The Double-Strand Break Landscape of Meiotic Chromosomes Is Shaped by the Paf1 Transcription Elongation Complex in Saccharomyces cerevisiae

Genomic features of DSB re-landscaping in rtf1 mutants. Histone modification is a critical determinant of frequency and location of double-strand breaks (DSBs), which induce recombination during meiosis. The Set1-dependent histone H3K4 and Dot1-dependent H3K79 methylations play an important role in DSB formations in budding yeast. Both methylations are promoted by the RNA polymerase II associated factor 1 (Paf1) complex, Paf1C. This study addressed a role of the Paf1C component Rtf1, which is critical for H3K4 and H3K79 methylations, for the regulation of meiotic DSB formation. Similar to set1 mutation, rtf1 mutation decreased the occurrence of DSBs in the genome. The rtf1 set1 double mutant exhibited a larger reduction in the levels of DSBs than the frequency of DSBs detected in either of the single mutants; this indicates independent roles of Rtf1 and Set1 in DSB formation. Importantly, the distribution of DSBs along chromosomes in the rtf1 mutant changed in a different manner than the pattern observed in the set1 and set1 dot1 mutants; this was characterized by enhanced DSB formation at some DSB-cold regions. These observations suggest that Rtf1, and, possibly, the Paf1C, determine DSB landscape in the genome, independent of H3K4 methylation. dmc1(WT) and rtf1dmc1 mutants cells were harvested during a synchronous meiotic time course at 0 and 5 hours. Isolated ssDNA was differentially labled for each time point and hybridized to a high density microarray. This experiment was repeated with biological replicates and a dye swap.