Cloning, mutation and distribution of a putative lipopolysaccharide biosynthesis locus in Campylobacter jejuni

A region encoding ORFs with homology to known lipopolysaccharide (LPS) bios ynthesis genes was isolated from two strains of Campylobacter jejuni. One o f the strains produces LPS, but the second strain is reported to produce on ly lipooligosaccharide (LOS) and therefore lacks the O-chain. The two strai ns shared six predicted ORFs, but an additional ORF, orfE, of unknown funct ion was identified in the LOS-producing strain. Mutation of the shared wbeE (rfbE) homologue (orfF) or deletion of five of the seven genes reduced cor e reactivity with specific antiserum without affecting O-chain production. Mutation of either the capD homologue (orfG) or the unique orfE had no dete ctable effect on LOS or LPS production. The presence or absence of orfE in 36 isolates of C. jejuni did not correlate with LOS/LPS phenotype or seroty pe. However, after insertion of orfE into a LPS-producing orfE-negative str ain the O-chain ladder was no longer detectable on Western blots. We were n ot able to disrupt the wbaP (rfbP) homologue (orfC) in C. jejuni.