Figure 4.

RyhB protects cirA mRNA from degradation by activating its translation. (A) Effect of arabinose-induced RyhB on cirA′-lacZ transcriptional fusion and on cirA′-′lacZ translational fusion in a Δfur ΔryhB background. Cells were grown in LB medium and 0.1% arabinose was added at an OD₆₀₀ of 0.1. Specific β-galactosidase activity from three independent cultures was then measured 3 h later. Mean and standard deviation (s.d.) values are shown. Empty vector pNM12 was used as a control. (B) β-Galactosidase assay of cirA′-lacZ transcriptional fusion and cirA′-′lacZ translational fusion in WT and ΔryhB cells grown in M63 iron-free glucose minimal medium at an OD₆₀₀ of 0.6. Specific β-galactosidase activity from three independent cultures was measured. Mean and s.d. values are shown. (C) Effect of arabinose-induced RyhB on cirAmutAUG′-lacZ transcriptional fusion in a Δfur ΔryhB background. Cells were grown in LB medium and 0.1% arabinose was added at an OD₆₀₀ of 0.1. Specific β-galactosidase activity from three independent cultures was then measured 3 h later. Mean and s.d. values are shown. Empty vector pNM12 was used as a control. (D) β-galactosidase assay of cirAmutAUG′-lacZ transcriptional fusion in WT and ΔryhB cells grown in M63 iron-free glucose minimal medium at an OD₆₀₀ of 0.6. Specific β-galactosidase activity from three independent cultures was measured. Mean and s.d. values are shown.