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
Related in: MedlinePlus
Mentions: The data described above suggested that binding of AcnB to acnB 3′UTR interfered with RyhB-induced degradation of the mRNA. To add support to this interpretation, we constructed a transcriptional fusion (acnB2688-lacZ) comprising all but the last two codons of acnB ORF (Figure 3A). The reasoning behind the use of this construct was that it would allow RyhB binding to the translation initiation region (Supplementary Figures S2A, S2B and S2C) but would prevent apo-AcnB binding at the 3′UTR of acnB mRNA. The fusion acnB2688-lacZ was tested in cells grown under usual conditions (Figure 1A). Northern blots showed that acnB2688-lacZ remained resistant to the expression of RyhB after 10 min of induction (Figure 4A, lanes 1 and 2).
Affiliation: Department of Biochemistry, RNA Group, University of Sherbrooke, 3201 Jean Mignault Street, Sherbrooke, Quebec J1E 4K8, Canada.