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Scott Keeney - One of the best experts on this subject based on the ideXlab platform.
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DNA-driven condensation assembles the meiotic DNA break machinery
Nature, 2021Co-Authors: Corentin Claeys Bouuaert, Juncheng Wang, Cédric Oger, Dima Daccache, Wei Xie, Dinshaw J. Patel, Scott KeeneyAbstract:The accurate segregation of chromosomes during meiosis—which is critical for genome stability across sexual cycles—relies on homologous recombination initiated by DNA double-strand breaks (DSBs) made by the Spo11 Protein^ 1 , 2 . The formation of DSBs is regulated and tied to the elaboration of large-scale chromosome structures^ 3 – 5 , but the Protein assemblies that execute and control DNA breakage are poorly understood. Here we address this through the molecular characterization of Saccharomyces cerevisiae RMM (Rec114, Mei4 and Mer2) Proteins—essential, conserved components of the DSB machinery^ 2 . Each subcomplex of Rec114–Mei4 (a 2:1 heterotrimer) or Mer2 (a coiled-coil-containing homotetramer) is monodispersed in solution, but they independently condense with DNA into reversible nucleoProtein clusters that share properties with phase-separated systems. Multivalent interactions drive this condensation. Mutations that weaken Protein–DNA interactions strongly disrupt both condensate formation and DSBs in vivo, and thus these processes are highly correlated. In vitro, condensates fuse into mixed RMM clusters that further recruit Spo11 complexes. Our data show how the DSB machinery self-assembles on chromosome axes to create centres of DSB activity. We propose that multilayered control of Spo11 arises from the recruitment of regulatory components and modulation of the biophysical properties of the condensates. During meiosis, Mer2 and the Rec114–Mei4 complex form condensates that facilitate the formation of double-strand DNA breaks by recruiting the Spo11 transesterase complex.
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Concerted cutting by Spo11 illuminates DNA break mechanisms and initiates gap repair during meiosis
2020Co-Authors: Dominic Johnson, Scott Keeney, Margaret Crawford, Tim Cooper, Corentin Claeys Bouuaert, Bertrand Llorente, Valerie Garcia, Matthew NealeAbstract:Genetic variation arises during meiosis via repair of DNA double-strand breaks (DSBs) created by the topoisomerase-like Spo11 Protein. These DSBs are thought to always occur sparsely across the genome, with isolated DSBs generating discrete recombination events. We challenge this view, demonstrating that hyper-localised coincident DSBs frequently form within hotspots in both S. cerevisiae and mouse—a process suppressed by the DNA damage response kinase Tel1/ATM. Remarkably, the distances separating coincident DSBs vary with ~10.5 bp periodicity, invoking a model where adjacent Spo11 molecules have a fixed orientation relative to the DNA helix. Deep sequencing of meiotic progeny identifies recombination scars consistent with gap repair initiated by adjacent DSBs. Our results revise current thinking about how genetic recombination initiates, reviving original concepts of meiotic recombination as double-strand gap repair.
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Mechanism and regulation of meiotic recombination initiation
Cold Spring Harbor Perspectives in Biology, 2015Co-Authors: Isabel Lam, Scott KeeneyAbstract:Meiotic recombination involves the formation and repair of programmed DNA double-strand breaks (DSBs) catalyzed by the conserved Spo11 Protein. This review summarizes recent studies pertaining to the formation of meiotic DSBs, including the mechanism of DNA cleavage by Spo11, Proteins required for break formation, and mechanisms that control the location, timing, and number of DSBs. Where appropriate, findings in different organisms are discussed to highlight evolutionary conservation or divergence.
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Spo11 and the formation of DNA double-strand breaks in meiosis
Genome Dynamics and Stability, 2008Co-Authors: Scott KeeneyAbstract:Meiotic recombination is carried out through a specialized pathway for the formation and repair of DNA double-strand breaks made by the Spo11 Protein, a relative of archaeal topoisomerase VI. This review summarizes recent studies that provide insight to the mechanism of DNA cleavage by Spo11, functional interactions of Spo11 with other Proteins required for break formation, mechanisms that control the timing of recombination initiation, and evolutionary conservation and divergence of these processes.
