MavR stabilizes the eutR transcript. (A) Northern blot of eutR transcripts expressed from pBAD-eutR::His in WT and ΔmavR at indicated time points before or after addition of rifampicin. 16S rRNA is the loading control. (B) Relative quantification of eutR expression in WT and ΔmavR prior to addition of rifampicin (time 0, in panel (A)), N = 3. (C) Decay curves of eutR RNA in WT and ΔmavR. The signal obtained at 0 min. was set to 1 for each strain, and the amount of RNA remaining at each timepoint was plotted on the y-axis versus time on the x-axis. The time point at which 50% of the eutR mRNA had been decayed (dashed line) was calculated to determine the half-life (t1/2), N = 3. (D) Half-life of eutR expressed from pBAD-eutR::His. N = 3. (E) Northern blot of eutR transcripts expressed from pBAD-eutR::His in WT, ΔmavR, rneΔCTD and ΔmavR rneΔCTD. (F) RT-qPCR of eut gene expression in WT and ΔmavR, N = 3. (G) RT-qPCR of eut gene expression in rneΔCTD and ΔmavR rneΔCTD, N = 3. For (B), (D), (F) and (G), bars represent the mean and error bars indicate SEM. ns P > 0.05, * P < 0.05, ** P < 0.01 (Student's two-sample t-test). (H) In vitro cleavage of eutR by N-Rne in the absence or presence of MavR. (I) Model: MavR interaction with the eutR transcript protects eutR from RNase E-mediated degradation. Stabilized eutR transcripts result in maximal EutR expression and EutR-dependent activation of eut expression.