The iron-sensing aconitase B binds its own mRNA to prevent sRNA-induced mRNA cleavage.
Bottom Line: In Escherichia coli, aconitase B (AcnB) is a typical moonlighting protein that can switch to its apo form (apo-AcnB) which favors binding its own mRNA 3'UTR and stabilize it when intracellular iron become scarce.Whereas RyhB can block acnB translation initiation, RNase E-dependent degradation of acnB was prevented by apo-AcnB binding close to the cleavage site.This previously uncharacterized regulation suggests an intricate post-transcriptional mechanism that represses protein expression while insuring mRNA stability.
Affiliation: Department of Biochemistry, RNA Group, University of Sherbrooke, 3201 Jean Mignault Street, Sherbrooke, Quebec J1E 4K8, Canada.Show MeSH
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Mentions: To evaluate the effect RyhB on AcnB expression, we monitored AcnB levels by western blots and compared the results to native AcnB from WT and ΔryhB cells grown under Fe starvation. Unexpectedly, AcnB levels remained stable over time when RyhB was induced in the presence of Dip (Figure 6A, left panel). In marked contrast, we observed a significant accumulation of AcnB (3.6-fold increase) in ΔryhB cells 2 h after Dip treatment (Figure 6A, right panel). These results suggested that RyhB expression significantly repressed AcnB translation when cells grew under low Fe conditions.
Affiliation: Department of Biochemistry, RNA Group, University of Sherbrooke, 3201 Jean Mignault Street, Sherbrooke, Quebec J1E 4K8, Canada.