Figure 5.

Hfq represses cirA mRNA translation. (A) Northern blot analysis of Hfq effect on cirA mRNA levels. Strains EM1055 (WT), EM1238 (ΔryhB), EM1265 (Δhfq) and KP111 (Δhfq ΔryhB) were grown in M63 iron-free glucose minimal medium at an OD₆₀₀ of 0.6 and total RNA was extracted. Probes complementary to cirA and shiA open reading frames (ORFs) were used. (B) β-Galactosidase assay of cirA′-lacZ transcriptional fusion and cirA′-′lacZ translational fusion in Δhfq and Δhfq 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 standard deviation (s.d.) values are shown. (C) Northern blot analysis of arabinose-induced RyhB effect on cirA mRNA levels in Δfur ΔryhB Δhfq cells. Strains HS506 (Δfur ΔryhB) and HS518 (Δfur ΔryhB Δhfq), each carrying pBAD-ryhB or control plasmid pNM12, were grown in M63 iron-free glycerol minimal medium. Arabinose (0.1%) was added at an OD₆₀₀ of 0.3 and total RNA was extracted 10 min later. A probe complementary to cirA ORF was used. (D) Effect of arabinose-induced RyhB on cirA′-lacZ transcriptional fusion and cirA′-′lacZ translational fusion in a Δfur ΔryhB Δhfq background. Cells were grown in M63 iron-free glycerol minimal 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.

Source data for this figure is available on the online supplementary information page.

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