FIG 2.

brl1 mutants have defects in sterol homeostasis. (A) Hypersensitivity of brl1 mutant cells to inhibitors of sterol biosynthesis. Serial dilutions of wild-type, brl1, and brr6 strains were spotted onto SC plates containing the indicated concentration of fenpropimorph (Fen), terbinafine (Terb), or fluconazole (Flu), and plates were incubated at 30°C. (B) brl1 cells accumulate lipid droplets (LDs) and have aberrant LD morphology. Cells of the indicated genotypes were grown in SC medium, and LDs were stained with BODIPY 493/503. Colocalization with the ER marker Kar2-mRFP-HDEL reveals perinuclear clustering of LDs in brl1 cells. The average number of LDs ± the standard deviation of the mean (n, 100 cells) is given for each genotype. Bar, 5 μm. (C) brl1 mutants are synthetically lethal with mutants that fail to synthesize TAG (dga1Δ lro1Δ mutants) or STE (are1Δ are2Δ mutants). brl1 mutant cells rescued by a plasmid-borne wild-type copy of BRL1 (URA3) were deleted for the indicated neutral-lipid biosynthetic gene, and loss of the wild-type copy of BRL1 was assessed on plates containing 5-fluoroorotic acid (5-FOA).