The Structure of the Carbohydrate Backbone of the Lipopolysaccharide from Acinetobacter Strain ATCC 17905

Abstract

The structure of the carbohydrate backbone of the lipopolysaccharide from Acinetobacter strain ATCC 17905 was studied. After deacylation of the lipopolysaccharide, a mixture of two compounds (ratio approximately 2 : 1) was isolated by high-performance anion-exchange chromatography, the structures of which were determined by NMR spectroscopy and electrospray-mass spectrometry as cr-Glc-(l-6)-j-Glc-(l-3)-~-Gal-(1-7)-a-Kdo[Sug, 3-deoxy-~-manno-2-octulopyranosonic acid (Kdo) in oligosaccharjde 1 (major portion) and ~-g / y cero-~-~a/o-2-octulopyranosonic acid (KO) in oligosaccharide 2 (minor portion)]. All monosaccharide residues also possess the D-configuration and are present in the pyranose form.Keyn~ords: Acinetobacter; lipopolysaccharide; NMR; core-lipid A region.Bacteria assigned to the genus Acinetobacter (Moraxelluceue) are gram-negative organisms that occur in Nature in soil and water, but which also have increasingly been identified as the causative agents of nosocomial infections, e.g. respiratory tract infections, bacteremia, and secondary meningitis [I].The outer membrane of Acinetobucter strains contains lipopolysaccharides (LPS) that are useful chemotaxonomic and antigenic markers for their identification and differentiation. Until recently, LPS from Acinetobacter were described to occur only as rough types. However, several reports have now been published in which the identification and analysis of S-form LPS was described [2-61. Of the rough type LPS, mainly those from Acinetobacter strains NCTC 10303 and NCTC 10305 were studied (7-121 and in the LPS from the last strain, a novel octulosonic acid was identified and characterised as D-glycero-D-tak-octulosonic acid (KO) 19, 10, 121. The KO residue replaces that of 3-deoxy-D-munno-octulosonic acid (Kdo) which links the core region to lipid A, leading to a drastic change in linkage stability under acidic hydrolysis conditions : whereas LPS are cleaved easily between Kdo and lipid A, harsh acidic conditions are required to cleave between KO and lipid A.In this study, we report the structural elucidation of the core region of LPS from Acinetobucter strain ATCC 17905. MATERIALS AND METHODSBacteria and bacterial LPS. Acinetobacter strain ATCC 17905 was obtained from the American Type Culture Collection. The bacteria were cultivated in a fermenter (10 l), and the cells were killed with phenol and centrifuged at 5000 g for 20 min. The LPS was isolated by extraction of the bacteria with phenol/ chlorofordlight petroleum [13] in a yield of 2.5% dry bacterial mass.Analytical methods. SDS/PAGE and staining of the gel with silver nitrate were performed as reported in [2]. The determination of the absolute configurations of glucose, galactose, galacturonic acid, and glucosamine, methylation and monosaccharide analyses were as described [141. NMR spectroscopy. 'H-NMR and "C-NMR spectra were recorded in D,O at 300 K on a Bruker AMX-600 spectrometer using standard Bruker software. The chemical shifts are given relative to internal acetone (6 2.225 ppm) for 'H-and to ...

Phosphoethanolamine Modification of Lipid A in Colistin-Resistant Variants of Acinetobacter baumannii Mediated by the pmrAB Two-Component Regulatory System

“…Previous studies have unambiguously shown that the lipid A disaccharide backbone of Acinetobacter spp. is composed of two ␤-(1-6)-linked 2-amino-2-deoxyglucose residues (GlcNI and GlcNII) phosphorylated at positions 1 and 4Ј (22,23,49). The lipid A fraction of A. baumannii contains two major species which may correspond to a hepta-acylated lipid A with two 2-amino-2-deoxyglucose residues, two phosphates, (22) (Fig.…”

Dioxygenases in Burkholderia ambifaria and Yersinia pestis that hydroxylate the outer Kdo unit of lipopolysaccharide

“…Two Kdo residues are usually present, one of which is linked directly to lipid A. A subset of Gramnegative bacteria, including B. cepacia (10-12), Y. pestis (13,14), and some strains of Acinetobacter (26,27), contain an unusual analog of Kdo, known as Ko, in which the axial hydrogen atom at position 3 of Kdo is replaced with an OH group (Fig. 1A).…”

A New Type of Glycosidic Linkage: An Open-Chain Acetal-LinkedN-Acetylgalactosamine in the Core Part of the Lipopolysaccharides fromProteus Microorganisms

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