title: Sialic acid in the lipopolysaccharide of Haemophilus influenzae: strain distribution, influence on serum resistance and structural characterization.
abstract: A survey of Haemophilus influenzae strains indicated that around one-third of capsular strains and over two-thirds of non-typeable strains included sialic acid in their lipopolysaccharides (LPS). Mutation of the CMP-Neu5Ac synthetase gene (siaB) resulted in a sialylation-deficient phenotype. Isogenic pairs, wild type and siaB mutant of two non-typeable strains were used to demonstrate that sialic acid influences resistance to the killing effect of normal human serum but has little effect on attachment to, or invasion of, cultured human epithelial cells or neutrophils. We determine for the first time the site of attachment of sialic acid in the LPS of a non-typeable strain and report that a small proportion of glycoforms include two sialic acid residues in a disaccharide unit.
authors.affiliation: Molecular Infectious Diseases Group, University of Oxford Department of Paediatrics, Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK. dhood@molbiol.ox.ac.uk
authors.forename: D W
authors.initials: DW
authors.lastname: Hood
authors.forename: K
authors.initials: K
authors.lastname: Makepeace
authors.forename: M E
authors.initials: ME
authors.lastname: Deadman
authors.forename: R F
authors.initials: RF
authors.lastname: Rest
authors.forename: P
authors.initials: P
authors.lastname: Thibault
authors.forename: A
authors.initials: A
authors.lastname: Martin
authors.forename: J C
authors.initials: JC
authors.lastname: Richards
authors.forename: E R
authors.initials: ER
authors.lastname: Moxon
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002240:Carbohydrate Sequence; D002460:Cell Line; D004187:Disaccharides / Q000737:chemistry; D004351:Drug Resistance / Q000235:genetics; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics*; D008070:Lipopolysaccharides / Q000737:chemistry*; D008969:Molecular Sequence Data; D009154:Mutation; D019158:N-Acetylneuraminic Acid / Q000032:analysis; D000216:N-Acylneuraminate Cytidylyltransferase; D009504:Neutrophils; D009844:Oligosaccharides / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D004187:Disaccharides; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D000216:N-Acylneuraminate Cytidylyltransferase; C091607:SiaB protein, Neisseria meningitidis; D019158:N-Acetylneuraminic Acid