The genetic bases for the variation in the lipo-oligosaccharide of the mucosal pathogen, Campylobacter jejuni. Biosynthesis of sialylated ganglioside mimics in the core oligosaccharide.
We have compared the lipo-oligosaccharide (LOS) biosynthesis loci from 11 Campylobacter jejuni strains expressing a total of 8 different ganglioside mimics in their LOS outer cores. Based on the organization of the genes, the 11 corresponding loci could be classified into three classes, with one of them being clearly an intermediate evolutionary step between the other two. Comparative genomics and expression of specific glycosyltransferases combined with in vitro activity assays allowed us to identify at least five distinct mechanisms that allow C. jejuni to vary the structure of the LOS outer core as follows: 1) different gene complements; 2) phase variation because of homopolymeric tracts; 3) gene inactivation by the deletion or insertion of a single base (without phase variation); 4) single mutation leading to the inactivation of a glycosyltransferase; and 5) single or multiple mutations leading to "allelic" glycosyltransferases with different acceptor specificities. The differences in the LOS outer core structures expressed by the 11 C. jejuni strains examined can be explained by one or more of the five mechanisms described in this work.
Gilbert
Michel
M
Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Dr., Ottawa, Ontario K1A 0R6, Canada.
Karwaski
Marie-France
MF
Bernatchez
Stéphane
S
Young
N Martin
NM
Taboada
Eduardo
E
Michniewicz
Joseph
J
Cunningham
Anna-Maria
AM
Wakarchuk
Warren W
WW
D000595:Amino Acid Sequence; D016123:Campylobacter jejuni / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D016695:Glycosyltransferases / Q000235:genetics*; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation
D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D016695:Glycosyltransferases