Negative supcoils pattern meiotic crossovers
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ABSTRACT:
PROVIDER: PRJNA831113 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR18901200_1.fastq.gz | Fastqsanger.gz | |||
| SRR18901200_2.fastq.gz | Fastqsanger.gz | |||
| SRR18901201_1.fastq.gz | Fastqsanger.gz | |||
| SRR18901201_2.fastq.gz | Fastqsanger.gz | |||
| SRR18901202_1.fastq.gz | Fastqsanger.gz |
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Project description:Interference exists ubiquitously in many biological processes. Crossover interference patterns meiotic crossovers, which are required for faithful chromosome segregation and evolutionary adaption. However, what the interference signal is and how it is generated and regulated are unknown. We show that yeast top2 alleles cannot bind or cleave DNA accumulate a higher level of negative supercoils and show weaker interference. However, top2 alleles cannot religate the cleaved DNA or release the religated DNA accumulate less negative supercoils and show stronger interference. Moreover, the level of negative supercoils is negatively correlated with crossover interference strength in various strains. Furthermore, negative supercoils preferentially enrich at crossover-associated Zip3 regions before the formation of meiotic DNA double-strand breaks, and regions with more negative supercoils tend to have more Zip3. Additionally, the strength of crossover interference and homeostasis change coordinately in mutants. These findings suggest that the accumulation and relief of negative supercoils pattern meiotic crossovers.
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Project description:Crossover recombination is a hallmark of meiosis, which holds the paternal and maternal chromosomes (homologs) together for their faithful separation, meanwhile, it promotes genetic diversity of progenies. The pattern of crossover is mainly controlled by the architecture of meiotic chromosomes. Environmental factors, especially temperature, also play an important role in modulating crossovers. However, it is unclear how temperature affects crossovers. Here, we examined the distributions of budding yeast axis components (Red1, Hop1, and Rec8) and the CO-associated Zip3 foci in detail in different temperatures, and found that both increased and decreased temperatures result in shorter meiotic chromosome axes and more crossovers. Further investigations showed that altered temperature coordinately enhanced the hyperabundant accumulation of Hop1 and Red1 on chromosomes and the number of Zip3 foci. Most importantly, temperature-induced alterations in axis distribution and Zip3 foci depend on the changes in DNA negative supercoil. These findings suggest that yeast meiosis senses temperature changes by increasing the level of negative supercoil to increase crossovers and modulate chromosome organization. These findings provide a novel view in understanding the effect and mechanism of temperature on meiosis recombination and chromosome organization, and thus also have an important implication in evolution and breeding.
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Project description:Negative supercoil senses temperature to modulate meiotic crossovers and chromosomes
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Project description:In most eukaryotes, meiotic crossovers are essential for error-free chromosome segregation but are specifically repressed near centromeres to prevent missegregation. Recognized for >85 years, the molecular mechanism of this repression has remained unknown. Meiotic chromosomes contain two distinct cohesin complexes: pericentric complex (for segregation) and chromosomal arm complex (for crossing-over). We show that the pericentric-specific complex also actively represses pericentric meiotic double-strand break (DSB) formation and, consequently, crossovers. The fission yeast pericentric regions contain heterochromatin, removal of which can result in derepression in double-strand break formation and recombination during meiosis. We uncover the mechanism by which fission yeast heterochromatin protein Swi6 (mammalian HP1-homolog) prevents recruitment of activators of meiotic DSB formation such as Rec10. Localizing these missing activators to wild-type pericentromeres bypasses repression and generates abundant crossovers but reduces gamete viability.The molecular mechanism elucidated here likely extends to other species including humans, where pericentric crossovers can result in disorders such as Down syndrome. These mechanistic insights provide new clues to understand the roles played by multiple cohesin complexes, especially in human infertility and birth defects.
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Project description:Viable gamete formation requires segregation of homologous chromosomes connected, in most species, by crossovers. DNA double-strand break (DSB) formation and the resulting crossovers are regulated at multiple levels to prevent overabundance along chromosomes. Meiotic cells coordinate these events between distant sites, but the physical basis of long-distance chromosomal communication has been unknown. We show that DSB hotspots up to ~200 kb (~35 cM) apart form clusters via hotspot-binding proteins Rec25 and Rec27 in fission yeast. Clustering coincides with hotspot competition and interference over similar distances. Without Tel1 (ATM tumor-suppressor homolog), DSB and crossover interference become negative, reflecting coordinated action along a chromosome. These results indicate that DSB hotspots within a limited chromosomal region and bound by their protein determinants form a clustered structure that, via Tel1, allows only one DSB per region. Such a “roulette” process among clusters explains the observed pattern of crossover interference in fission yeast. Key structural and regulatory components of clusters are phylogenetically conserved, suggesting conservation of this vital regulation. Based on these observations, we discuss variations on a model in which clustering and competition between DSB sites leads to DSB interference and in turn produces crossover interference.
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Project description:Meiotic crossovers result from homology-directed repair of double strand breaks (DSBs). Unlike yeast and plants, where DSBs are generated near gene promoters, in many vertebrates, DSBs are enriched at hotspots determined by the DNA binding activity of the rapidly evolving zinc finger array of PRDM9 (PR domain zinc finger protein 9), which subsequently catalyzes trimethylation of lysine 4 and lysine 36 of Histone H3 in nearby nucleosomes. Here, we identify the dual histone methylation reader ZCWPW1, which is tightly co-expressed during spermatogenesis with Prdm9 and co-evolved with Prdm9 in vertebrates, as an essential meiotic recombination factor required for efficient synapsis and repair of PRDM9-dependent DSBs. In sum, our results indicate that the evolution of dual histone methylation reader/writer system involving Prdm9 and Zcwpw1 facilitated a shift in genetic recombination away from a static pattern near genes towards a flexible pattern controlled by the rapidly evolving DNA binding activity of PRDM9
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