Figure 5

Time-point of ColicinE2 release is regulated by the global carbon storage regulator CsrA. (A) CsrA controls the delay between toxin production and release. This mechanism prevents premature release of ineffective toxin concentrations. CsrA abundance is regulated by several components: the long mRNA transcribed from the pColE2-P9 plasmid and the reporter plasmid pMO3 (or pMO8), the sRNAs CsrB and CsrC, and the newly discovered regulatory element ssDNA originating and accumulating from autonomous rolling circle plasmid replication. (B) Our experimental and theoretical data emphasize the importance of the amount of long mRNA that correlates with the plasmid copy number, as well as the presence of ssDNA as CsrA sequestering elements affecting the cea-cel delay. C strains are shown in black, S strains are shown in grey. The grey sketched area depicts the area of expected delay times of all strains in dependence to the plasmid copy number only. Please note that due to the fact that at low plasmid copy numbers many cells do not lyse (nl) these delay times cannot be given as an exact value, but are estimated to lie in the depicted grey area. Red dots represent the values of the theoretical analysis in the absence of ssDNA (so plasmid copy number effect only), green markers represent the theoretical values in the presence of ssDNA, which is the case for all C strains.