FIG 3.

Virulence gene regulation in GAS correlates with SpxA2 levels. (A) Quantitative real-time PCR (qRT-PCR) of selected targets in isogenic mutants with high (ΔliaF, ΔclpX) or low (ΔspxA2, ΔliaF ΔspxA2) SpxA2 levels. Strains were grown in nutrient-rich medium identical to conditions used for RNA-seq studies (mid-exponential growth) and in biological quadruplicates. *, P < 0.05 (Student’s t test). (B) qRT-PCR to assay speB transcript levels in isogenic mutant strains as in panel A. (C) Phos-Tag protein gel electrophoresis to assay CovR phosphorylation (CovR∼P) in isogenic mutant strains with high or low SpxA2 levels. Levels of phosphorylation for each mutant are indicated (relative to the wild-type [WT] strain), with red text indicating decreased CovR∼P relative to that in the WT.