title: Structural analysis of lipopolysaccharides from Haemophilus influenzae serotype f. Structural diversity observed in three strains.
abstract: Structural elucidation of the lipopolysaccharide (LPS) from three serotype f Haemophilus influenzae clinical isolates RM6255, RM7290 and RM6252 has been achieved using NMR spectroscopy techniques and ESI-MS on O-deacylated LPS and core oligosaccharide material (OS) as well as ESI-MSn on permethylated dephosphorylated OS. This is the first study to report structural details on LPS from serotype f strains. We found that the LPSs of all strains were highly heterogeneous mixtures of glycoforms expressing the common H. influenzae structural element l-alpha-d-Hepp-(1-->2)-[PEtn-->6]-l-alpha-d-Hepp-(1-->3)-[beta-d-Glcp-(1-->4)]-l-alpha-d-Hepp-(1-->5)-[PPEtn-->4]-alpha-Kdo-(2-->6)-lipid A with variable length of OS chains linked to each of the heptoses. The terminal heptose (HepIII) in RM6255 is substituted at the O-3 position by a beta-d-Glcp residue whereas HepIII in strains RM7290 and RM6252 is substituted at O-2 by the globoside unit (alpha-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-beta-d-Glc) or truncated versions thereof. The central heptose (HepII) is substituted by an alpha-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-beta-d-Glcp-(1-->4)-alpha-d-Glcp unit in RM7290 and RM6252 or truncated versions thereof. Strain RM6255 does not express galactose in its LPS and only shows a cellobiose unit elongating from HepII (beta-d-Glcp-(1-->4)-alpha-d-Glcp). ESI-MSn on dephosphorylated and permethylated OS provided information on the existence of additional minor isomeric glycoforms.
authors.affiliation: Clinical Research Centre, Karolinska Institutet, Sweden.
authors.forename: Håkan H
authors.initials: HH
authors.lastname: Yildirim
authors.forename: Derek W
authors.initials: DW
authors.lastname: Hood
authors.forename: E Richard
authors.initials: ER
authors.lastname: Moxon
authors.forename: Elke K H
authors.initials: EK
authors.lastname: Schweda
mesh_terms: D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis; D006193:Haemophilus influenzae / Q000737:chemistry* / Q000145:classification; D008050:Lipid A / Q000737:chemistry; D008070:Lipopolysaccharides / Q000737:chemistry*; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000737:chemistry; D017421:Sequence Analysis; D012703:Serotyping; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D002241:Carbohydrates; D008050:Lipid A; D008070:Lipopolysaccharides; D009844:Oligosaccharides