FIG. 2.

Schematic representation of the C. jejuni 81-176 chromosomal region encoding relevant LOS genes. The overall genomic organization is similar to that of class B loci described by Gilbert and colleagues and Parker et al. (7, 28). The ORF designated waaC showed 87% identity and 88% similarity to WaaC (Cj1133) from the C. jejuni genome strain NCTC11168. The cat transposon insertion that was used to generate the mutation was at 677 bp from the translational start of the 1,029-bp waaC gene. The second ORF encoded a predicted protein with 99% identity to HtrB, a lipid A biosynthesis lauroyl acyltransferase, from C. jejuni strain GB11. The third ORF encoded a protein that showed 88% identity and 94% similarity to a putative two-domain glycosyltransferase of C. jejuni NCTC11168 (Cj1135). The fourth ORF exhibited 75% identity and 86% similarity to a putative β-1,3-galactosyltransferase from C. jejuni NCTC1168 (Cj1136). The 81-176 homolog of cgtB was slip stranded out of frame as cloned. This gene encodes a galactosyltransferase that has been shown to undergo phase variation in another strain to convert GM₂ to GM₁ mimics (20). Between Cj1136 and the cgtB homolog, there was no ORF of >174 bp, but BLASTX analysis revealed homology to a β-1,4-GalNAc transferase, similar to what has been reported for other class B LOS loci (7, 28).