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Regulation Mechanisms of Meiotic Recombination Revealed from the Analysis of a Fission Yeast Recombination Hotspot ade6-M26. Biomolecules 2022; 12:biom12121761. [PMID: 36551189 PMCID: PMC9775316 DOI: 10.3390/biom12121761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 11/29/2022] Open
Abstract
Meiotic recombination is a pivotal event that ensures faithful chromosome segregation and creates genetic diversity in gametes. Meiotic recombination is initiated by programmed double-strand breaks (DSBs), which are catalyzed by the conserved Spo11 protein. Spo11 is an enzyme with structural similarity to topoisomerase II and induces DSBs through the nucleophilic attack of the phosphodiester bond by the hydroxy group of its tyrosine (Tyr) catalytic residue. DSBs caused by Spo11 are repaired by homologous recombination using homologous chromosomes as donors, resulting in crossovers/chiasmata, which ensure physical contact between homologous chromosomes. Thus, the site of meiotic recombination is determined by the site of the induced DSB on the chromosome. Meiotic recombination is not uniformly induced, and sites showing high recombination rates are referred to as recombination hotspots. In fission yeast, ade6-M26, a nonsense point mutation of ade6 is a well-characterized meiotic recombination hotspot caused by the heptanucleotide sequence 5'-ATGACGT-3' at the M26 mutation point. In this review, we summarize the meiotic recombination mechanisms revealed by the analysis of the fission ade6-M26 gene as a model system.
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2
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Morgan C, Nayak A, Hosoya N, Smith GR, Lambing C. Meiotic chromosome organization and its role in recombination and cancer. Curr Top Dev Biol 2022; 151:91-126. [PMID: 36681479 PMCID: PMC10022578 DOI: 10.1016/bs.ctdb.2022.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Chromosomes adopt specific conformations to regulate various cellular processes. A well-documented chromosome configuration is the highly compacted chromosome structure during metaphase. More regional chromatin conformations have also been reported, including topologically associated domains encompassing mega-bases of DNA and local chromatin loops formed by kilo-bases of DNA. In this review, we discuss the changes in chromatin conformation taking place between somatic and meiotic cells, with a special focus on the establishment of a proteinaceous structure, called the chromosome axis, at the beginning of meiosis. The chromosome axis is essential to support key meiotic processes such as chromosome pairing, homologous recombination, and balanced chromosome segregation to transition from a diploid to a haploid stage. We review the role of the chromosome axis in meiotic chromatin organization and provide a detailed description of its protein composition. We also review the conserved and distinct roles between species of axis proteins in meiotic recombination, which is a major factor contributing to the creation of genetic diversity and genome evolution. Finally, we discuss situations where the chromosome axis is deregulated and evaluate the effects on genome integrity and the consequences from protein deregulation in meiocytes exposed to heat stress, and aberrant expression of genes encoding axis proteins in mammalian somatic cells associated with certain types of cancers.
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Affiliation(s)
| | - Aditya Nayak
- Department of Biology, Institute of Molecular Plant Biology, Swiss Federal Institute of Technology (ETH) Zurich, Zürich, Switzerland
| | - Noriko Hosoya
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, United States
| | - Christophe Lambing
- Plant Science Department, Rothamsted Research, Harpenden, United Kingdom.
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3
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Lorenz A, Mpaulo SJ. Gene conversion: a non-Mendelian process integral to meiotic recombination. Heredity (Edinb) 2022; 129:56-63. [PMID: 35393552 PMCID: PMC9273591 DOI: 10.1038/s41437-022-00523-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 12/30/2022] Open
Abstract
Meiosis is undoubtedly the mechanism that underpins Mendelian genetics. Meiosis is a specialised, reductional cell division which generates haploid gametes (reproductive cells) carrying a single chromosome complement from diploid progenitor cells harbouring two chromosome sets. Through this process, the hereditary material is shuffled and distributed into haploid gametes such that upon fertilisation, when two haploid gametes fuse, diploidy is restored in the zygote. During meiosis the transient physical connection of two homologous chromosomes (one originally inherited from each parent) each consisting of two sister chromatids and their subsequent segregation into four meiotic products (gametes), is what enables genetic marker assortment forming the core of Mendelian laws. The initiating events of meiotic recombination are DNA double-strand breaks (DSBs) which need to be repaired in a certain way to enable the homologous chromosomes to find each other. This is achieved by DSB ends searching for homologous repair templates and invading them. Ultimately, the repair of meiotic DSBs by homologous recombination physically connects homologous chromosomes through crossovers. These physical connections provided by crossovers enable faithful chromosome segregation. That being said, the DSB repair mechanism integral to meiotic recombination also produces genetic transmission distortions which manifest as postmeiotic segregation events and gene conversions. These processes are non-reciprocal genetic exchanges and thus non-Mendelian.
