Abstract
An essential feature of meiosis is Spo11 catalysis of programmed DNA double strand breaks (DSBs). Evidence suggests that the number of DSBs generated per meiosis is genetically determined and that this ability to maintain a pre-determined DSB level, or “DSB homeostasis”, might be a property of the meiotic program. Here, we present direct evidence that Rec114, an evolutionarily conserved essential component of the meiotic DSB-machinery, interacts with DSB hotspot DNA, and that Tel1 and Mec1, the budding yeast ATM and ATR, respectively, down-regulate Rec114 upon meiotic DSB formation through phosphorylation. Mimicking constitutive phosphorylation reduces the interaction between Rec114 and DSB hotspot DNA, resulting in a reduction and/or delay in DSB formation. Conversely, a non-phosphorylatable rec114 allele confers a genome-wide increase in both DSB levels and in the interaction between Rec114 and the DSB hotspot DNA. These observations strongly suggest that Tel1 and/or Mec1 phosphorylation of Rec114 following Spo11 catalysis down-regulates DSB formation by limiting the interaction between Rec114 and DSB hotspots. We also present evidence that Ndt80, a meiosis specific transcription factor, contributes to Rec114 degradation, consistent with its requirement for complete cessation of DSB formation. Loss of Rec114 foci from chromatin is associated with homolog synapsis but independent of Ndt80 or Tel1/Mec1 phosphorylation. Taken together, we present evidence for three independent ways of regulating Rec114 activity, which likely contribute to meiotic DSBs-homeostasis in maintaining genetically determined levels of breaks.
Highlights
In most sexually reproducing organisms, meiotic recombination is initiated by programmed catalysis of DNA double strand breaks (DSBs) by Spo11, an evolutionarily conserved type II topoisomerase-like transesterase [1]
Meiotic DSBs are essential for meiosis; each break represents a potentially lethal or mutagenic DNA lesion that must be repaired before the first meiotic division (MI)
An essential feature of meiosis is meiotic recombination, during which the programmed generation of DNA double-strand-breaks (DSBs) is followed by the production of crossover(s) between two parental homologs, which facilitates their correct distribution to daughter nuclei
Summary
In most sexually reproducing organisms, meiotic recombination is initiated by programmed catalysis of DNA double strand breaks (DSBs) by Spo, an evolutionarily conserved type II topoisomerase-like transesterase [1]. In Saccharomyces cerevisiae, where the process is best understood, Spo activity requires nine additional proteins, five of which are meiosis specific (Rec102, Rec104, Rec114, Mei, and Mer2), and four that are expressed during both meiosis and vegetative growth (Rad, Mre, Xrs, and Ski8) [2]. These proteins interact with each other and/or with Spo to form a complex referred to as the Spo11- or DSBcomplex, or DSB-machinery, and participate in the Spo transesterase reaction that leads to the formation of a DSB (reviewed in [2]). The number of breaks catalyzed per meiosis is developmentally programmed; in yeast or mammals, the number is approximately 150–250 per meiosis, whereas in Drosophila, it is about 25 [6,7,8,9,10]
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