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crossover homeostasis in yeast meiosis
Cell, 2006Co-Authors: Emmanuelle Martini, Robert L Diaz, Neil Hunter, Scott KeeneyAbstract:Crossovers produced by homologous recombination promote accurate chromosome segregation in meiosis and are controlled such that at least one forms per chromosome pair and multiple crossovers are widely spaced. Recombination initiates with an excess number of double-strand breaks made by Spo11 Protein. Thus, crossover control involves a decision by which some breaks give crossovers while others follow a predominantly noncrossover pathway(s). To understand this decision, we examined recombination when breaks are reduced in yeast Spo11 hypomorphs. We find that crossover levels tend to be maintained at the expense of noncrossovers and that genomic loci differ in expression of this "crossover homeostasis." These findings define a previously unsuspected manifestation of crossover control, i.e., that the crossover/noncrossover ratio can change to maintain crossovers. Our results distinguish between existing models of crossover control and support the hypothesis that an obligate crossover is a genetically programmed event tied to crossover interference.
M J Neale - One of the best experts on this subject based on the ideXlab platform.
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Initiation of meiotic recombination by formation of DNA double-strand breaks: mechanism and regulation.
Biochemical Society transactions, 2006Co-Authors: Scott Keeney, M J NealeAbstract:Homologous recombination is essential for accurate chromosome segregation during meiosis in most sexual organisms. Meiotic recombination is initiated by the formation of DSBs (DNA double-strand breaks) made by the Spo11 Protein. We review here recent findings pertaining to Protein-Protein interactions important for DSB formation, the mechanism of an early step in the processing of Spo11-generated DSBs, and regulation of DSB formation by Protein kinases.
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Endonucleolytic processing of covalent Protein-linked DNA double-strand breaks
Nature, 2005Co-Authors: M J Neale, Jing Pan, Scott KeeneyAbstract:DNA double-strand breaks (DSBs) with Protein covalently attached to 5′ strand termini are formed by Spo11 to initiate meiotic recombination. The Spo11 Protein must be removed for the DSB to be repaired, but the mechanism for removal is unclear. Here we show that meiotic DSBs in budding yeast are processed by endonucleolytic cleavage that releases Spo11 attached to an oligonucleotide with a free 3′-OH. Two discrete Spo11-oligonucleotide complexes were found in equal amounts, differing with respect to the length of the bound DNA. We propose that these forms arise from different spacings of strand cleavages flanking the DSB, with every DSB processed asymmetrically. Thus, the ends of a single DSB may be biochemically distinct at or before the initial processing step-much earlier than previously thought. Spo11-oligonucleotide complexes were identified in extracts of mouse testis, indicating that this mechanism is evolutionarily conserved. Oligonucleotide- topoisomerase II complexes were also present in extracts of vegetative yeast, although not subject to the same genetic control as for generating Spo11-oligonucleotide complexes. Our findings suggest a general mechanism for repair of Protein-linked DSBs.
Richard J. Bennett - One of the best experts on this subject based on the ideXlab platform.
