Isolimonic acid requires QseA to repress ler. (A) Expression of ler in ΔqseA mutant and ΔqseA mutant supplemented with pqseA.The expression was monitored 30 min after addition of preconditioned media and 100 μg/ml isolimonic acid. (B) AI-3 induced β-galactosidase activity in TEVS232 supplemented with qseA (AV46). Asterisk denotes significant (p<0.05) difference from solvent control (DMSO). (C) Expression of qseA in presence of 100 μg/ml isolimonic acid. Fold change values were calculated over EHEC grown in presence of DMSO. The data represents mean ±SD of triplicate experiment.