In this analysis, we show that two rad59 alleles that diminish association of Rad52 with double-strand breaks are synthetically lethal with rad27,

while two others MK0683 order coordinately reduce RAD51-dependent HR and growth, thus linking RAD51-dependent repair with survival. Another allele stimulates HR by stabilizing Rad51-DNA filaments. Therefore, Rad59 influences the repair of replication lesions by HR through its interactions with multiple HR factors. We speculate that the massive increase in replication failure genome-wide that results from loss of Rad27 may be similar to that caused by chemotherapeutic agents in human cells, potentially explaining why the HR apparatus is critical in determining sensitivity to these drugs. Methods Strains All strains used in this study were isogenic and are listed in Additional file 1: Table S1. Standard MX69 chemical structure techniques for yeast strain construction and growth were used [57]. Construction of the rad27::LEU2, rad51::LEU2, rad59::LEU2, rad59-Y92A, rad59-K166A, rad59-K174A, rad59-F180A and srs2::TRP1 alleles have been described previously [27, 58–60]. The rad27::LEU2 allele

can be followed in crosses by PCR, using the forward primer 5′-GCG TTG ACA GCA TAC ATT-3′, and reverse primer 5′-CGT ACA AAC CAA ATG CGG-3′. The rad59::LEU2 allele is followed by PCR using the forward primer 5′-GCC ACA GTT TGG CAA GGG-3′, and the reverse primer 5′-GGG TTT GTT HDAC inhibitor GCC ATC TGC G-3′. The rad59 missense alleles were followed in crosses by allele-specific PCR [27]. Unique forward primers were used to detect rad59-Y92A (5′-GCT AAT GAA ACA TTC GGG GC-3′), rad59-K166A (5′-AAT GTT ATA ACA GGT CGA AAG C-3′), rad59-K174A (5′-AAG GGT TAC GTA GAG GAG AAG-3′), and rad59-F180A (5′-AAG AAG GCG TTA TTG AGC GC-3′). All allele-specific PCRs use the same reverse primer (5′-TAT

ATA AGT ACG TGA GAT CTA TTT G-3′). Presence of the rad59-K174A allele is scored by digesting the PCR product with MseI restriction endonuclease. DNA was purified for PCR analysis using a standard method [61]. Synthetic lethality Diploid yeast strains heterozygous for each of the rad59 alleles (rad59/RAD59) and the rad27::LEU2 Inositol monophosphatase 1 allele (rad27::LEU2/RAD27) were sporulated and dissected. After 72 h, five representative tetrads from each diploid were selected. The presence of rad27 and rad59 mutant alleles in each of the colonies that arose from the spores was scored using PCR as described above. Doubling time At least 10, five-milliliter YPD (1% yeast extract, 2% peptone, 2% dextrose) cultures were inoculated with colonies arising from the spores of freshly dissected tetrads and grown overnight at 30°. These were sub-cultured into Klett tubes containing five milliliters of YPD medium that were incubated at 30° while shaking. Cell density was measured by monitoring culture turbidity with a Klett-Summerson colorimeter each hour over a 10 h period.