Ufd2 mediates Yap8 stabilization. (A) Yap8 levels are reduced in ufd2 mutant cells compared to the wild type strain. BY4742 wild type (WT) and ufd2 mutant strains expressing Yap8-HA were incubated with 1.5 mM As(III), harvested at the indicated time-points and subjected to immunoblotting using anti-HA and anti-Pgk1 antibodies. The graph represents relative Yap8 levels (AU, Arbitrary Units). (B) Yap8 is destabilized in the ufd2 mutant. The same strains were first exposed to 1.5 mM As(III) for 90 min, washed and subsequently treated with 0.1 mg/ml cycloheximide (CHX) up to 120 min prior to immunoblotting with the antibodies indicated above. The graph represents the percentage of remaining Yap8 protein after CHX addition. Estimated Yap8 half-life is 98 min in the WT strain and 37 min in the ufd2 mutant. (C) Mps1 stability is increased in ufd2 and Ufd2U-boxΔ mutant cells in comparison to WT strain. BY4741 WT, ufd2 and Ufd2U-boxΔ mutant strains carrying the GAL1promoterMPS1-c-myc construct were induced with galactose before being challenged with glucose and 0.1 mg/ml CHX. Cells were harvested at the indicated time-points and subjected to immunoblotting using anti-c-myc and anti-Pgk1 antibodies. The graph represents the percentage of remaining Mps1 protein after CHX addition. A representative experiment is shown. (D) Epistasis analyses of YAP8 and UFD2. Exponential phase BY4742 WT, yap8, ufd2 and yap8ufd2 cells were serially diluted and spotted onto MM media supplemented or not with increasing concentrations of As(V) (up to 2 mM; upper panel) or As(III) (up to 1.5 mM; lower panel). Growth was recorded after 2 days incubation at 30°C. A representative experiment is shown. (E) ACR3 expression is similar in the double yap8ufd2 and single yap8 mutants. The same strains referred in D were challenged with 1.5 mM As(III) for 90 min and ACR3 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<0.05 or ***P<0.001. (F) YAP8 overexpression recovers ufd2 growth in cells exposed to arsenic stress. Exponential phase BY4742 WT and the ufd2 mutant strain overexpressing YAP8 or the vector alone were serially diluted and spotted onto SD media supplemented with 1.5 As(III) or 2 mM As(V). Growth was recorded after 2 days incubation at 30°C. A representative experiment is shown.