Figure 1
From: CsrA and its regulators control the time-point of ColicinE2 release in Escherichia coli
Time between toxin production and release. (A) The regulatory network controlling the delay between ColicinE2 production (cea) and release (cel) in CWT. The operon expresses the genes cea (ColicinE2), cei (immunity protein) and cel (protein inducing cell lysis). In the reporter plasmid, the genes cea and cel are replaced by genes encoding the fluorescent proteins YFP and CFP, respectively. The transcriptional repressor LexA inhibits expression of the operon. Cell stress causes RecA-mediated auto-cleavage of LexA dimers. Subsequently, a short cea-cei and a long cea-cei-cel mRNA are produced (T1, T2 = transcriptional terminators). Expression of cel is further regulated post-transcriptionally by binding of CsrA to the Shine-Dalgarno sequence (SD, depicted in blue) upstream to the cel gene. CsrA itself is regulated by two sRNAs, CsrB and CsrC. (B) Plasmids present in the two reporter strains CREP1 and SREP1. The CREP1 strain carries both the reporter plasmid pMO3 and pColE2-P9. The SREP1 strain carries only the reporter plasmid. (C) Dependence of the delay between ColicinE2 production and release by CREP1 (black) and SREP1 (grey) on the level of external stress (MitC concentration). (D) Average delay between ColicinE2 production and release by CREP1 (black) and SREP1 strains (grey). Error bars depict the standard error of the mean (SEM).
