Multiple antibiotic resistance protein MarR (MarR)

Multiple antibiotic resistance protein MarR is a key transcriptional regulator in bacteria, particularly known for its role in mediating resistance to multiple antibiotics, oxidative stress, and organic solvents [1, 5, 13]. It is the prototypical member of the MarR family of transcription factors, characterized by a winged helix-turn-helix (wHTH) DNA-binding domain [2, 16]. Functioning primarily as a homodimeric repressor, MarR binds to the operator region of the marRAB operon, thereby limiting the production of the global activator MarA [5, 12, 15]. In the presence of specific ligands such as salicylate or certain environmental stressors, MarR undergoes allosteric changes that cause it to dissociate from the DNA [2, 13]. This dissociation allows for the upregulation of multidrug efflux pumps, such as AcrAB-TolC, and the downregulation of porins, facilitating a survival response [12, 15]. This regulatory mechanism makes MarR a critical determinant of clinical antibiotic resistance in pathogens like Escherichia coli and Staphylococcus aureus [1, 9, 13]. Consequently, it is considered an attractive target for novel antimicrobial strategies aimed at preventing the induction of resistance pathways [1, 5, 6].

Other names

Multiple antibiotic resistance regulatorRepressor of the marRAB operoncfxBinaRsoxQ

MarR functions as a transcriptional repressor of the marRAB operon; allosteric inactivation by small-molecule ligands or oxidation induces derepression of resistance genes [5, 6, 13].