Genome-wide screens for DNA damage response factors. (a) Arrayed fitness screens. The AID-v2 library was grown on galactose media with or without MMS, CPT, or HU as GAs and 1 μM 5-Ph-IAA. (b) Volcano plots of CGI scores between the AID alleles and the indicated GAs. Negative chemical-genetic interactors with each GA (magenta, colony size [5-Ph-IAA + GA] ≤0.9, CGI score ≤0.2 and P value <0.05 in a two-sided t test, adjusted for multiple testing using the Benjamini-Hochberg method) and RAD52 epistasis group genes (blue) are marked. (c and d) Venn diagram (c) and heatmap (d) of negative chemical-genetic interactors (magenta in b) with the three GAs. d, functional categories based on gene ontology terms (top, Materials and methods) and RAD52 epistasis group genes (bottom) are indicated. (e) Sensitivity of GSF2 mutants to HU. 10-fold serial dilutions of the indicated strains (GSF2-AID* strain from the AID-v2 library, gsf2Δ mutant from the haploid yeast knockout library and an independently constructed gsf2Δ strain) on galactose media with 5-Ph-IAA, HU, or both compounds. (f and g) Flow cytometry analysis of DNA content. Asynchronous cultures grown in galactose medium were treated with HU at time point zero (f). HU-arrested cultures were released into galactose medium without HU (g). G1 and G2 peaks are labeled 1N and 2N, respectively.