Meiotic recombination and Hop1
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ABSTRACT:
PROVIDER: PRJEB22374 | ENA |
REPOSITORIES: ENA
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Project description:The DNA double strand breaks (DSBs) that initiate meiotic recombination are formed in the context of the meiotic chromosome axis, which in budding yeast contains a meiosis-specific cohesin isoform and the meiosis-specific proteins Hop1 and Red1. Hop1 and Red are important for DSB formation; DSB levels are reduced in their absence and their levels, which vary along the lengths of chromosomes, are positively correlated with DSB levels. How axis protein levels influence DSB formation and recombination remains unclear. To address this question, we developed a novel approach that uses a bacterial ParB-parS partition system to recruit axis proteins at high levels to inserts at recombination coldspots where Hop1 and Red1 levels are normally low. Recruiting Hop1 markedly increased DSBs and homologous recombination at target loci, to levels equivalent to those observed at endogenous recombination hotspots. This local increase in DSBs did not require Red1 or the meiosis-specific cohesin component Rec8, indicating that, of the axis proteins, Hop1 is sufficient to promote DSB formation. However, while most crossovers at endogenous recombination hotspots are formed by the meiosis-specific MutLγ resolvase, only a small fraction of crossovers that formed at an insert locus required MutLγ, regardless of whether or not Hop1 was recruited to that locus. Thus, while local Hop1 levels determine local DSB levels, the recombination pathways that repair these breaks can be determined by other factors, raising the intriguing possibility that different recombination pathways operate in different parts of the genome.
2022-07-12 | GSE201240 | GEO
Project description:The meiotic chromosome axis coordinates chromosome organization and interhomolog recombination in meiotic prophase, and is essential for fertility. In S. cerevisiae, the HORMAD protein Hop1 mediates an enrichment of axis proteins at nucleosome-rich genomic islands through a central chromatin-binding region (CBR). Here, we use cryoelectron microscopy to show that the Hop1 CBR directly recognizes bent nucleosomal DNA through a composite interface in its PHD and winged helix-turn-helix domains. Targeted disruption of the Hop1 CBR-nucleosome interface causes a loss of axis-protein enrichment at nucleosome-rich genomic islands, reduces meiotic DNA double-strand breaks (DSBs), and causes defects in chromosome synapsis. Synthetic effects with the disassemblase Pch2 suggest that nucleosome binding delays a conformational switch in Hop1 from a DSB-promoting, Pch2-inaccessible state to a DSB-inactive, Pch2-accessible state to regulate the extent of meiotic DSB formation . Phylogenetic analyses of meiotic HORMADs reveal an ancient origin of this domain, suggesting that these mechanisms are broadly conserved.
2024-02-28 | GSE225129 | GEO
Project description:Crossovers formed by recombination between homologous chromosomes are important for proper homolog segregation during meiosis and for generation of genetic diversity. Optimal molecular analysis of DNA intermediates of recombination requires synchronous cultures. We previously described a mutant, pat1-as2, of the fission yeast Schizosaccharomyces pombe that undergoes synchronous meiosis at 25°C when an ATP analog is added to the culture. Here, we compare recombination intermediates in pat1-as2 at 25°C with those in the widely used pat1-114 temperature-sensitive mutant at 34°C, a temperature higher than optimal. DNA double-strand breaks at most hotspots are similarly abundant in the two conditions but, remarkably, a few hotspots are distinctly deficient at 25°C. In both conditions Holliday junctions at DNA break hotspots form more frequently between sister chromatids than between homologs, but a novel species, perhaps arising from invasion by only one end of broken DNA, is more readily observed at 25°C. Our results confirm the validity of previous assays of recombination intermediates in S. pombe and provide new information on the mechanism of meiotic recombination.
