UDP-3-O-acyl-glucosamine N-acyltransferase (LpxD): The enzyme catalyzes the transfer of 3-hydroxymyristic acid or 3-hydroxy-arachidic acid, depending on the organism, from the acyl carrier protein (ACP) to UDP-3-O-acyl-glucosamine to produce UDP-2,3-diacyl-GlcNAc. This constitutes the third step in the lipid A biosynthetic pathway in Gram-negative bacteria. LpxD is a homotrimer, with each subunit consisting of a novel combination of an N-terminal uridine-binding domain, a core lipid-binding left-handed parallel beta helix (LbH) domain, and a C-terminal alpha-helical extension. The LbH domain contains 9 turns, each containing three imperfect tandem repeats of a hexapeptide repeat motif (X-[STAV]-X-[LIV]-[GAED]-X).
Comment:Active LpxD is trimeric, with active sites located at the interface between two LbH subunits. The trimer structure contains three active sites and each subunit contributes to two active sites via residues located on two surfaces.
Structure:2IU8_A; Chlamydia trachomatis LpxD binds UDP-GlcNAc and palmitic acid; defined at 3.5A contacts. - View structure with Cn3D