Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use Spo11-oligonucleotide complexes to map the distribution of meiotic DSBs in a spo11 mutant strain of Saccharomyces cerevisiae.
Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use Spo11-oligonucleotide complexes, a byproduct of DSB formation, to map the distribution of meiotic DSBs in pch2 and sir2 mutant strains of Saccharomyces cerevisiae.
Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use S1Seq mapping to map the distribution of meiotic DSBs in spo11 mutant strains of Saccharomyces cerevisiae.
Project description:The nonrandom distribution of meiotic recombination shapes patterns of inheritance and genome evolution, but chromosomal features governing this distribution are poorly understood. Formation of the DNA double-strand breaks (DSBs) that initiate recombination results in accumulation of Spo11 protein covalently bound to small DNA fragments. We show here that sequencing these fragments provides a genome-wide DSB map of unprecedented resolution and sensitivity. We use this map to explore the influence of large-scale chromosome structures, chromatin, transcription factors, and local sequence composition on DSB distributions. Our analysis supports the view that the recombination terrain is molded by combinatorial and hierarchical interaction of factors that work on widely different size scales. Mechanistic aspects of DSB formation and early processing steps are also uncovered. This map illuminates the occurrence of DSBs in repetitive DNA elements, repair of which can lead to chromosomal rearrangements. We discuss implications for evolutionary dynamics of recombination hotspots. We deep sequenced 4 samples of Spo11 oligos on Roche 454 platform. Three samples are technical replicates of Spo11 oligo products prepared from one meiotic culture and the fourth sample was prepared from an independent culture.
Project description: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.
Project description: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. Four samples total: two wild type and two zip3 mutant (each an independent culture)
Project description:The nonrandom distribution of meiotic recombination shapes patterns of inheritance and genome evolution, but chromosomal features governing this distribution are poorly understood. Formation of the DNA double-strand breaks (DSBs) that initiate recombination results in accumulation of Spo11 protein covalently bound to small DNA fragments. We show here that sequencing these fragments provides a genome-wide DSB map of unprecedented resolution and sensitivity. We use this map to explore the influence of large-scale chromosome structures, chromatin, transcription factors, and local sequence composition on DSB distributions. Our analysis supports the view that the recombination terrain is molded by combinatorial and hierarchical interaction of factors that work on widely different size scales. Mechanistic aspects of DSB formation and early processing steps are also uncovered. This map illuminates the occurrence of DSBs in repetitive DNA elements, repair of which can lead to chromosomal rearrangements. We discuss implications for evolutionary dynamics of recombination hotspots.
Project description:Meiotic recombination starts with the formation of DNA double-strand breaks (DSBs) made by Spo11. In Saccharomyces cerevisiae, the nonrandom distribution of meiotic DSBs along the genome can be attributed to the combined influence of multiple factors on Spo11 cleavage. One factor is higher-order chromatin structure, particularly the loop-axis organization of meiotic chromosomes. Axial element proteins Red1 and Hop1 provide the basis for meiotic loop-axis organization and are implicated in diverse aspects of meiotic recombination. Mek1 is a meiotic-specific kinase associated with Red1 and Hop1. Red1, Hop1, and Mek1 are required for normal DSB levels, but their effects on the DSB distribution has not been examined, and exactly how these proteins influence DSB levels and distribution is unknown. Here, we examined the contributions of Red1, Hop1, and Mek1 to the DSB distribution by deep sequencing and mapping Spo11-associated oligonucleotides from red1, hop1, and mek1 mutant strains, thereby generating genome-wide meiotic DSB maps.