FIG. 7.

Proposed mechanism of rsr-mediated gene regulation. rsr represses both sarR and agr during the late exponential phase. The repressive effects on agr by rsr during the late exponential phase are shown with regard to hla, sspA, and spa transcription. It is unclear whether rsr represses agr directly or via an as-of-yet-unidentified regulator. The repression of agr contributes to the repression of both hla and sspA and to the activation of spa. Together, these regulatory changes are predicted to result in a net decrease in virulence. The genetic locus rsr thus acts independently of SarR to inhibit agr expression.