Fig 4.

NnrS protects the cellular iron pool from NO. (A) V. cholerae ΔhmpA and ΔhmpA ΔnnrS strains were inoculated into minimal medium with glucose and yeast extract in the presence of increasing concentrations of DETA-NONOate with (dashed lines) or without (solid lines) the iron chelator 2,2′-dipyridyl. Shown is the OD₆₀₀ at 10 h of growth, representative of two independent experiments. (B) Relative ferrous iron contents of ΔhmpA and ΔhmpA ΔnnrS strains in the presence (+NO) or absence (−NO) of DETA-NONOate. The error bars represent the standard deviations of the mean of three independent experiments. Statistical significance was determined by two-way ANOVA with Bonferroni's posttest to compare individual groups. **, P < 0.01; ***, P < 0.001.