Fig. 3.

Ufd2 mediates arsenic tolerance. (A) ufd2 cells are sensitive to arsenic stress. Exponential phase BY4742 wild type (WT) and the ufd2 mutant were serially diluted and spotted onto SC media supplemented or not with 1.5 mM As(III) or 2 mM As(V) or 1.5 mM As(III). SD, control. Growth was recorded after 2 days incubation at 30°C. A representative experiment is shown. Cell growth was also monitored by means of growth curves. Exponential phase BY4742 WT and ufd2 mutant cells were exposed or not to 2 mM As(V) or 1.5 mM As(III) for 22 h and OD₆₀₀ was monitored in intervals of 1 h. The curves represent the mean±s.d. of three biological replicates. (B) UFD2 is induced in cells injured with arsenic. BY4742 cells were challenged or not with 1.5 mM As(III) or 2 mM As(V) or 1.5 mM As(III) and UFD2 mRNA levels were determined by qRT-PCR (AU, Arbitrary Units). Values represent the mean±s.d. of three biological replicates and statistical differences denoted as ***P<0.001. (C) Ufd2 protein levels increase during arsenic stress. BY4742 cells expressing Ufd2-HA were treated with 2 mM As(V) or 1.5 mM As(III) and harvested at the indicated time-points. SD, control. Immunoblottings were performed using anti-HA and anti-Pgk1 antibodies. Pgk1 was used as loading control. The graphs represent relative Ufd2 levels (AU, Arbitrary Units). Representative experiments are shown.