal structure of UDP-GlcNAc inverting 4,6-dehydratase in complex with NADPH and UDP-GlcNAc

Overview

FlaA1 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.

About this Structure

2GN4 is a Single protein structure of sequence from Helicobacter pylori. Full crystallographic information is available from OCA.

Reference

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 Page seeded by OCA on Sun May 4 05:17:43 2008