FIG 2.

The ΔsrrAB phenotype requires srrAB-dependent cidABC expression. (A) S. aureus UAMS-1 (WT) and isogenic ΔsrrAB, ΔcidABC, and ΔsrrAB ΔcidABC mutant cell viabilities (mean ± SEM) were monitored every 24 h over a period of 5 days in TSB plus 35 mM glucose. Cultures were grown at 37°C under aerobic conditions. (B) S. aureus cells containing a cidABC promoter fused to lacZ were grown to postexponential phase and assayed for β-galactosidase activity. (C) Electrophoretic mobility shift assays (EMSAs) were performed using increasing amounts of purified SrrA protein and biotin-labeled cidABC promoter DNA as a target. Reaction mixtures were incubated for 30 min at room temperature and separated in a 6% TBE polyacrylamide gel.