Figure 4.
Inducer-dependent orthogonality of the YpItcR/Pccl inducible system. (A) Compounds that were investigated for cross-induction with the YpItcR/Pccl inducible system: itaconic acid (1), succinic acid (2), d-malic acid (3), l-malic acid (4), fumaric acid (5), oxaloacetic acid (6), l-aspartic acid (7), methylsuccinic acid (8), mesaconic acid (9), citraconic acid (10), α-ketoglutaric acid (11), l-glutamic acid (12), acetic acid (13), propionic acid (14), butyric acid (15), 3-butenoic acid (16), valeric acid (17), acrylic acid (18), methacrylic acid (19), tiglic acid (20), citric acid (21), cis-aconitic acid (22), trans-aconitic acid (23), tricarballylic acid (24), isocitric acid (25). (B) Normalized fluorescence (in %) of E. coli MG1655 harboring the YpItcR/Pccl inducible system 12 hours after addition of different compounds at a final concentration of 5 mM, relative to the fluorescence output obtained by adding 5 mM itaconate. (−) uninduced sample. Error bars represent standard deviations of three biological replicates. Asterisks indicate statistically significant induction values for p < 0.01 (unpaired t test).