Fig. 2. Endogenous ECFs can interfere with the performance of heterologous ECF switches. (IMAGE)
Caption
(A) The ECF profile of S. meliloti is compared to the heterologous ECF switches that were shown to be active in the Rm1021 wild type and/or the ECF/anti-σ-free strain. Phylogenetic groups are given on top. If 2 groups are listed, the first one refers to the initial classification [13] and the second one to the latest classification [12]. Numbers indicate the presence of one or more ecf genes from a certain phylogenetic group in the genome of S. meliloti. * is indicative of an active heterologous ECF switch. Red shaded boxes label shared phylogenetic ECF groups. (B) Performance of the ECF26-based switch in Rm1021 and the ECF/anti-σ-free strain and (C) Pecf26 activation by endogenous ECFs from the same phylogenetic group (RpoE1, RpoE3, RpoE4, and RpoE6) assayed in the ECF/anti-σ-free strain. The experimental setup in (B) and (C) corresponds to the setup described in Fig. 1A. IPTG at different concentrations (0, 50, and 500 μM) was used to induce ecf expression. Promoter activities were normalized to yield luminescence units per unit of OD600 (left y-axis). Each dot represents the mean response of 3 biological replicates 6 h after addition of IPTG. Arrow bars show standard deviation. Rectangular bars represent the average log2(fc) of promoter activity in the presence of 500 μM IPTG compared to the basal promoter activity in the absence of any heterologous ecf (right y-axis). The underlying data are given in Table S9.
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BioDesign Research
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