Spo11-oligo mapping in zip3 mutants
Meiotic recombination promotes genetic diversification as well as pairing and segregation of homologous chromosomes, but the double-strand breaks (DSBs) that initiate recombination are dangerous lesions that can cause mutation or meiotic failure. How cells control DSBs to balance between beneficial and deleterious outcomes is not well understood. This study tests the hypothesis that DSB control involves a network of intersecting regulatory circuits. We show that DSBs form in greater numbers in Saccharomyces cerevisiae cells lacking ZMM proteins, a suite of recombination-promoting factors traditionally regarded as acting strictly downstream of DSB formation. This counterintuitive result suggests that homologous chromosomes that have successfully engaged one another stop making DSBs, and provides new insight into phenotypes of zmm and other recombination-defective mutants. A genetically distinct pathway ties DSB formation to meiotic progression through the Ndt80 transcription factor. High-resolution genome-wide DSB maps generated by sequencing short oligonucleotides covalently bound to Spo11 (Spo11 oligos) demonstrate that feedback tied to ZMM function contributes in unexpected ways to spatial patterning of the recombination landscape. Overall design: Four samples total: two wild type and two zip3 mutant (each an independent culture)