Previous studies have identified mutant strains of Staphylococcus aureus that have deficiencies in genetic recombination and DNA repair. Although these phenotypes were tentatively attributed to mutations within the S. aureus recA gene, experimental evidence to confirm this has never been reported. To characterize recA from S. aureus, we first isolated transposon insertion mutations that were in close proximity to the recA-like mutation (uus-568) in strain 112 UVS-1. This allowed for the mobilization of the uus-568 mutation into strain RN4220, the common laboratory strain of S. aureus. Next, using Bacillus subtilis recA as a probe, we cloned S. aureu recA and determined its nucleotide sequence. The deduced amino acid (aa) sequence of RecA contained 347 aa and was 74% identical to B. subtilis RecA. Using a cloned DNA fragment originating from within S. aureu recA, we then constructed a recA null mutant strain, designated KB 103, which exhibited the same phenotypic characteristics imposed by the uvs-56S mutation in the same background. Furthermore, genetic and physical mapping of S. aureu recA placed it in the same region as the uus-568 mutation. These data strongly suggest that these mutations represent different alleles of the same recA gene. RecA; recombination; DNA repair; Campbell integration; Cheo Box.
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