| Autor: |
Hood DW; 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, Cox AD, Gilbert M, Makepeace K, Walsh S, Deadman ME, Cody A, Martin A, Månsson M, Schweda EK, Brisson JR, Richards JC, Moxon ER, Wakarchuk WW |
| Jazyk: |
angličtina |
| Zdroj: |
Molecular microbiology [Mol Microbiol] 2001 Jan; Vol. 39 (2), pp. 341-50. |
| DOI: |
10.1046/j.1365-2958.2001.02204.x |
| Abstrakt: |
We 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. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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