Expanded genomic map of Campylobacter jejuni UA580 and localization of 23S ribosomal rRNA genes by I-CeuI restriction endonuclease digestion.

The genomic map of Campylobacter jejuni UA580 was expanded and more precisely constructed using I-CeuI, Sal/I and SmaI restriction endonucleases in conjunction with pulsed-field gel electrophoresis (PFGE). The presence of three fragments after digestion with I-CeuI confirmed the presence of three copies of the 23S ribosomal rRNA (rrl) gene. The genome size of Campylobacter jejuni UA580 was determined to be 1725 +/- 5.9 kbp by I-CeuI with fragment sizes of 1053 +/- 4.4, 361 +/- 2.7 and 311 +/- 3.6 kbp. Analysis of a PCR product from C. jejuni UA580 23S rRNA gene showed that I-CeuI did cut within the gene. The precise locations of the three genes were determined using I-CeuI with two copies of the 23S and 5S rRNA genes located separately from the 16S rRNA gene whereas the third copy of the 23S and 5S rRNA genes had a closer linkage to a 16S rRNA gene copy. Homologous gene probes were used to map additional genes and allowed the realignment of a few previously mapped genes on the chromosome. Other strains of C. jejuni were also cut into three fragments with I-CeuI, which generated variable PFGE patterns.