title: Structural and biological characterisation of a novel tetra-acyl lipid A from Escherichia coli F515 lipopolysaccharide acting as endotoxin antagonist in human monocytes.
abstract: We here report on the structural analysis of a novel tetra-acyl lipid A (LA (tetra) ) isolated from Escherichia coli deep rough (Re)-mutant strain F515. In addition to the biologically active hexa-acyl E. coli-type lipid A (compound 506), this incompletely acylated lipid A was found to be also present in the native LPS. Its structure was studied without further derivatisation by chemical analysis, matrix-assisted laser desorption/ionization mass spectrometry, and one- and two-dimensional (1)H- and (13)C-NMR spectroscopy. It was found to be structurally distinct from the tetra-acyl lipid A biosynthetic precursor Ia (compound 406) in lacking the primary (R)-3-hydroxytetradecanoic acid 14:0(3-OH) in position 3' ester-linked to the 'non-reducing' glucosamine (GlcN II). The hydroxyl group at the (R)-3-hydroxytetradecanoic acid attached to position 2' of GlcN II was found to be substituted by dodecanoic acid (12:0), thus forming a dodecanoyloxytetradecanoyl residue 14:0[3-O(12:0)]. The acylation pattern at the 'reducing' GlcN I was identical to that of compound 406 in having two primary (R)-3-hydroxy tetradecanoic acid residues [14:0(3-OH)] attached to positions 3 (ester-linked) and 2 (amide-linked), respectively. In human mononuclear cells (hMNC) the new LA (tetra) antagonized LPS-induced release of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF) in a dose-dependent manner with identical antagonistic potency as compared with compound 406. Also like compound 406, it was found to be an agonist in murine macrophage-like J774.1 cells.
authors.affiliation: Research Center Borstel, Center for Medicine and Biosciences, Borstel, Germany. uzaehr@fz-borstel.de
authors.forename: U
authors.initials: U
authors.lastname: Zähringer
authors.forename: R
authors.initials: R
authors.lastname: Salvetzki
authors.forename: F
authors.initials: F
authors.lastname: Wagner
authors.forename: B
authors.initials: B
authors.lastname: Lindner
authors.forename: A J
authors.initials: AJ
authors.lastname: Ulmer
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D004306:Dose-Response Relationship, Immunologic; D004731:Endotoxins / Q000037:antagonists & inhibitors*; D004926:Escherichia coli / Q000737:chemistry*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008050:Lipid A / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification / Q000633:toxicity*; D008213:Lymphocyte Activation; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D015394:Molecular Structure; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D004731:Endotoxins; D015850:Interleukin-6; D008050:Lipid A; D014409:Tumor Necrosis Factor-alpha