@article{mbs:/content/journal/micro/10.1099/00221287-139-4-695, author = "Mcdevitt, Damien and Wann, Elisabeth R. and Foster, Timothy J.", title = "Recombination at the coagulase locus in Staphylococcus aureus: plasmid integration and amplification", journal= "Microbiology", year = "1993", volume = "139", number = "4", pages = "695-706", doi = "https://doi.org/10.1099/00221287-139-4-695", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-139-4-695", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "The integrating plasmid pCOA18, comprising pUC18 linked to a mutated coagulase (coa) gene from Staphylococcus aureus, and constructed by substituting coa sequences with a tetracycline (Tc)-resistance marker (∆coa::Tcr), was transformed into Staphylococcus aureus RN4220, where it underwent recombination with the chromosomal coa locus. Allele-replacement mutants were recovered at a low frequency directly after transformation. The majority of transformants carried pCOA18 integrated in the chromosome by a single Campbell-type recombination event. The majority of integrants contained tandem repeats of pCOA18 and expressed high levels of resistance to Tc (> 30 μg ml−1) compared to the single-copy integrants and allele-replacement mutants (15 μg ml−1). Transduction of a single-copy integrant to a Coa+ recipient allowed the cointegrant to be resolved and allele-replacement recombinants to be selected. In addition, growth of a single-copy integrant on high concentrations of Tc (> 30 μg ml−1) selected for amplified derivatives at a frequency of 10−5. It was estimated that up to 19 copies of pCOA18 could occur in a tandem array in the chromosome.", }