FIGURE 2:

The UPR^ER is required for cellular fitness under mitoprotein-induced stress conditions. (A) Wild-type and ∆ire1 cells were grown under non-inducing (left) or inducing (right) conditions, expressing either b₂-DHFR or cytosolic DHFR. ∆ire1 cells are more susceptible to mitoprotein-induced stress. p values denote differences in maximum growth rate, assessed by ANOVA and post hoc testing of pairwise differences (corrected for multiple testing with Benjamini-Hochberg). (B) Tenfold serial dilutions of wild-type, ∆ire1 and ∆hac1 cultures were dropped on lactate plates with or without 0.5% galactose. The UPR^ER-deficient mutants show synthetic growth defects with expression of b₂-DHFR. (C) HAC1 and IRE1 were deleted in temperature-sensitive mia40-4 mutants. Cells were grown in glucose medium and serial dilutions were spotted on glucose plates and incubated at the semipermissive temperature of 30°C. Loss of the UPR^ER results in synthetic growth defects. (D) Early cytonuclear adaptations to mitoprotein-induced stress are accompanied by the induction of the UPR^ER as a second line of defense.