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The Parasexual Cycle in Candida albicans Provides an Alternative Pathway to Meiosis for the Formation of Recombinant Strains
2013Co-Authors: Anja Forche, Dana Schaefer, Judith Berman, Kevin Alby, Er D. Johnson, Richard J. BennettAbstract:Candida albicans has an elaborate, yet efficient, mating system that promotes conjugation between diploid a and a strains. The product of mating is a tetraploid a/a cell that must undergo a reductional division to return to the diploid state. Despite the presence of several ‘‘meiosis-specific’ ’ genes in the C. albicans genome, a meiotic program has not been observed. Instead, tetraploid products of mating can be induced to undergo efficient, random chromosome loss, often producing strains that are diploid, or close to diploid, in ploidy. Using SNP and comparative genome hybridization arrays we have now analyzed the genotypes of products from the C. albicans parasexual cycle. We show that the parasexual cycle generates progeny strains with shuffled combinations of the eight C. albicans chromosomes. In addition, several isolates had undergone extensive genetic recombination between homologous chromosomes, including multiple gene conversion events. Progeny strains exhibited altered colony morphologies on laboratory media, demonstrating that the parasexual cycle generates phenotypic variants of C. albicans. In several fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, the conserved Spo11 Protein is integral to meiotic recombination, where it is required for the formation of DNA double-strand breaks. We show that deletion of Spo11 prevented genetic recombination between homologous chromosomes during the C. albicans parasexual cycle. These findings suggest that at least one meiosis-specific gene has been re-programmed to mediate genetic recombination during the alternative parasexual life cycle of C. albicans. We discuss, in light of the long association of C. albicans wit
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The parasexual cycle in Candida albicans provides an alternative pathway to meiosis for the formation of recombinant strains
PLoS Biology, 2008Co-Authors: Anja Forche, Dana Schaefer, Judith Berman, Kevin Alby, Alexander D Johnson, Richard J. BennettAbstract:Candida albicans has an elaborate, yet efficient, mating system that promotes conjugation between diploid a and alpha strains. The product of mating is a tetraploid a/alpha cell that must undergo a reductional division to return to the diploid state. Despite the presence of several "meiosis-specific" genes in the C. albicans genome, a meiotic program has not been observed. Instead, tetraploid products of mating can be induced to undergo efficient, random chromosome loss, often producing strains that are diploid, or close to diploid, in ploidy. Using SNP and comparative genome hybridization arrays we have now analyzed the genotypes of products from the C. albicans parasexual cycle. We show that the parasexual cycle generates progeny strains with shuffled combinations of the eight C. albicans chromosomes. In addition, several isolates had undergone extensive genetic recombination between homologous chromosomes, including multiple gene conversion events. Progeny strains exhibited altered colony morphologies on laboratory media, demonstrating that the parasexual cycle generates phenotypic variants of C. albicans. In several fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, the conserved Spo11 Protein is integral to meiotic recombination, where it is required for the formation of DNA double-strand breaks. We show that deletion of Spo11 prevented genetic recombination between homologous chromosomes during the C. albicans parasexual cycle. These findings suggest that at least one meiosis-specific gene has been re-programmed to mediate genetic recombination during the alternative parasexual life cycle of C. albicans. We discuss, in light of the long association of C. albicans with warm-blooded animals, the potential advantages of a parasexual cycle over a conventional sexual cycle.
Bernard Massy - One of the best experts on this subject based on the ideXlab platform.
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programmed induction of dna double strand breaks during meiosis setting up communication between dna and the chromosome structure
Current Opinion in Genetics & Development, 2013Co-Authors: Valerie Borde, Bernard MassyAbstract:During the first meiotic prophase, hundreds of DNA double strand breaks (DSBs) are deliberately self-inflicted along chromosomes in order to promote homologous recombination between homologs. These DSBs, catalyzed by the evolutionary conserved Spo11 Protein, are highly regulated. Recent studies in yeast and mammals have identified key components involved in meiotic DSB formation. In mammals, the DNA binding specificity of PRDM9 determines where DSB occur, whereas in yeast, Spo11 acts in regions which one important feature is chromatin accessibility. However, DSB formation requires additional Proteins located on chromosome axes, and the Saccharomyces cerevisiae Protein, Spp1 has been recently identified to make the link between axes and DSB sites. These recent findings open exciting routes to understanding how the requirement to regulate DSBs along and between homologs is achieved.
