Chemical analyses and mass spectrometry were used to study the structure of the lipopolysaccharide (LPS) isolated from Aeromonas bestiarum strain K296, serotype O18. ESI-MS revealed that the most abundant A. bestiarum LPS glycoforms have a hexa-acylated or tetra-acylated lipid A with conserved architecture of the backbone, consisting of a 1,4'-bisphosphorylated β-(1→6)-linked d-GlcN disaccharide with an AraN residue as a non-stoichiometric substituent and a core oligosaccharide composed of Kdo1Hep6Hex1HexN1P1. 1D and 2D NMR spectroscopy revealed that the O-specific polysaccharide (OPS) of A. bestiarum K296 consists of a branched tetrasaccharide repeating unit containing two 6-deoxy-l-talose (6dTalp), one Manp and one GalpNAc residues; thus, it is similar to that of the OPS of A. hydrophila AH-3 (serotype O34) in both the sugar composition and the glycosylation pattern. Moreover, 3-substituted 6dTalp was 2-O-acetylated and additional O-acetyl groups were identified at O-2 and O-4 (or O-3) positions of the terminal 6dTalp. Western blots with polyclonal rabbit sera showed that serotypes O18 and O34 share some epitopes in the LPS. The very weak reaction of the anti-O34 serum with the O-deacylated LPS of A. bestiarum K296 might have been due to the different O-acetylation pattern of the terminal 6dTalp. The latter suggestion was further confirmed by NMR.
Lipopolysaccharide, LPS, O-specific polysaccharide, Aeromonas bestiarum, Fish pathogen, OPS, 6dTal
NCBI PubMed ID: 23595053Publication DOI: 10.3390/md11041235Journal NLM ID: 101213729Publisher: Basel, Switzerland: Molecular Diversity Preservation International
Correspondence: aturska@hektor.umcs.lublin.pl
Institutions: Division of Structural Biochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Airway Research Center North (ARCN), Member of the German Center for Lung Research (DZL), Parkallee 4a/c, D-23845 Borstel, Germany, Division of Immunochemistry, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 10, D-23845 Borstel, Germany, Department of Genetics and Microbiology, Maria Curie-Sklodowska University, Akademicka 19, Lublin 20-033, Poland, Department of Fish Diseases, National Veterinary Research Institute, Partyzantow 57, Pulawy 24-100, Poland
Methods: 13C NMR, 1H NMR, methylation, NMR-2D, GC-MS, de-O-acylation, SDS-PAGE, ESI-ICR-MS, Western blotting, de-O-acetylation, composition analysis, NMR-1D, serological methods
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