MarA-like regulator of multidrug resistance in Yersinia pestis

Abstract

MarA47(Yp) from Yersinia pestis, showing 47% identity to Escherichia coli MarA in its N terminus, caused resistance to antibiotics and to organic solvents when expressed in both E. coli and Y. pestis. Resistance was linked to increased expression of the AcrAB multidrug efflux pump. In four of five spontaneous multidrug-resistant mutants of Y. pestis independently selected by growth on tetracycline, the marA47(Yp) gene was overexpressed. The findings suggest that marA47(Yp) is a marA ortholog in Y. pestis.

FIG. 1.

Alignment of MarA47_Yp with MarA and other members of the AraC family. The ClustalW program was used for the alignment of MarA47_Yp with other members of AraC family. The shaded and open horizontal boxes represent the helix-turn-helix (HTH) motifs of MarA. The gray shaded residues are the hydrophobic core of the HTH motif, and the black shaded residues determine the sequence specificity. Asterisks mark the residues that interact with the phosphate backbone group of DNA as determined from the structure of E. coli MarA (23). EMarA, E. coli MarA; YPMarA47, Y. pestis ortholog of MarA; RamA, MarA ortholog from Klebsiella pneumoniae; ESoxS, E. coli SoxS; ERob, E. coli Rob; PqrA, MarA ortholog from Proteus vulgaris; EAraC, E. coli AraC.

FIG. 2.

AcrA expression in multidrug-resistant mutants of Y. pestis. AcrA expression was determined by Western blot assay using anti-AcrA antibodies (see Materials and Methods). E. coli AG100A deleted of acrAB and E. coli AG100B deleted of acrR (overexpressing AcrAB) served as negative and positive controls, respectively.