Fig 11.

Full-length SSR42 is required for full regulatory capacity. LACΔSSR42 cells were complemented with full-length SSR42 or bases 1 to 445 or 446 to 891 of SSR42 and evaluated for the ability of each construct to complement virulence factor expression in USA300. Virulence factor mRNA titers were determined by qRT-PCR for genes found to exhibit increased (A) or decreased (B) expression levels in ΔSSR42 cells with GeneChips. Results are presented as n-fold changes in ΔSSR42 (white), SSR42.1⁺ (diagonal), or SSR42.2⁺ (punctate) mRNA titers over LAC (black) levels, which were set to 1.0. An asterisk represents a statistically significant difference between LAC and the complemented strains (P < 0.05) determined by multiple comparisons of means using the Bonferroni-Holm correction. Error bars represent 1 standard deviation from the mean of each sample (n = 5). (C) Hemolytic capabilities of supernatants from stationary-phase LAC, ΔSSR42, and SSR42⁺ cell cultures were quantified by the measurement of A₄₀₅ due to heme liberated from lysed rabbit erythrocytes. Error bars represent 1 standard deviation from the mean of each sample (n = 5).