The E. coli BaeSR two-component regulatory system

Abstract

The Escherichia coli genome is filled with genes encoding members of the multidrug transporter family. Characterizing this family of transporters is crucial to combating multidrug resistance, which is an increasingly alarming consequence of antibiotic treatment of infectious disease. Baranova and Nikaido [ 1. Baranova N. Nikaido H. The baeSR two-component regulatory system activates transcription of the yegMNOB (mdtABCD) transporter gene cluster in Escherichia coli and increases its resistance to novobiocin and deoxycholate. J. Bacteriol. 2002; 184: 4168-4176 Crossref PubMed Scopus (188) Google Scholar ] searched an inducible chromosomal library for increased multidrug resistance and found that induction of the gene baeR conferred resistance to novobiocin and deoxycholate. Nagakubo et al. [ 2. Nagakubo S. et al. The putative response regulator BaeR stimulates multidrug resistance of Escherichia coli via a novel multidrug exporter system, MdtABC. J. Bacteriol. 2002; 184: 4161-4167 Crossref PubMed Scopus (198) Google Scholar ] simultaneously published the results of their search for multidrug resistance genes in E. coli, which yielded mdtABCD and baeSR in neighboring loci. Both studies had to be done in an AcrAB-deficient strain as the well-characterized AcrAB efflux pump masks antibiotic resistance detection in wild-type strains. BaeSR is a previously identified two-component regulatory system whose targets were unknown. Both groups agree that BaeR activates the transcription of the mdt locus.