Fig. 2. Tryptophan biosynthesis is essential for resistance to a wide range of chemical compounds.

(A) Distribution of phenotype rates for all genes in Yeast Phenome. (B) The biosynthesis of tryptophan and its precursor chorismate are two of the top three biochemical pathways with the highest phenotype rate and the highest phenotypic similarity. Given a list of genes encoding members of a biochemical pathway, we computed the mean and SE (std. err.) of their phenotype rates, as well as the mean and SE for their pairwise phenotypic similarities. Of 187 tested pathways, the 20 pathways with the highest mean phenotype rates are shown. Tryptophan and chorismate biosynthesis are highlighted in red. The number of genes in each pathway is indicated in parentheses. (C) Mutants involved in the biosynthesis of tryptophan (trp1–5) and chorismate (aro1–4), but not other amino acids, share sensitivity to tryptophan-depleted media, low temperature, high pressure, and a wide range of chemical compounds. The heatmap shows NPVs for a set of mutants (columns) in a sample of screens (rows). Mutants (columns) are organized by pathway and include the following: (a) biosynthesis of chorismate and tryptophan, (b) biosynthesis of tyrosine and phenylalanine, (c) the general amino acid control (GAAC) pathway, (d) biosynthesis of arginine, (e) biosynthesis of lysine, and (f) biosynthesis of threonine. Screens (rows) are organized by tested condition and include growth in the following: tryptophan-limited media (Trp⁻); media limited for multiple amino acids, including tryptophan, tyrosine, and phenylalanine (Trp⁻ Tyr⁻ Phe⁻); exposure to low temperature and high pressure (°C/Pa); exposure to haloperidol (Haloperidol); exposure to rotenone and paraquat (ETC/PD); exposure to human hormones (Hormones); and exposure to other chemical compounds (Other).