BaeR is the primary regulator of the ethanol stress response [11]. Leblanc et al. identified two flavonoids and also sodium tungstate as novel inducers to BaeSR [12]. These new inducers are natural substrates of the MdtABC efflux pump, and they lead to much stronger induction of the BaeST response in an mdtA efflux pump mutant, while indole does not [12]. As a consequence of this sensing, BaeS is autophosphorylated, followed by the transfer of the phosphate group to BaeR [10], which is converted to an active form [7] that appears to recognize and bind a DNA sequence with a direct repeat symmetry [5]. BaeR exhibits high degrees of sequence similarity with the transcriptional regulators OmpR and PhoB [10] and belongs to the OmpR subfamily whose members contain a DNA-binding motif in the C-terminal domain [10]. The BaeSR, PhoBR, and CreBC two-component systems have been shown to interact in the regulation of gene expression [4]. BaeR suppresses envZ and phoR/creC mutations [10]. The crystal structure of the unphosphorylated dimeric form of BaeR has been determined [13]. BaeR is not an essential protein [14]. BaeR overproduction decreases the expression levels of outer membrane channel TolC, the global regulators MarA and Rob, as well as cephalosporin susceptibility in an acrB mutant strain, mainly by decreasing expression levels of outer membrane proteins (OmpC, OmpF, OmpW, OmpA, and OmpX) [15] BaeR: "bacterial adaptive response, response-regulator " [10].