Effects of compounds on AgrA DNA-binding activity. Electrophoretic mobility shift assays were performed with AgrAC, its target DNA duplex and the indicated concentrations of A, 4-phenoxyphenol, B, 9H-xanthene-9-carboxylic acid, C, 2-(4-methylphenyl)-1,3-thiazole-4-carboxylic acid, D, [5-(2-thienyl)-3-isoxazolyl]methanol and E, 4-hydroxy-2,6-dimethylbenzonitrile. DNA incubated with or without AgrAC in the absence of compound are shown as positive and negative controls, respectively.