Spo11-oligo mapping in bas1 and ino4 mutants

Meiotic recombination is initiated by developmentally programmed DNA double-strand breaks (DSBs). In S. cerevisiae, the vast majority of DSBs occur in the nucleosome-depleted regions at gene promoters, where transcription factors (TFs) bind. It has been proposed that TF binding can stimulate DSB formation nearby by modulating local chromatin structure. However, a prior study in TF bas1 mutant suggested that the role of TF binding in determining break formation is complex. Here, we examined fine-scale DSB distributions in TF mutant (bas1Δ and ino4Δ) strains. In bas1Δ mutants, 239 out of the 2468 hotspots showed reduced DSB activity, whereas 87 hotspots showed increased DSB activity. Similarly, in ino4Δ mutant, 415 out of the 2468 hotspots showed reduced DSB activity, whereas 322 hotspots showed increased DSB activity. We also mapped Bas1 and Ino4 binding sites in meiosis and found that only a small portion of the affected hotspots contained TF binding sites. This indicates that TF can influence DSB distribution both directly and indirectly. Surprisingly, these DSB changes in TF mutants did not correlate with change in chromatin structure and histone H3K4me3 modification, suggesting that the role of TF on DSB distribution cannot be simply explained by affecting local chromatin status. Nine samples total: two wild type, four bas1 mutant and three ino4 mutant (each an independent culture)