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Affiliation(s)
- Alexander Lorenz
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK.
| | - Samantha J Mpaulo
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK
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4
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Schizosaccharomyces pombe Assays to Study Mitotic Recombination Outcomes. Genes (Basel) 2020; 11:genes11010079. [PMID: 31936815 PMCID: PMC7016768 DOI: 10.3390/genes11010079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/07/2020] [Accepted: 01/07/2020] [Indexed: 01/16/2023] Open
Abstract
The fission yeast—Schizosaccharomyces pombe—has emerged as a powerful tractable system for studying DNA damage repair. Over the last few decades, several powerful in vivo genetic assays have been developed to study outcomes of mitotic recombination, the major repair mechanism of DNA double strand breaks and stalled or collapsed DNA replication forks. These assays have significantly increased our understanding of the molecular mechanisms underlying the DNA damage response pathways. Here, we review the assays that have been developed in fission yeast to study mitotic recombination.
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5
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Abstract
During meiosis, homologous chromosomes of a diploid cell are replicated and, without a second replication, are segregated during two nuclear divisions to produce four haploid cells (including discarded polar bodies in females of many species). Proper segregation of chromosomes at the first division requires in most species that homologous chromosomes be physically connected. Tension generated by connected chromosomes moving to opposite sides of the cell signals proper segregation. In the absence of the required connections, called crossovers, chromosomes often segregate randomly and produce aneuploid gametes and, thus, dead or disabled progeny. To be effective, crossovers must be properly distributed along chromosomes. Crossovers within or too near the centromere interfere with proper segregation; crossovers too near each other can ablate the required tension; and crossovers too concentrated in only one or a few regions would not re-assort most genetic characters important for evolution. Here, we discuss current knowledge of how the optimal distribution of crossovers is achieved in the fission yeast Schizosaccharomyces pombe, with reference to other well-studied species for comparison and illustration of the diversity of biology.
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Affiliation(s)
- Mridula Nambiar
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA, 98112, United States
| | - Yu-Chien Chuang
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA, 98112, United States
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA, 98112, United States.
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6
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Fowler KR, Hyppa RW, Cromie GA, Smith GR. Physical basis for long-distance communication along meiotic chromosomes. Proc Natl Acad Sci U S A 2018; 115:E9333-E9342. [PMID: 30217891 PMCID: PMC6176642 DOI: 10.1073/pnas.1801920115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Viable gamete formation requires segregation of homologous chromosomes connected, in most species, by cross-overs. DNA double-strand break (DSB) formation and the resulting cross-overs 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 (an 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 within 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 propose a model and discuss variations in which clustering and competition between DSB sites leads to DSB interference and in turn produces crossover interference.
