FIGURE 4: Genome-wide fitness assay. (A) Determination of IC-50 for drimenol (1) activity against C. albicans and S. cerevisiae. Yeast growth conditions (YPD medium at 30°C) were used to determine the IC-50 values. The red line in each panel indicates growth of the DMSO reference. An IC-50 of ∼25 μg/ml for C. albicans and ∼15 μg/ml for S. cerevisiae was calculated for 1. Albicanol (2) showed weaker activity against both fungi and was not considered for further analysis. (B, C) Genome-wide screens of S. serevisiae (B) and C. albicans (C) mutant libraries against drimenol (1) for drug induced hypersensitivity. Pooled collections of S. cerevisiae nonessential homozygous and essential heterozygous mutants were grown in the presence and absence of 1 at the concentration of 0.025 mg/ml for the indicated number of generations before profiling for their abundance (DNA barcodes). 20 generations for essential heterozygous and five generations for non-essential homozygous mutants were used. Similarly, C. albicans Tn-insertion mutants (heterozygous, 20 generations) were treated with 0.025 mg/ml of 1. Each spot represents a single mutant. The log ratio of each mutant (1 exposed vs no drug control) was calculated and presented in scatter plots where greater the number the more sensitive that strain is to the treatment.