The Staphylococcus-Specific Gene rsr Represses agr and Virulence in Staphylococcus aureus

The expression of virulence factors in Staphylococcus aureus is tightly coordinated by a vast network of regulatory molecules. In this report, we characterize a genetic locus unique to staphylococci called rsr that has a role in repressing two key virulence regulators, sarR and agr . Using strain SH1000, we showed that the transcription of virulence effectors, such as hla , sspA , and spa , is altered in an rsr mutant in a way consistent with agr upregulation. Analysis of RNAIII expression of the agr locus in rsr and rsr-sarR mutants indicated that rsr likely contributes to agr expression independently of SarR. We also provide evidence using a murine model of S. aureu s skin infection that the effects mediated by rsr reduce disease progression.