Isolation of a repeated DNA sequence from Bordetella pertussis

A repeated DNA sequence in the genome of Bordetella pertussis has been demonstrated. At least 20 copies of this sequence could be observed in either BamHI or EcoRI restriction enzyme digests of chromosomal DNA; fragments carrying the repeated DNA sequence ranged in size from about 1.5 to 20 kbp. The repeated DNA sequence was cloned from two separate regions of the B. pertussis genome, as shown by restriction enzyme site maps of the two clones and by hybridization studies. A small number of differences in the pattern of hybridization of the repeated DNA sequence to chromosomal DNA from several strains of B. pertussis was observed. No repeated DNA sequences were observed in one strain each of B. parapertussis and B. bronchiseptica, and there was no hybridization of B. pertussis DNA to Escherichia coli chromosomal DNA. The repeated DNA sequence was subcloned on a 2.54 kbp BamHI fragment from one of the two original clones. Restriction enzyme digests and hybridization studies showed that the repeated DNA sequence was about 1 kbp in size and had a single, internal ClaI site.