Figure 3.

FRO1 is a functional Fe(III)-chelate reductase when expressed in yeast. Wild-type yeast (DY1457) transformed with the vector or the FRO1-expressing plasmid pYES2.0-FRO1 (FRO1) were grown in iron-replete medium (synthetic dextrose [SD] medium supplemented with 10 μm FeCl₃) (+) or in iron-limiting medium (SD medium supplemented with 1 mm EDTA) (-) and assayed for Fe(III)-chelate reductase activity. Reductase activity values were obtained by first subtracting out reduction occurring in a no-cell background control, so small negative values are possible for strains with no detectable activity.