EC Explorer

4.2.1.115

UDP-N-acetylglucosamine 4,6-dehydratase (configuration-inverting)

UDP-N-acetyl-α-D-glucosamine = UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose + H₂O

FlaA1, UDP-N-acetylglucosamine 5-inverting 4,6-dehydratase, PseB, UDP-N-acetylglucosamine hydro-lyase (inverting, UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose-forming)

UDP-N-acetyl-α-D-glucosamine hydro-lyase (inverting; UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose-forming)

Contains NADP⁺ as a cofactor. This is the first enzyme in the biosynthetic pathway of pseudaminic acid [3], a sialic-acid-like sugar that is unique to bacteria and is used by Helicobacter pylori to modify its flagellin. This enzyme plays a critical role in H. pylori’s pathogenesis, being involved in the synthesis of both functional flagella and lipopolysaccharides [1,2]. It is completely inhibited by UDP-α-D-galactose. The reaction results in the chirality of the C-5 atom being inverted. It is thought that Lys-133 acts sequentially as a catalytic acid, protonating the C-6 hydroxy group and as a catalytic base, abstracting the C-5 proton, resulting in the elimination of water. This enzyme belongs to the short-chain dehydrogenase/reductase family of enzymes.

created 2009