FIG 2.

The Δfur single mutant is susceptible to killing by NO˙ and is rescued by iron chelation. (A) Percent survival of S. aureus Newman regulator mutants 8 h after exposure to 5 mM DETA-NO in LBGT medium (n = 3; error bars show SEM). (B) Percent survival of S. aureus Newman regulator mutants 1 h after exposure to 20 mM peroxide in LBGT medium (n = 3; error bars show SEM). (C and D) Percent survival (C) and growth (D) of WT Newman and Δfur strains 4 h after exposure to a mixture of 10 mM NOC-12 and 1 mM DEA-NO in LBGT medium with or without 200 μM 2,2′-dipyridyl (DIP). NO˙ was added at an OD₆₅₀ of 0.15 (t₀) (n = 3; error bars show SEM). (E) Hydroxyl radical formation was measured by detecting the fluorescence of hydroxyphenyl fluorescein (HPF) dye in the WT and the Δfur mutant following 2 h of aerobic growth, exposure to a 1 mM peroxide, or exposure to a NO˙ mixture (10 mM NOC-12, 1 mM DEA-NO). Relative fluorescence units (RFU) are normalized to the OD₆₅₀ (data were pooled from two separate experiments for n of 4; error bars show SEM). Significance for panels C and E was determined by a two-way analysis of variance test (ANOVA) with a post hoc Bonferroni multiple-comparison test (*, P ≤ 0.05; **, P ≤ 0.01). n.s., nonsignificant.