The MfsM2 efflux transporter controls MDR2.
(A) Bitertanol (14C-labeled) accumulation after 10 min (shaded) and 60 min (white bars). Significant differences of values (10 min) of the mutants to those of their MDR2 parent strains are indicated: ** p<0.01. (B) Drug sensitivities. Mean values of resistance factors relative to B05.10 are shown, from two MDR2 strains (D06.2-6, D06.6-5; white bars), strains D06.2-6(ΔmfsM2) and D06.6-5(ΔmfsM2) (black bars), and from two transformants of strain B05.Hyg-3(mfsM2ox) (grey bars). Significant differences of corresponding values are indicated between MDR2 (ΔmfsM2) mutants and their parent strains, and between strain B05.Hyg-3(mfsM2ox) and strain B05.Hyg-3: n.s.: Not significant; * p<0.05; ** p<0.01; *** p<0.001. §Due to limited solubility of tolnaftate, no accurate values above 25-fold could be determined. Drugs (abbreviated) are listed in the same order as in Table 1, except for the omission of carbendazim. (C) Drug sensitivity phenotypes on HA plates. 1: D06.2-6(MDR2); 2: D06.2-6(ΔmfsM2); 3: B05.10 (sensitive); 4: B05.Hyg-3(mfsM2ox)-4, 5: D06.6-5(MDR2); 6: D06.6-5(ΔmfsM2); 7: B05.Hyg-3 (sensitive); 8: B05.Hyg-3(mfsM2ox)-11. Strains with mfsM2 mutations showed a slight growth difference to their parent strains. Pictures were taken 3 d.p.i., except for bitertanol (4 d.p.i.). Concentrations of drugs were adjusted to reveal clear differences between the strains which overexpress mfsM2 and those which do not.