FIG 2.

SaeR and SaeS are necessary and sufficient to upregulate nuc when codY is knocked out. The indicated LAC strains were grown to exponential phase in tryptic soy broth (TSB) at which time nuc-gfp promoter activity (A) or secreted nuclease activity (B) was measured. The intracellular abundances of SaeR (C) and SaeS (D) were detected in the indicated strains by Western blot analysis using polyclonal antibodies raised against S. aureus proteins (top panel). Protein levels were normalized via BCA protein assay, and loading consistency was verified using Coomassie blue stains (see Fig. S5 in the supplemental material). Densitometric quantification (bottom panels) was performed using ImageJ software (National Institutes of Health). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001, Tukey multiple-comparison test after analysis of variance (ANOVA). <, indistinguishable from blank; ns, not significant; nd, not detected.