Figure 4.

Anti-FASII adaptation confers oxidative stress resistance, and is accelerated by prior exposure to peroxide stress

(A) Stress response heatmap. Results are shown for anti-FASII adaptation medium (SerFA; see Table S1 for all test conditions). Sampling times (h) are indicated above green steps. Gene names and functional categories are at right. Heatmap (scale at left) is determined relative to weighted value for each protein (navy, down-represented; yellow, up-represented; see STAR Methods for analyses).

(B) S. aureus anti-FASII adaptation confers increased H₂O₂ resistance. Upper: USA300 non-treated (NT, orange bar) and AFN-1252-adapted overnight cultures (AD, green bar) were challenged with 0.5 mM H₂O₂ for 5 h, and CFUs were determined; means and standard errors are shown. ∗∗, p < 0.01. Lower: Lawns of NT and AD cultures (100 μL of dilutions adjusted to OD₆₀₀ = 0.1) were prepared on SerFA solid medium, and plates were spotted with 1.5 mm H₂O₂ and 4 nm (1.5 μg) AFN-1252, and photographed after 48 h incubation at 37°C. Representative of 3 independent assays.

(C) Priming S. aureus with H₂O₂ accelerates anti-FASII adaptation and requires PerR. Upper: USA300 (WT) and perR (SAUSA300_1842) mutant SerFA cultures were grown overnight without or with 0.5 mM H₂O₂. Cultures were diluted (OD₆₀₀ = 0.1) in SerFA without or with 0.5 μg/mL AFN-1252, and growth was monitored. Results are shown for biological triplicates. H₂O₂ –primed samples, without or with AFN addition at T0 are as indicated. Lower: FA profiles of indicated strains harvested at 6 h post-anti-FASII treatment (arrow in “C”). In green, FA profile of fully adapted H₂O₂-pretreated cultures at 10 h, shown here for perR and non-distinguishable from WT. 1, 2, and 3, eFAs present in SerFA medium (respectively C14, C16, and C18:1). At left of each profile, proportions of incorporated eFAs (%) are the average of two independent measurements (<3% difference between replicates).