FIG 3.

Role of the agr system in hysA gene regulation. Cultures of various LAC strains were grown for 8 h, spent medium was prepared, and the hyaluronidase specific activity in each sample was measured. (A) To assess the agr and SigB interaction, activity was measured in the WT, agr and sigB single mutant, and agr sigB double mutant strains and plotted. (B) To assess the agr and CodY interaction, activity was measured in the WT, agr and codY single mutant, and codY agr double mutant strains. For panels A and B, statistical significance (****, P < 0.0001) was determined by Student's t test. (C) Hyaluronidase specific activity for the WT containing the empty vector (black bars) or RNAIII under the control of a tetracycline-inducible promoter (gray bars). Student's t test was used to determine statistical significance (**, P < 0.01; ****, P < 0.0001). (D) Model for SigB and CodY regulation of HysA through the agr system.