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Affiliation(s)
- Kyle R Fowler
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Randy W Hyppa
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Gareth A Cromie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
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A Heterochromatin Domain Forms Gradually at a New Telomere and Is Dynamic at Stable Telomeres. Mol Cell Biol 2018; 38:MCB.00393-17. [PMID: 29784772 PMCID: PMC6048312 DOI: 10.1128/mcb.00393-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 05/09/2018] [Indexed: 02/03/2023] Open
Abstract
Heterochromatin domains play important roles in chromosome biology, organismal development, and aging, including centromere function, mammalian female X chromosome inactivation, and senescence-associated heterochromatin foci. In the fission yeast Schizosaccharomyces pombe and metazoans, heterochromatin contains histone H3 that is dimethylated at lysine 9. Heterochromatin domains play important roles in chromosome biology, organismal development, and aging, including centromere function, mammalian female X chromosome inactivation, and senescence-associated heterochromatin foci. In the fission yeast Schizosaccharomyces pombe and metazoans, heterochromatin contains histone H3 that is dimethylated at lysine 9. While factors required for heterochromatin have been identified, the dynamics of heterochromatin formation are poorly understood. Telomeres convert adjacent chromatin into heterochromatin. To form a new heterochromatic region in S. pombe, an inducible DNA double-strand break (DSB) was engineered next to 48 bp of telomere repeats in euchromatin, which caused formation of a new telomere and the establishment and gradual spreading of a new heterochromatin domain. However, spreading was dynamic even after the telomere had reached its stable length, with reporter genes within the heterochromatin domain showing variegated expression. The system also revealed the presence of repeats located near the boundaries of euchromatin and heterochromatin that are oriented to allow the efficient healing of a euchromatic DSB to cap the chromosome end with a new telomere. Telomere formation in S. pombe therefore reveals novel aspects of heterochromatin dynamics and fail-safe mechanisms to repair subtelomeric breaks, with implications for similar processes in metazoan genomes.
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Hyppa RW, Fowler KR, Smith GR. Quantitative Genome-Wide Measurements of Meiotic DNA Double-Strand Breaks and Protein Binding in S. pombe. Methods Mol Biol 2017; 1471:25-49. [PMID: 28349389 PMCID: PMC5771505 DOI: 10.1007/978-1-4939-6340-9_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
The fission yeast Schizosaccharomyces pombe is especially well suited for studying meiosis in molecular detail. Experiments with S. pombe strains that undergo a nearly synchronous meiosis-at variable temperatures-have elucidated the mechanisms of meiotic progression and the proteins that are involved. For example, studies focused on the initiation of meiotic recombination by programmed DNA double-strand breaks (DSBs) have proven exceptionally informative. In meiosis, some regions of DNA have more frequent DSBs than the surrounding regions. These DSB hotspots can be visualized by Southern blot hybridization of restriction fragments ranging from kilobases (kb) to megabases (Mb) in size. More recently, the benefits of genome-wide analysis to map the distribution and frequency of meiotic DSBs have been attained, with resolution down to the nucleotide level. Infrequent, non-hotspot DSBs previously not detectable have been observed, creating a better understanding of how recombination is regulated. Additional genome-wide analyses have shown proteins that bind specifically to DSB hotspots, providing insight into how the DSB initiation complex functions. We describe here detailed methods for achieving these results.
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Affiliation(s)
- Randy W Hyppa
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Kyle R Fowler
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, CA, USA
| | - Gerald R Smith
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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9
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de Boer E, Jasin M, Keeney S. Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice. Genes Dev 2015; 29:1721-33. [PMID: 26251527 PMCID: PMC4561481 DOI: 10.1101/gad.265561.115] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/21/2015] [Indexed: 11/24/2022]
Abstract
In this study, de Boer et al. investigated the influence of sex and chromosomal location on mammalian recombination outcomes and showed in one example that double-strand breaks within a hot spot can adopt either crossover or noncrossover fates in males but rarely led to crossing over in females. The findings here demonstrate that the outcome of mammalian meiotic recombination can be biased and provide novel insight into recombination mechanisms. Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency.
