Glycobiology Advance Access originally published online on March 24, 2004
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Glycobiology vol 14 no 6 pp. 537-546, 2004
Glycobiology vol. 14 no. 6 © Oxford University Press 2004; all rights reserved.
Characterization of the 
-1,2-N-acetylglucosaminyltransferase of Neisseria gonorrhoeae, a key control point in lipooligosaccharride biosynthesis
National Research Council of Canada, Institute for Biological Sciences, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 Canada
Received on January 8, 2004; revised on February 19, 2004; accepted on March 4, 2004
The biosynthesis of the lipooligosaccharide (LOS) in Neisseria meningitidis has a control point that regulates the extension of the alpha-chain on heptose (I) of the LOS. The gene that encodes the protein responsible for this control had been identified elsewhere, but the enzyme encoded by the gene was not characterized. We have now shown that this same control mechanism operates in the related species, Neisseria gonorrhoeae, using a gene knockout and subsequent characterization of the LOS species produced. We also cloned and expressed the enzyme from both of these pathogens. Using a synthetic acceptor substrate, we have shown unequivocally that the enzyme is an 
-1,2-N-acetylglucosaminyltransferase. Experiments with both the core oligosaccharide and the synthetic acceptors suggests that the addition of the -1,2-N-acetylglucosamine moiety on the heptose (II) residue precedes the addition of the ethanolamine phosphate at the O3 position on this heptose (II), and that in the absence of the -1,2-N-acetylglucosamine moiety leads to the addition of an extra ethanolamine phosphate on the heptose (II) residue. Our data do not support the hypothesis that ethanolamine phosphate at O3 of heptose (II) is added and is then required for the addition of the N-acetylglucosamine at O2 by the LgtK enzyme. This enzyme represents a control point in the biosynthesis of the LOS of this pathogen and is a potential target for therapeutic intervention.
1 To whom correspondence should be addressed; e-mail: warren.wakarchuk{at}nrc-cnrc.gc.ca
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