FIG. 4.

Expression of lmrC, lmrD, and lmrR in L. lactis MG1363 and MDR strains and binding of Hoechst 33342 to LmrR. (A to C) The expression of lmrC, lmrD, lmrR, and the control gene secY was measured by RT-PCR using specific primer pairs and total RNA isolated from the parental L. lactis MG1363 incubated in the presence of Hoechst 33342 (5 μM) (A) or daunomycin (50 μM) (B) and from the drug-resistant Dau^r, Eth^r, and Rho^r derivatives in the absence of drugs (C). WT, wild type. (D) Binding of Hoechst 33342 to LmrR (○) and the LmrR(T82I) mutant (•). Binding was measured as an increase in Hoechst 33342 fluorescence (a.u., arbitrary units).