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Affiliation(s)
- Esther de Boer
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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10
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Lam I, Keeney S. Mechanism and regulation of meiotic recombination initiation. Cold Spring Harb Perspect Biol 2014; 7:a016634. [PMID: 25324213 DOI: 10.1101/cshperspect.a016634] [Citation(s) in RCA: 279] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
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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Affiliation(s)
- Isabel Lam
- Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065 Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065
| | - Scott Keeney
- Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065 Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065
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11
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Fowler KR, Sasaki M, Milman N, Keeney S, Smith GR. Evolutionarily diverse determinants of meiotic DNA break and recombination landscapes across the genome. Genome Res 2014; 24:1650-64. [PMID: 25024163 PMCID: PMC4199369 DOI: 10.1101/gr.172122.114] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Fission yeast Rec12 (Spo11 homolog) initiates meiotic recombination by forming developmentally programmed DNA double-strand breaks (DSBs). DSB distributions influence patterns of heredity and genome evolution, but the basis of the highly nonrandom choice of Rec12 cleavage sites is poorly understood, largely because available maps are of relatively low resolution and sensitivity. Here, we determined DSBs genome-wide at near-nucleotide resolution by sequencing the oligonucleotides attached to Rec12 following DNA cleavage. The single oligonucleotide size class allowed us to deeply sample all break events. We find strong evidence across the genome for differential DSB repair accounting for crossover invariance (constant cM/kb in spite of DSB hotspots). Surprisingly, about half of all crossovers occur in regions where DSBs occur at low frequency and are widely dispersed in location from cell to cell. These previously undetected, low-level DSBs thus play an outsized and crucial role in meiosis. We further find that the influence of underlying nucleotide sequence and chromosomal architecture differs in multiple ways from that in budding yeast. DSBs are not strongly restricted to nucleosome-depleted regions, as they are in budding yeast, but are nevertheless spatially influenced by chromatin structure. Our analyses demonstrate that evolutionarily fluid factors contribute to crossover initiation and regulation.
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Affiliation(s)
- Kyle R Fowler
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Mariko Sasaki
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10065, USA
| | - Neta Milman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; Weill Graduate School of Medical Sciences of Cornell University, New York, New York 10065, USA; Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA;
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12
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Hyppa RW, Fowler KR, Cipak L, Gregan J, Smith GR. DNA intermediates of meiotic recombination in synchronous S. pombe at optimal temperature. Nucleic Acids Res 2014; 42:359-69. [PMID: 24089141 PMCID: PMC3874177 DOI: 10.1093/nar/gkt861] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 09/03/2013] [Accepted: 09/03/2013] [Indexed: 11/16/2022] Open
Abstract
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.
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Affiliation(s)
- Randy W. Hyppa
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA, 98109, USA, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria, Cancer Research Institute, Slovak Academy of Sciences, 83391 Bratislava, Slovak Republic Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava, Slovak Republic
| | - Kyle R. Fowler
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA, 98109, USA, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria, Cancer Research Institute, Slovak Academy of Sciences, 83391 Bratislava, Slovak Republic Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava, Slovak Republic
| | - Lubos Cipak
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA, 98109, USA, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria, Cancer Research Institute, Slovak Academy of Sciences, 83391 Bratislava, Slovak Republic Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava, Slovak Republic
| | - Juraj Gregan
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA, 98109, USA, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria, Cancer Research Institute, Slovak Academy of Sciences, 83391 Bratislava, Slovak Republic Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava, Slovak Republic
| | - Gerald R. Smith
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, WA, 98109, USA, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria, Cancer Research Institute, Slovak Academy of Sciences, 83391 Bratislava, Slovak Republic Department of Genetics, Faculty of Natural Sciences, Comenius University, Mlynska Dolina, 842 15 Bratislava, Slovak Republic
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Fowler KR, Gutiérrez-Velasco S, Martín-Castellanos C, Smith GR. Protein determinants of meiotic DNA break hot spots. Mol Cell 2013; 49:983-96. [PMID: 23395004 DOI: 10.1016/j.molcel.2013.01.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 11/15/2012] [Accepted: 01/03/2013] [Indexed: 11/29/2022]
Abstract
Meiotic recombination, crucial for proper chromosome segregation and genome evolution, is initiated by programmed DNA double-strand breaks (DSBs) in yeasts and likely all sexually reproducing species. In fission yeast, DSBs occur up to hundreds of times more frequently at special sites, called hot spots, than in other regions of the genome. What distinguishes hot spots from cold regions is an unsolved problem, although transcription factors determine some hot spots. We report the discovery that three coiled-coil proteins-Rec25, Rec27, and Mug20-bind essentially all hot spots with great specificity even without DSB formation. These small proteins are components of linear elements, are related to synaptonemal complex proteins, and are essential for nearly all DSBs at most hot spots. Our results indicate these hot spot determinants activate or stabilize the DSB-forming protein Rec12 (Spo11 homolog) rather than promote its binding to hot spots. We propose a paradigm for hot spot determination and crossover control by linear element proteins.