2013-09-20 | GSE49961 | GEO
Project description:Crossovers formed by recombination between homologous chromosomes are important for proper homolog segregation during meiosis and for generation of genetic diversity. Optimal molecular analysis of DNA intermediates of recombination requires synchronous cultures. We previously described a mutant, pat1-as2, of the fission yeast Schizosaccharomyces pombe that undergoes synchronous meiosis at 25°C when an ATP analog is added to the culture. Here, we compare recombination intermediates in pat1-as2 at 25°C with those in the widely used pat1-114 temperature-sensitive mutant at 34°C, a temperature higher than optimal. DNA double-strand breaks at most hotspots are similarly abundant in the two conditions but, remarkably, a few hotspots are distinctly deficient at 25°C. In both conditions Holliday junctions at DNA break hotspots form more frequently between sister chromatids than between homologs, but a novel species, perhaps arising from invasion by only one end of broken DNA, is more readily observed at 25°C. Our results confirm the validity of previous assays of recombination intermediates in S. pombe and provide new information on the mechanism of meiotic recombination. DNA double-strand break analysis by immunoprecipation of Rec12-FLAG covalently linked to DNA (without exogenous crosslinking agent used) following meiotic induction via pat1-114 or pat1-as2 alleles
2013-09-20 | E-GEOD-49961 | biostudies-arrayexpress
Project description:Homologous recombination events during meiosis cluster at specific loci called hotspots. Hotspot activation requires accessible chromatin, DNA sequence motifs DNA sequence-specific binding proteins, but how these proteins create a suitable environment for Rec12 recruitment is unknown. Here, we purified the ade6-M26 meiotic recombination hotspot from Schizosaccharomyces pombe and identified novel regulators of hotspot activation by mass spectrometry. Small, circular minichromosomes containing the ade6-M26 hotspot or control allele were transformed into strains permitting synchronous meiotic induction and purified from these cultures at sequential time points. Enrichment of known M26 binding factors Atf1 and Pcr1 in the data set validated the approach. Filtering for chromatin-related proteins enriched in the hotspot revealed candidate hotspot regulators, which were validated using genetic studies. This study highlights the power of unbiased proteomic screens to reveal novel insights into fundamental biological processes, and highlights a critical role in H2AZ turnover in mediating access of transcription factors to their underlying DNA-sequence motifs.
2018-11-04 | PXD009649 | Pride
Project description:Meiotic recombination between homologous chromosomes initiates via programmed DNA double-strand breaks (DSBs), generated by complexes comprising Spo11 transesterase plus accessory proteins. DSBs arise concomitantly with the development of axial chromosome structures, where the coalescence of axis sites produces linear arrays of chromatin loops. Recombining DNA sequences map to loops, but are ultimately tethered to the underlying axis. How and when such tethering occurs is currently unclear. Using ChIPchip in yeast, we show that Spo11-accessory proteins Rec114, Mer2 and Mei4 stably interact with chromosome axis sequences, upon phosphorylation of Mer2 by S-phase Cdk. This axis tethering requires meiotic axis components (Red1/Hop1) and is modulated in a domain-specific fashion by cohesin. Loss of Rec114, Mer2 and Mei4 binding correlates with loss of DSBs. Our results strongly suggest that hotspot sequences become tethered to axis sites by the DSB machinery prior to DSB formation.
