Fig. S1.

(A) USA300 WT or essB-mutant cells were grown in TSB alone or in TSB supplemented with 2.5% nasal secretions (NS). (Left) Whole-cell lysates and supernatants were assessed for EsxA protein by Western blot. (Right) Bar graphs represent the quantitation of EsxA stimulation in whole cells and supernatants from two independent experiments. (B) USA300 cells were grown in TSB alone or in TSB supplemented with the indicated concentrations and types of serum. Whole-cell lysates were assessed for EsxA protein by Western blot. (C) (Right) Human serum was digested with trypsin, and the degree of proteolysis was assessed by simplyBlue stain (Applied Biosystems). (Left) USA300 cells were grown in TSB alone or in TSB supplemented with the indicated concentration of human serum. Whole-cell lysates were analyzed for EsxA protein by Western blot. (D) Human serum either was left untreated or was heat-inactivated by incubation at 55 °C for 30 min. USA300 cells were grown in TSB alone or in TSB supplemented with varying concentrations (20, 4, 0.8, or 0.16%) of untreated human serum or heat-inactivated human serum. Whole-cell lysates were assessed for EsxA protein by Western blot. (E) USA300, USA400, and Newman cells were grown in TSB alone or in TSB supplemented with 10 µM LA. Whole-cell lysates (Left) and supernatants (Right) were assessed for EsxA and RpoB protein by Western blot. (F) Human serum and LA were preincubated with varying concentrations of BSA (50, 5, or 0.5 mg/mL, or zero). USA300 cells were grown in TSB alone or in TSB supplemented with the BSA-treated 0.25% human serum (Left) or 10 µM LA (Right). Whole-cell lysates were assessed for EsxA protein by Western blot.