Recombination at the coagulase locus in Staphylococcus aureus: plasmid integration and amplification.
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 (delta 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 micrograms ml-1) compared to the single-copy integrants and allele-replacement mutants (15 micrograms 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 micrograms 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.
McDevitt
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Microbiology Department, Moyne Institute, Trinity College, Dublin, Ireland.
Wann
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Foster
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TJ
D000483:Alleles; D015139:Blotting, Southern; D003030:Coagulase / Q000235:genetics*; D005784:Gene Amplification; D005798:Genes, Bacterial; D016296:Mutagenesis; D010641:Phenotype; D010957:Plasmids; D011995:Recombination, Genetic; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000235:genetics*; D014161:Transduction, Genetic; D014170:Transformation, Genetic
D003030:Coagulase