title: The CMP-legionaminic acid pathway in Campylobacter: biosynthesis involving novel GDP-linked precursors.
abstract: The sialic acid-like sugar 5,7-diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-nonulosonic acid, or legion-aminic acid, is found as a virulence-associated cell-surface glycoconjugate in the Gram-negative bacteria Legionella pneumophila and Campylobacter coli. L. pneumophila serogroup 1 strains, causative agents of Legionnaire's disease, contain an alpha2,4-linked homopolymer of legionaminic acid within their lipopolysaccharide O-chains, whereas the gastrointestinal pathogen C. coli modifies its flagellin with this monosaccharide via O-linkage. In this work, we have purified and biochemically characterized 11 candidate biosynthetic enzymes from Campylobacter jejuni, thereby fully reconstituting the biosynthesis of legionaminic acid and its CMP-activated form, starting from fructose-6-P. This pathway involves unique GDP-linked intermediates, likely providing a cellular mechanism for differentiating between this and similar UDP-linked pathways, such as UDP-2,4-diacetamido-bacillosamine biosynthesis involved in N-linked protein glycosylation. Importantly, these findings provide a facile method for efficient large-scale synthesis of legionaminic acid, and since legionaminic acid and sialic acid share the same D-glycero-D-galacto absolute configuration, this sugar may now be evaluated for its potential as a sialic acid mimic.
authors.affiliation: Institute for Biological Sciences, National Research Council, Ottawa, Ontario, K1A 0R6 Canada. ian.schoenhofen@nrc-cnrc.gc.ca
authors.forename: Ian C
authors.initials: IC
authors.lastname: Schoenhofen
authors.forename: Evgeny
authors.initials: E
authors.lastname: Vinogradov
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Whitfield
authors.forename: Jean-Robert
authors.initials: JR
authors.lastname: Brisson
authors.forename: Susan M
authors.initials: SM
authors.lastname: Logan
mesh_terms: D016123:Campylobacter jejuni / Q000378:metabolism*; D003568:Cytidine Monophosphate / Q000378:metabolism*; D005944:Glucosamine / Q000096:biosynthesis*; D006153:Guanosine Diphosphate / Q000096:biosynthesis* / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism*
chemical_list: C110570:5,7-diacetamido-8-O-acetyl-3,5,7,9-tetradeoxy-glycero-talo-nonulosonic acid; D012794:Sialic Acids; D006153:Guanosine Diphosphate; D003568:Cytidine Monophosphate; D005944:Glucosamine