Identification and structural characterization of a sialylated lacto-N-neotetraose structure in the lipopolysaccharide of Haemophilus influenzae.
A sialylated lacto-N-neotetraose (Sial-lNnT) structural unit was identified and structurally characterized in the lipopolysaccharide (LPS) from the genome-sequenced strain Rd [corrected] (RM118) of the human pathogen Haemophilus influenzae grown in the presence of sialic acid. A combination of molecular genetics, MS and NMR spectroscopy techniques showed that this structural unit extended from the proximal heptose residue of the inner core region of the LPS molecule. The structure of the Sial-lNnT unit was identical to that found in meningococcal LPS, but glycoforms containing truncations of the Sial-lNnT unit, comprising fewer residues than the complete oligosaccharide component, were not detected. The finding of sialylated glycoforms that were either fully extended or absent suggests a novel biosynthetic feature for adding the terminal tetrasaccharide unit of the Sial-lNnT to the glycose acceptor at the proximal inner core heptose.
Institute for Biological Sciences, National Research Council, Ottawa, Canada. Andrew.Cox@nrc.ca
Andrew D
AD
Cox
Derek W
DW
Hood
Adele
A
Martin
Katherine M
KM
Makepeace
Mary E
ME
Deadman
Jianjun
J
Li
Jean-Robert
JR
Brisson
E Richard
ER
Moxon
James C
JC
Richards
D002240:Carbohydrate Sequence; D006193:Haemophilus influenzae / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000032:analysis*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification
D008070:Lipopolysaccharides; D009844:Oligosaccharides; C013084:lacto-N-neotetraose; D019158:N-Acetylneuraminic Acid