Alteration of the Repressor Activity of MarR, the Negative Regulator of the Escherichia coli marRAB Locus, by Multiple Chemicals In Vitro

MarR negatively regulates expression of the multiple antibiotic resistance operon (marRAB) in Escherichia coli. In this study, it was demonstrated that sodium salicylate, plumbagin, 2,4-dinitrophenol, and menadione–inducers of the marRAB operon in whole cells–all interfered with the repressor activity of MarR in vitro. It is proposed that these compounds can interact directly with MarR to affect its repressor activity.