FIG 4.

Effect of cobalt stress on the expression of iron-responsive genes determined using qRT-PCR. Log-phase cells of the NTL4 (WT), PN094 (rirA mutation), and WK074 (irr mutation) strains grown in LB were either untreated or treated with CoCl₂ (250 or 500 μM), FeCl₃ (50 μM), or Dy (200 μM) for 15 min. The fold changes in gene expression (hmuT, shmR, fbpA, mbfA, sufS2, and fssA) are expressed relative to the untreated WT sample (LB, regarded as 1). The experiment was performed in biological triplicate, and the error bars indicate the standard deviations.