期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 285, 期 45, 页码 34330-34336出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M110.166314
关键词
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资金
- National Institutes of Health, NIAID [AI057159]
- New England Center of Excellence in Biodefense and Emerging Infectious Disease
3-Deoxy-D-manno-octulosonic acid (Kdo) is an eight-carbon sugar ubiquitous in Gram-negative bacterial lipopolysaccharides (LPS). Although its biosynthesis is well described, no protein has yet been identified as a Kdo hydrolase. However, Kdo hydrolase enzymatic activity has been detected in membranes of Helicobacter pylori and Francisella tularensis and may be responsible for the removal of side-chain Kdo from the LPS core saccharides. We now report the identification of genes encoding a Kdo hydrolase in F. tularensis Schu S4 and live vaccine strain strains, in H. pylori 26695 strain and in Legionella pneumophila Philadelphia 1 strain. We have renamed the genes kdhA for keto-deoxyoctulosonate hydrolase A. Deletion of kdhA abolished Kdo hydrolase activity in membranes of F. tularensis live vaccine strain. The F. tularensis kdhA mutant synthesized a core oligosaccharide containing a Kdo disaccharide with one of the Kdo residues being a terminal side chain. This side-chain Kdo monosaccharide was absent in the wild-type core oligosaccharide. Expression in Escherichia coli of recombinant KdhA from F. tularensis, H. pylori, and L. pneumophila resulted in a reduction of membrane-associated side-chain Kdo. The identification of this previously faceless enzyme will accelerate study of the biosynthetic basis and biologic impact for postbiosynthetic LPS structural modification.
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