Figure 1.

Mutations in ERG genes are synthetically lethal with cdc50Δ mutation. (A) The late steps of the ergosterol biosynthetic pathway. (B) Synthetic lethality between cdc50Δ and erg3. cdc50Δ erg3 mutant harboring pYSLU1-CDC50 (KKT247) was transformed with YCplac111 (vector), YCplac111CDC50 (pCDC50), or pRS315-ERG3 (pERG3). Transformants were streaked onto an SDA + 5-FOA plate and grown at 30°C for 2 d. (C) Genetic interactions between the cdc50Δ and ergΔ mutations. Diploid cells with the indicated genotype were sporulated, dissected, grown at 30°C for 2 d, and photographed. Colonies were replica plated onto selective media to determine the segregation of the marked mutant alleles. Tetrad genotypes (TT, tetratype; PD, parental ditype; and NPD; nonparental ditype) are indicated, and the identities of the double mutant segregants are shown in parentheses. (D) Genetic interactions between the erg3Δ and the drs2Δ, or lem3Δ mutations. Tetrad analysis was performed as in C.