Meiotic DNA double strand breaks in the yeast Saccaromyces cerevisiae

ABSTRACT: DNA double-strand breaks (DSBs) initiate meiotic recombination. Past DSB-mapping studies have used rad50S or sae2? mutants, which are defective in break processing, to accumulate DSBs, and report large (= 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2? mutants. We therefore developed novel methods that detect DSBs using ssDNA enrichment and microarray hybridization, and that use background-based normalization to allow cross-comparison between array datasets, to map genome-wide the DSBs that accumulate in processing-capable, repair-defective dmc1î and dmc1î rad51î mutants. DSBs were observed at known hotspots, but also in most previously-identified “DSB-cold” regions, including near centromeres and telomeres. While about 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1? shows that most of these regions have significant DSB activity. Thus, DSBs are distributed much more uniformly than was previously believed. Southern-blot assays of DSBs in selected regions in dmc1?, rad50S and wild-type cells confirm these findings. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as the primary strand transfer activity genome-wide, and Spo11-induced lesions as initiating all meiotic recombination. Keywords: DSB mapping, ChIP-chip, single strand DNA , BND cellulose

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE8981 | GEO | 2007/12/31

SECONDARY ACCESSION(S): PRJNA102441

REPOSITORIES: GEO