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Affiliation(s)
- Kyle R Fowler
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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14
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Yamada S, Ohta K, Yamada T. Acetylated Histone H3K9 is associated with meiotic recombination hotspots, and plays a role in recombination redundantly with other factors including the H3K4 methylase Set1 in fission yeast. Nucleic Acids Res 2013; 41:3504-17. [PMID: 23382177 PMCID: PMC3616738 DOI: 10.1093/nar/gkt049] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Histone modifications are associated with meiotic recombination hotspots, discrete sites with augmented recombination frequency. For example, trimethylation of histone H3 lysine4 (H3K4me3) marks most hotspots in budding yeast and mouse. Modified histones are known to regulate meiotic recombination partly by promoting DNA double-strand break (DSB) formation at hotspots, but the role and precise landscape of involved modifications remain unclear. Here, we studied hotspot-associated modifications in fission yeast and found general features: acetylation of H3 lysine9 (H3K9ac) is elevated, and H3K4me3 is not significantly enriched. Mutating H3K9 to non-acetylatable alanine mildly reduced levels of the DSB-inducing protein Rec12 (the fission yeast homologue of Spo11) and DSB at hotspots, indicating that H3K9ac may be involved in DSB formation by enhancing the interaction between Rec12 and hotspots. In addition, we found that the lack of the H3K4 methyltransferase Set1 generally increased Rec12 binding to chromatin but partially reduced DSB formation at some loci, suggesting that Set1 is also involved in DSB formation. These results suggest that meiotic DSB formation is redundantly regulated by multiple chromatin-related factors including H3K9ac and Set1 in fission yeast.
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Affiliation(s)
- Shintaro Yamada
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
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15
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Lui DY, Colaiácovo MP. Meiotic development in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:133-70. [PMID: 22872477 DOI: 10.1007/978-1-4614-4015-4_6] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Caenorhabditis elegans has become a powerful experimental organism with which to study meiotic processes that promote the accurate segregation of chromosomes during the generation of haploid gametes. Haploid reproductive cells are produced through one round of chromosome replication followed by two -successive cell divisions. Characteristic meiotic chromosome structure and dynamics are largely conserved in C. elegans. Chromosomes adopt a meiosis-specific structure by loading cohesin proteins, assembling axial elements, and acquiring chromatin marks. Homologous chromosomes pair and form physical connections though synapsis and recombination. Synaptonemal complex and crossover formation allow for the homologs to stably associate prior to remodeling that facilitates their segregation. This chapter will cover conserved meiotic processes as well as highlight aspects of meiosis that are unique to C. elegans.
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Affiliation(s)
- Doris Y Lui
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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Wehrkamp-Richter S, Hyppa RW, Prudden J, Smith GR, Boddy MN. Meiotic DNA joint molecule resolution depends on Nse5-Nse6 of the Smc5-Smc6 holocomplex. Nucleic Acids Res 2012; 40:9633-46. [PMID: 22855558 PMCID: PMC3479181 DOI: 10.1093/nar/gks713] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Faithful chromosome segregation in meiosis is crucial to form viable, healthy offspring and in most species, it requires programmed recombination between homologous chromosomes. In fission yeast, meiotic recombination is initiated by Rec12 (Spo11 homolog) and generates single Holliday junction (HJ) intermediates, which are resolved by the Mus81–Eme1 endonuclease to generate crossovers and thereby allow proper chromosome segregation. Although Mus81 contains the active site for HJ resolution, the regulation of Mus81–Eme1 is unclear. In cells lacking Nse5–Nse6 of the Smc5–Smc6 genome stability complex, we observe persistent meiotic recombination intermediates (DNA joint molecules) resembling HJs that accumulate in mus81Δ cells. Elimination of Rec12 nearly completely rescues the meiotic defects of nse6Δ and mus81Δ single mutants and partially rescues nse6Δ mus81Δ double mutants, indicating that these factors act after DNA double-strand break formation. Likewise, expression of the bacterial HJ resolvase RusA partially rescues the defects of nse6Δ, mus81Δ and nse6Δ mus81Δ mitotic cells, as well as the meiotic defects of nse6Δ and mus81Δ cells. Partial rescue likely reflects the accumulation of structures other than HJs, such as hemicatenanes, and an additional role for Nse5–Nse6 most prominent during mitotic growth. Our results indicate a regulatory role for the Smc5–Smc6 complex in HJ resolution via Mus81–Eme1.
