Figure 7.

Common regulatory networks of 3′ UTR-derived sRNAs. (A) In V. cholerae, the transcription factor FadR activates the expression of FarS and its parental mRNA fabB, of which the latter is involved in fatty acid synthesis. Simultaneously, FadR and FarS repress fadE expression that is part of the opposing β-oxidation pathway for fatty acids. Thus, this mixed feed-forward loop enables an efficient fatty acid metabolism. (B)The autoregulatory sRNA OppZ ensures a proper balance of the different proteins of the Opp peptide uptake system in V. cholerae. Through causing premature transcription termination of its parental mRNA, for all but the peptide-binding protein OppA, OppZ limits expression of oppBCDF as well as itself. (C) Mixed feed-forward loops can also be involved in the regulation of stress. As exemplified by the CpxR-dependent protein CpxP and sRNA CpxQ of the Enterobacteriales. Through translational inhibtion of diverse IMPs, CpxQ reduces the CpxR-mediated transcription of CpxP as well as the sRNA itself. Both components of the Cpx pathway ensure a reduction of misfolded IMPs and thus alleviate IM stress.