3-deoxy-2-octulosonic-acid(2)-lipid-iv(a) and lauric-acid

Unlike Escherichia coli, living cells of Pseudomonas aeruginosa can complete the fatty acylation of lipid A when the biosynthesis of 3-deoxy-D-manno-octulosonate (Kdo) is inhibited (R. C. Goldman, C. C. Doran, S. K. Kadam, and J. O. Capobianco, J. Biol. Chem. 263:5217-5233, 1988). In this study, we demonstrate the presence of a novel enzyme in extracts of P. aeruginosa that can transfer lauroyl-acyl carrier protein (ACP) to a tetraacyl disaccharide-1,4'-bis-phosphate precursor of lipid A (termed lipid IVA) that accumulates in Kdo-deficient mutants of E. coli. Comparable E. coli extracts cannot transfer laurate from lauroyl-ACP to lipid IVA, only to (Kdo)2-lipid IVA (K. A. Brozek, and C. R. H. Raetz, J. Biol. Chem. 265:15410-15417, 1990). P. aeruginosa extracts do not utilize myristoyl- or R-3-hydroxymyristoyl-ACP instead of lauroyl-ACP to acylate lipid IVA. Laurate incorporation in P. aeruginosa extracts is dependent upon time, protein concentration, and the presence of Triton X-100 but is inhibited by lauroyl-coenzyme A. P. aeruginosa extracts transfer only one laurate to lipid IVA, whereas E. coli extracts can transfer two laurates to (Kdo)2-lipid IVA. These results demonstrate that incorporation of laurate into lipid A does not require prior attachment of Kdo in all gram-negative bacteria.

Topics: Acyl Carrier Protein; Acylation; ADP Ribose Transferases; Bacterial Toxins; Cell-Free System; Cytoplasm; Exotoxins; Glycolipids; Glycoproteins; Lauric Acids; Lipid A; Pseudomonas aeruginosa; Pseudomonas aeruginosa Exotoxin A; Spectrometry, Mass, Fast Atom Bombardment; Substrate Specificity; Sugar Acids; Transferases; Virulence Factors