Fig. 1.

The Arabidopsis thaliana and Populus trichocarpa MTP11 genes specifically complement the Mn-hypersensitive phenotype of a pmr1Δ yeast mutant. (A) Dilution series of wild-type and mutant yeast strains transformed with PtMTP11.1, PtMTP11.2, AtMTP11, or the empty vector were spotted onto plates supplemented with metals or BAPTA as indicated. (B) Localization in yeast of PtMTP11.1, PtMTP11.2, and AtMTP11 fused to GFP. (C) AtMTP11 mediates ⁵⁴Mn transport. Microsomal vesicles from pmr1Δ yeast transformed with AtMTP11 (filled circles) or the empty vector (open circles) were assayed for ⁵⁴Mn²⁺ uptake activity as described in Materials and Methods. Aliquots (≈100 μg of protein) of the vesicles were preincubated in 500 μl of reaction medium for 5 min at 25°C. MnCl₂ containing ⁵⁴Mn²⁺ was added at 0 min to a total Mn²⁺ concentration of 100 μM. The presented data show net uptake subtracted for background activity in the absence of ATP. The experiment was conducted on three different microsomal preparations with similar results. The means ± SE of four independent samples of one microsomal preparation are shown.