Identification of a lipopolysaccharide alpha-2,3-sialyltransferase from Haemophilus influenzae: Mol.Microbiol.

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TypeArticle
Journal titleMol.Microbiol.
Volume39
Issue2
Pages341350; # of pages: 10
SubjectACID; analysis; assay; Blood Bactericidal Activity; Carbohydrate Sequence; chemistry; DISEASE; Electrophoresis,Capillary; enzymology; Escherichia; Escherichia coli; ESCHERICHIA-COLI; GENE; genetics; growth & development; Haemophilus; Haemophilus influenzae; HAEMOPHILUS-INFLUENZAE; Human; IDENTIFICATION; LIPOPOLYSACCHARIDE; Lipopolysaccharides; LPS; MAGNETIC; MAGNETIC-RESONANCE; mass spectrometry; MASS-SPECTROMETRY; metabolism; Methods; MOLECULAR; Molecular Sequence Data; MUTANT; MUTANTS; Mutation; N-Acetylneuraminic Acid; NMR; NUCLEAR; Nuclear Magnetic Resonance; NUCLEAR-MAGNETIC-RESONANCE; RESONANCE; Sialyltransferases; SPECTROSCOPY; Spectrum Analysis,Mass; STRAIN; STRAINS; STRUCTURAL; structural analysis; STRUCTURAL-ANALYSIS; synthetic
AbstractWe have identified a gene for the addition of N-acetylneuraminic acid (Neu5Ac) in an alpha-2,3-linkage to a lactosyl acceptor moiety of the lipopolysaccharide (LPS) of the human pathogen Haemophilus influenzae. The gene is one that was identified previously as a phase-variable gene known as lic3A. Extracts of H. influenzae, as well as recombinant Escherichia coli strains producing Lic3A, demonstrate sialyltransferase activity in assays using synthetic fluorescent acceptors with a terminal galactosyl, lactosyl or N-acetyl-lactosaminyl moiety. In the RM118 strain of H. influenzae, Lic3A activity is modulated by the action of another phase-variable glycosyltransferase, LgtC, which competes for the same lactosyl acceptor moiety. Structural analysis of LPS from a RM118:lgtC mutant and the non-typeable strain 486 using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy confirmed that the major sialylated species has a sialyl-alpha-(2-3)-lactosyl extension off the distal heptose. This sialylated glycoform was absent in strains containing a lic3A gene disruption. Low amounts of sialylated higher molecular mass glycoforms were present in RM118:lgtC lic3A, indicating the presence of a second sialyltransferase. Lic3A mutants of H. influenzae strains show reduced resistance to the killing effects of normal human serum. Lic3A, encoding an alpha-2,3-sialyltransferase activity, is the first reported phase-variable sialyltransferase gene
Publication date
LanguageEnglish
AffiliationNRC Institute for Biological Sciences; National Research Council Canada
Peer reviewedNo
NRC numberHOOD2001A
NPARC number9361959
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Record identifierb3409f6b-2515-4c74-be6f-f0f96c4b92c7
Record created2009-07-10
Record modified2016-05-09
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