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Abstract
Hotspots regulate the position and frequency of Spo11 (Rec12)-initiated meiotic recombination, but paradoxically they are suicidal and are somehow resurrected elsewhere in the genome. After the DNA sequence-dependent activation of hotspots was discovered in fission yeast, nearly two decades elapsed before the key realizations that (A) DNA site-dependent regulation is broadly conserved and (B) individual eukaryotes have multiple different DNA sequence motifs that activate hotspots. From our perspective, such findings provide a conceptually straightforward solution to the hotspot paradox and can explain other, seemingly complex features of meiotic recombination. We describe how a small number of single-base-pair substitutions can generate hotspots de novo and dramatically alter their distribution in the genome. This model also shows how equilibrium rate kinetics could maintain the presence of hotspots over evolutionary timescales, without strong selective pressures invoked previously, and explains why hotspots localize preferentially to intergenic regions and introns. The model is robust enough to account for all hotspots of humans and chimpanzees repositioned since their divergence from the latest common ancestor.
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18
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Nucleosomal organization of replication origins and meiotic recombination hotspots in fission yeast. EMBO J 2011; 31:124-37. [PMID: 21989386 DOI: 10.1038/emboj.2011.350] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 08/31/2011] [Indexed: 12/17/2022] Open
Abstract
In Schizosaccharomyces pombe, DNA replication origins (ORIs) and meiotic recombination hotspots lack consensus sequences and show a bias towards mapping to large intergenic regions (IGRs). To explore whether this preference depended on underlying chromatin features, we have generated genome-wide nucleosome profiles during mitosis and meiosis. We have found that meiotic double-strand break sites (DSBs) colocalize with nucleosome-depleted regions (NDRs) and that large IGRs include clusters of NDRs that overlap with almost half of all DSBs. By contrast, ORIs do not colocalize with NDRs and they are regulated independently of DSBs. Physical relocation of NDRs at ectopic loci or modification of their genomic distribution during meiosis was paralleled by the generation of new DSB sites. Over 80% of all meiotic DSBs colocalize with NDRs that are also present during mitosis, indicating that the recombination pattern is largely dependent on constitutive properties of the genome and, to a lesser extent, on the transcriptional profile during meiosis. The organization of ORIs and of DSBs regions in S. pombe reveals similarities and differences relative to Saccharomyces cerevisiae.
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Phadnis N, Hyppa RW, Smith GR. New and old ways to control meiotic recombination. Trends Genet 2011; 27:411-21. [PMID: 21782271 PMCID: PMC3177014 DOI: 10.1016/j.tig.2011.06.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 06/15/2011] [Accepted: 06/16/2011] [Indexed: 11/25/2022]
Abstract
The unique segregation of homologs, rather than sister chromatids, at the first meiotic division requires the formation of crossovers (COs) between homologs by meiotic recombination in most species. Crossovers do not form at random along chromosomes. Rather, their formation is carefully controlled, both at the stage of formation of DNA double-strand breaks (DSBs) that can initiate COs and during the repair of these DSBs. Here, we review control of DSB formation and two recently recognized controls of DSB repair: CO homeostasis and CO invariance. Crossover homeostasis maintains a constant number of COs per cell when the total number of DSBs in a cell is experimentally or stochastically reduced. Crossover invariance maintains a constant CO density (COs per kb of DNA) across much of the genome despite strong DSB hotspots in some intervals. These recently uncovered phenomena show that CO control is even more complex than previously suspected.