2011-08-28 | GSE29860 | GEO
Project description:Meiotic chromosomes are highly compacted yet remain transcriptionally active. To understand how chromosome folding accommodates transcription, we investigated the assembly of the axial element, the proteinaceous structure that compacts meiotic chromosomes and promotes recombination and fertility. We found that the axial element proteins of budding yeast are flexibly anchored to chromatin by the ring-like cohesin complex and biased towards small chromosomes by a separate modulating mechanism that requires the conserved axial-element component Hop1. The ubiquitous presence of cohesin at sites of convergent transcription provides well-dispersed points for axis attachment and thus compaction. Axis protein enrichment at these sites directly correlates with the propensity for recombination initiation. Importantly, axis anchoring by cohesin is adjustable and readily displaced in the direction of transcription by the transcriptional machinery. We propose that such robust but flexible tethering allows the axial element to promote recombination while easily adapting to changes in chromosome activity. 7 genome wide meiotic ChIP-seq sets: V5-Red1 DNA interaction (V5-Red1-ChIP), V5-Red1 DNA interaction in the absence of axis protein Hop1 (V5-Red1-ChIP, hop1delta), V5-Red1 DNA interaction in the absence of another two axis proteins Hop1 and Rec8 (V5-Red1-ChIP, hop1delta rec8delta), Rec8-HA DNA interaction (Rec8-HA-ChIP), Rec8-HA DNA interactionin the absence of Red1 (Rec8-HA-ChIP, red1delta), and 2 untagged control (V5-untagged-ChIP, HA-untagged-ChIP) (corresponding to the main Figure5)
2015-08-07 | E-GEOD-70112 | biostudies-arrayexpress
Project description:Meiotic chromosomes are highly compacted yet remain transcriptionally active. To understand how chromosome folding accommodates transcription, we investigated the assembly of the axial element, the proteinaceous structure that compacts meiotic chromosomes and promotes recombination and fertility. We found that the axial-element proteins of budding yeast are flexibly anchored to chromatin by the ring-like cohesin complex and biased towards small chromosomes by a separate modulating mechanism that requires the conserved axial element component Hop1. The ubiquitous presence of cohesin at sites of convergent transcription provides well-dispersed points for axis attachment and thus compaction. Axis protein enrichment at these sites directly correlates with the propensity for recombination initiation nearby. Importantly, axis anchoring by cohesin is adjustable and readily displaced in the direction of transcription by the transcriptional machinery. We propose that such robust but flexible tethering allows the highly structured axial element to promote recombination while easily adapting to changes in chromosome activity. ChIP-seq experiments were undertaken to understand the features of meiotic chromosomal axes assembly in meiosis. The genome-wide distribution of axis proteins including Hop1, Red1 as well as cohesin subunits Rec8 and Smc3 were measured. Axis protein binding pattern is also measured in rec8 mutant and pREC8-SCC1 in rec8 mutant.
2015-08-06 | E-GEOD-69231 | biostudies-arrayexpress
Project description:Recombination-mediated linking of homologous chromosomes is a unique meiotic feature that enables the halving of chromosomal ploidy in sexual life cycles. Meiotic recombination is initiated by programmed DNA double-strand breaks (DSBs) that are generated by focal multi-protein clusters that condense onto chromosomal axes by poorly understood mechanisms. We discovered in mice that a DBF4-dependent kinase (DDK)–modulated interaction between IHO1 and the chromosomal axis component HORMAD1 effects the formation of axis-bound IHO1 platforms that enhance nucleation of cytologically distinguishable DSB-machinery clusters. This IHO1-HORMAD1-mediated seeding of the DSB-machinery ensures that sufficient DSBs form for efficient pairing of homologous chromosomes. In the absence of IHO1-HORMAD1 interaction, residual DSB activity depends on ANKRD31, which enhances both the seeding and the growth of DSB-machinery clusters. Thus, meiotic DSBs are ensured by complementing pathways that differentially effect seeding and growth of DSB-machinery clusters, and that synergistically enable assembly of the DSB machinery on chromosomal axes.
2024-02-23 | PXD042221 | Pride
Project description:Recombination-mediated linking of homologous chromosomes is a unique meiotic feature that enables the halving of chromosomal ploidy in sexual life cycles. Meiotic recombination is initiated by programmed DNA double-strand breaks (DSBs) that are generated by focal multi-protein clusters that condense onto chromosomal axes by poorly understood mechanisms. We discovered in mice that a DBF4-dependent kinase (DDK)–modulated interaction between IHO1 and the chromosomal axis component HORMAD1 effects the formation of axis-bound IHO1 platforms that enhance nucleation of cytologically distinguishable DSB-machinery clusters. This IHO1-HORMAD1-mediated seeding of the DSB-machinery ensures that sufficient DSBs form for efficient pairing of homologous chromosomes. In the absence of IHO1-HORMAD1 interaction, residual DSB activity depends on ANKRD31, which enhances both the seeding and the growth of DSB-machinery clusters. Thus, meiotic DSBs are ensured by complementing pathways that differentially effect seeding and growth of DSB-machinery clusters, and that synergistically enable assembly of the DSB machinery on chromosomal axes.
2024-02-23 | PXD042179 | Pride