Unusual features in organisation of capsular polysaccharide-related genes of C. jejuni strain X

•Targeted PCR based-procedure for sequencing of large DNA clusters•Unusual features of a C. jejuni cps gene cluster discovered•Mechanisms of generation of variant capsular polysaccharides suggested

PCR probing of the genome of Campylobacter jejuni strain X using conserved capsular polysaccharide (CPS)-related genes allowed elucidation of a complete sequence of the respective gene cluster (cps). This is the largest known Campylobacter cps cluster (38 kb excluding flanking kps regions), which includes a number of genes not detected in other Campylobacter strains. Sequence analysis suggests genetic rearrangements both within and outside the cps gene cluster, a mechanism which may be responsible for mosaic organisation of sugar transferase-related genes leading to structural variability of the capsular polysaccharide (CPS).