title: Expression of a new disialyllacto structure in the lipopolysaccharide of non-typeable Haemophilus influenzae.
abstract: The structure of lipopolysaccharide (LPS) expressed by non-typeable Haemophilus influenzae (NTHi) strains 1008 and 1247 has been investigated by mass spectrometry and NMR analyses on O-deacylated LPS and core oligosaccharide material. Both strains express the conserved triheptosyl inner core, [l-α-d-Hepp-(1→2)-[PEtn→6]-l-α-d-Hepp-(1→3)-l-α-d-Hepp-(1→5)-[PPEtn→4]-α-Kdo-(2→6)-Lipid A] with PCho→6)-β-d-Glcp (GlcI) substituting the proximal heptose (HepI) at O-4. Strain 1247 expresses the common structural motifs of H. influenzae; globotetraose [β-d-GalpNAc-(1→3)-α-d-Galp-(1→4)-β-d-Galp-(1→4)-β-d-Glcp-(1→] and its truncated versions globoside [α-d-Galp-(1→4)-β-d-Galp-(1→4)-β-d-Glcp-(1→] and lactose [β-d-Galp-(1→4)-β-d-Glcp-(1→] linked to the terminal heptose of the inner core and GlcI. A genetically distinct NTHi strain, 1008, expresses identical structures to strain 1247 with the exception that it lacks GalNAc. A lpsA mutant of strain 1247 expressed LPS of reduced complexity that facilitated unambiguous structural determination of the oligosaccharide from HepI. By CE-ESI-MS/MS we identified disialylated glycoforms indicating disialyllactose [α-Neu5Ac-(2→8)-α-Neu5Ac-(2→3)-β-d-Gal-(1→4)-β-d-Glcp-(1→] as an extension from GlcI which is a novel finding for NTHi LPS.
authors.affiliation: Karolinska Institutet, Clinical Research Centre, Huddinge, Sweden.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Twelkmeyer
authors.forename: Peter K
authors.initials: PK
authors.lastname: Burström
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li
authors.forename: E
authors.initials: E
authors.lastname: Richard Moxon
authors.forename: Derek W
authors.initials: DW
authors.lastname: Hood
authors.forename: Elke K H
authors.initials: EK
authors.lastname: Schweda
mesh_terms: D002240:Carbohydrate Sequence; D006193:Haemophilus influenzae / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D008070:Lipopolysaccharides