FIG 4.

Transcription levels of fur and two fur-like genes in the WT and ΔirrB strains under high-iron (A) and low-iron (B) conditions. Means were compared using Student's t test; differences with P values of <0.05 were considered significant. Under high-iron conditions, the irrA transcription level was 5.5-fold higher in the ΔirrB strain than in the WT (P < 0.05). Under low-iron conditions, the irrA level in the ΔirrB strain was 2-fold higher than that in the WT, but the irrC and fur levels were lower.