IDENTIFICATION AND CHARACTERIZATION OF AN INTERVENING SEQUENCE WITHINTHE 23S RIBOSOMAL-RNA GENES OF CAMPYLOBACTER-JEJUNI

Campylobacter jejuni is a significant cause of bacterial enteritis in humans. Three of seven C. jejuni isolates examined were found to conta in fragmented 23S rRNA. The occurrence of fragmented 23S rRNA correlat ed with the presence of an intervening sequence (IVS) within the 23S r RNA genes. The IVS is 157 nucleotides in length and replaces an eight nucleotide sequence in the 23S rRNA genes of C. jejuni isolates that c ontain intact 23S rRNA. The two ends of the IVS share 31 bases of comp lementarity that could form a stem-loop structure. Fragmentation of th e 23S ribosomal RNA results from the excision of the IVS from the tran scribed RNA; the 3' cleavage site maps within the putative stem-loop f ormed by the IVS. Southern hybridization analysis revealed that the IV S is not present in the genomes of isolates that contain intact 23S rR NA, suggesting that the IVS is not derived from Campylobacter chromoso mal sequences. The C. jejuni IVS is located at a position analogous to that of the IVSs found in both Salmonella and Yersinia spp.