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Initiation of Meiotic Recombination: How and Where? Conservation and Specificities Among Eukaryotes
Annual Review of Genetics, 2013Co-Authors: Bernard MassyAbstract:Meiotic recombination is essential for fertility in most sexually reproducing species. This process also creates new combinations of alleles and has important consequences for genome evolution. Meiotic recombination is initiated by the formation of DNA double-strand breaks (DSBs), which are repaired by homologous recombination. DSBs are catalyzed by the evolutionarily conserved Spo11 Protein, assisted by several other factors. Some of them are absolutely required, whereas others are needed only for full levels of DSB formation and may participate in the regulation of DSB timing and frequency as well as the coordination between DSB formation and repair. The sites where DSBs occur are not randomly distributed in the genome, and remarkably distinct strategies have emerged to control their localization in different species. Here, I review the recent advances in the components required for DSB formation and localization in the various model organisms in which these studies have been performed.
Anja Forche - One of the best experts on this subject based on the ideXlab platform.
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The Parasexual Cycle in Candida albicans Provides an Alternative Pathway to Meiosis for the Formation of Recombinant Strains
2013Co-Authors: Anja Forche, Dana Schaefer, Judith Berman, Kevin Alby, Er D. Johnson, Richard J. BennettAbstract:Candida albicans has an elaborate, yet efficient, mating system that promotes conjugation between diploid a and a strains. The product of mating is a tetraploid a/a cell that must undergo a reductional division to return to the diploid state. Despite the presence of several ‘‘meiosis-specific’ ’ genes in the C. albicans genome, a meiotic program has not been observed. Instead, tetraploid products of mating can be induced to undergo efficient, random chromosome loss, often producing strains that are diploid, or close to diploid, in ploidy. Using SNP and comparative genome hybridization arrays we have now analyzed the genotypes of products from the C. albicans parasexual cycle. We show that the parasexual cycle generates progeny strains with shuffled combinations of the eight C. albicans chromosomes. In addition, several isolates had undergone extensive genetic recombination between homologous chromosomes, including multiple gene conversion events. Progeny strains exhibited altered colony morphologies on laboratory media, demonstrating that the parasexual cycle generates phenotypic variants of C. albicans. In several fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, the conserved Spo11 Protein is integral to meiotic recombination, where it is required for the formation of DNA double-strand breaks. We show that deletion of Spo11 prevented genetic recombination between homologous chromosomes during the C. albicans parasexual cycle. These findings suggest that at least one meiosis-specific gene has been re-programmed to mediate genetic recombination during the alternative parasexual life cycle of C. albicans. We discuss, in light of the long association of C. albicans wit
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The parasexual cycle in Candida albicans provides an alternative pathway to meiosis for the formation of recombinant strains
PLoS Biology, 2008Co-Authors: Anja Forche, Dana Schaefer, Judith Berman, Kevin Alby, Alexander D Johnson, Richard J. BennettAbstract:Candida albicans has an elaborate, yet efficient, mating system that promotes conjugation between diploid a and alpha strains. The product of mating is a tetraploid a/alpha cell that must undergo a reductional division to return to the diploid state. Despite the presence of several "meiosis-specific" genes in the C. albicans genome, a meiotic program has not been observed. Instead, tetraploid products of mating can be induced to undergo efficient, random chromosome loss, often producing strains that are diploid, or close to diploid, in ploidy. Using SNP and comparative genome hybridization arrays we have now analyzed the genotypes of products from the C. albicans parasexual cycle. We show that the parasexual cycle generates progeny strains with shuffled combinations of the eight C. albicans chromosomes. In addition, several isolates had undergone extensive genetic recombination between homologous chromosomes, including multiple gene conversion events. Progeny strains exhibited altered colony morphologies on laboratory media, demonstrating that the parasexual cycle generates phenotypic variants of C. albicans. In several fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, the conserved Spo11 Protein is integral to meiotic recombination, where it is required for the formation of DNA double-strand breaks. We show that deletion of Spo11 prevented genetic recombination between homologous chromosomes during the C. albicans parasexual cycle. These findings suggest that at least one meiosis-specific gene has been re-programmed to mediate genetic recombination during the alternative parasexual life cycle of C. albicans. We discuss, in light of the long association of C. albicans with warm-blooded animals, the potential advantages of a parasexual cycle over a conventional sexual cycle.