Structural highlights
Function[KDTA_AQUAE] Involved in lipopolysaccharide (LPS) biosynthesis. Catalyzes the transfer of a single 3-deoxy-D-manno-octulosonate (Kdo) residue from CMP-Kdo to lipid IV(A), the tetraacyldisaccharide-1,4'-bisphosphate precursor of lipid A. Is strictly monofunctional, i.e. is capable of adding only a single Kdo residue to the acceptor lipid.[1] Publication Abstract from PubMedWaaA is a key enzyme in the biosynthesis of LPS, a critical component of the outer envelope of Gram-negative bacteria. Embedded in the cytoplasmic face of the inner membrane, WaaA catalyzes the transfer of 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) to the lipid A precursor of LPS. Here we present crystal structures of the free and CMP-bound forms of WaaA from Aquifex aeolicus, an ancient Gram-negative hyperthermophile. These structures reveal details of the CMP-binding site and implicate a unique sequence motif (GGS/TX(5)GXNXLE) in Kdo binding. In addition, a cluster of highly conserved amino acid residues was identified which represents the potential membrane-attachment and acceptor-substrate binding site of WaaA. A series of site-directed mutagenesis experiments revealed critical roles for glycine 30 and glutamate 31 in Kdo transfer. Our results provide the structural basis of a critical reaction in LPS biosynthesis and allowed the development of a detailed model of the catalytic mechanism of WaaA. Structural and mechanistic analysis of the membrane-embedded glycosyltransferase WaaA required for lipopolysaccharide synthesis.,Schmidt H, Hansen G, Singh S, Hanuszkiewicz A, Lindner B, Fukase K, Woodard RW, Holst O, Hilgenfeld R, Mamat U, Mesters JR Proc Natl Acad Sci U S A. 2012 Apr 2. PMID:22474366[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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