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Affiliation(s)
- Naina Phadnis
- Fred Hutchinson Cancer Research Center 1100 Fairview Avenue North Seattle, WA 98109 USA
| | - Randy W. Hyppa
- Fred Hutchinson Cancer Research Center 1100 Fairview Avenue North Seattle, WA 98109 USA
| | - Gerald R. Smith
- Fred Hutchinson Cancer Research Center 1100 Fairview Avenue North Seattle, WA 98109 USA
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20
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Kan F, Davidson MK, Wahls WP. Meiotic recombination protein Rec12: functional conservation, crossover homeostasis and early crossover/non-crossover decision. Nucleic Acids Res 2010; 39:1460-72. [PMID: 21030440 PMCID: PMC3045620 DOI: 10.1093/nar/gkq993] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In fission yeast and other eukaryotes, Rec12 (Spo11) is thought to catalyze the formation of dsDNA breaks (DSBs) that initiate homologous recombination in meiosis. Rec12 is orthologous to the catalytic subunit of topoisomerase VI (Top6A). Guided by the crystal structure of Top6A, we engineered the rec12 locus to encode Rec12 proteins each with a single amino acid substitution in a conserved residue. Of 21 substitutions, 10 significantly reduced or abolished meiotic DSBs, gene conversion, crossover recombination and the faithful segregation of chromosomes. Critical residues map within the metal ion-binding pocket toprim (E179A, D229A, D231A), catalytic region 5Y-CAP (R94A, D95A, Y98F) and the DNA-binding interface (K201A, G202E, R209A, K242A). A subset of substitutions reduced DSBs but maintained crossovers, demonstrating crossover homeostasis. Furthermore, a strong separation of function mutation (R304A) suggests that the crossover/non-crossover decision is established early by a protein–protein interaction surface of Rec12. Fission yeast has multiple crossovers per bivalent, and chromosome segregation was robust above a threshold of about one crossover per bivalent, below which non-disjunction occurred. These results support structural and functional conservation among Rec12/Spo11/Top6A family members for the catalysis of DSBs, and they reveal how Rec12 regulates other features of meiotic chromosome dynamics.
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Affiliation(s)
- Fengling Kan
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street (slot 516), Little Rock, AR 72205-7199, USA
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21
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Hyppa RW, Smith GR. Crossover invariance determined by partner choice for meiotic DNA break repair. Cell 2010; 142:243-55. [PMID: 20655467 PMCID: PMC2911445 DOI: 10.1016/j.cell.2010.05.041] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 03/23/2010] [Accepted: 05/18/2010] [Indexed: 11/21/2022]
Abstract
Crossovers between meiotic homologs are crucial for their proper segregation, and crossover number and position are carefully controlled. Crossover homeostasis in budding yeast maintains crossovers at the expense of noncrossovers when double-strand DNA break (DSB) frequency is reduced. The mechanism of maintaining constant crossover levels in other species has been unknown. Here we investigate in fission yeast a different aspect of crossover control--the near invariance of crossover frequency per kb of DNA despite large variations in DSB intensity across the genome. Crossover invariance involves the choice of sister chromatid versus homolog for DSB repair. At strong DSB hotspots, intersister repair outnumbers interhomolog repair approximately 3:1, but our genetic and physical data indicate the converse in DSB-cold regions. This unanticipated mechanism of crossover control may operate in many species and explain, for example, the large excess of DSBs over crossovers and the repair of DSBs on unpaired chromosomes in diverse species.
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Affiliation(s)
- Randy W. Hyppa
- Fred Hutchinson Cancer Research Center Division of Basic Sciences Seattle, WA 98109 USA
| | - Gerald R. Smith
- Fred Hutchinson Cancer Research Center Division of Basic Sciences Seattle, WA 98109 USA
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Ctp1 and Exonuclease 1, alternative nucleases regulated by the MRN complex, are required for efficient meiotic recombination. Proc Natl Acad Sci U S A 2009; 106:9356-61. [PMID: 19470480 DOI: 10.1073/pnas.0902793106] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Double-strand breaks (DSBs) in DNA are lethal unless repaired. Faithful repair requires processing of the DSB ends and interaction with intact homologous DNA, which can produce genetic recombinants. To determine the role of nucleases in DSB end-processing and joint molecule resolution, we studied recombination at the site of a single DSB, generated by induction of the I-SceI endonuclease, during meiosis of fission yeast lacking Rec12 (Spo11 homolog) and, hence, other DSBs. We find that in the presence of the MRN (Rad32-Rad50-Nbs1) complex efficient recombination requires Ctp1, the ortholog of the nuclease Sae2, but not the nuclease activity of MRN. In the absence of MRN, exonuclease 1 (Exo1) becomes the major nuclease required for efficient recombination. Our data indicate that MRN enables access of Ctp1 to the DSB but blocks access of Exo1. In our assay, the Rad16-Swi10 nuclease, required for nucleotide excision-repair, is required for efficient recombination, presumably to remove heterologous DNA at the end of the I-SceI cut site. Another nuclease, the Mus81-Eme1 Holliday junction resolvase, is required to generate crossovers accompanying gene conversion at the I-SceI cut site. Additional, previously published evidence indicates that these 5 nucleases play similar roles in wild-type fission yeast meiotic recombination and in the repair of spontaneous and damage-induced mitotic DSBs. We propose that in wild-type meiosis MRN, in conjunction with Ctp1, removes the covalently attached Rec12 protein from the DNA end, which is then resected by Ctp1 and other activities to produce the single-stranded DNA necessary for further steps of DSB repair.
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Parvanov ED, Ng SHS, Petkov PM, Paigen K. Trans-regulation of mouse meiotic recombination hotspots by Rcr1. PLoS Biol 2009; 7:e36. [PMID: 19226189 PMCID: PMC2642880 DOI: 10.1371/journal.pbio.1000036] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 01/07/2009] [Indexed: 11/20/2022] Open
Abstract
Meiotic recombination is required for the orderly segregation of chromosomes during meiosis and for providing genetic diversity among offspring. Among mammals, as well as yeast and higher plants, recombination preferentially occurs at highly delimited chromosomal sites 1–2 kb long known as hotspots. Although considerable progress has been made in understanding the roles various proteins play in carrying out the molecular events of the recombination process, relatively little is understood about the factors controlling the location and relative activity of mammalian recombination hotspots. To search for trans-acting factors controlling the positioning of recombination events, we compared the locations of crossovers arising in an 8-Mb segment of a 100-Mb region of mouse Chromosome 1 (Chr 1) when the longer region was heterozygous C57BL/6J (B6) × CAST/EiJ (CAST) and the remainder of the genome was either similarly heterozygous or entirely homozygous B6. The lack of CAST alleles in the remainder of the genome resulted in profound changes in hotspot activity in both females and males. Recombination activity was lost at several hotspots; new, previously undetected hotspots appeared; and still other hotspots remained unaffected, indicating the presence of distant trans-acting gene(s) whose CAST allele(s) activate or suppress the activity of specific hotspots. Testing the activity of three activated hotspots in sperm samples from individual male progeny of two genetic crosses, we identified a single trans-acting regulator of hotspot activity, designated Rcr1, that is located in a 5.30-Mb interval (11.74–17.04 Mb) on Chr 17. Using an Escherichia coli cloning assay to characterize the molecular products of recombination at two of these hotspots, we found that Rcr1 controls the appearance of both crossover and noncrossover gene conversion events, indicating that it likely controls the sites of the double-strand DNA breaks that initiate the recombination process. Recombination is an essential aspect of meiosis, ensuring proper contact and exchange of genetic material between homologous parental chromosomes, as well as their subsequent segregation to produce haploid gametes. In humans and mice, recombination events are located at preferential sites termed hotspots, whose placement and activity are tightly regulated. We have now identified a hotspot-regulating locus in mammals, Rcr1, that simultaneously controls the locations of multiple hotspots. The discovery of Rcr1 indicates the existence of a newly emerging class of genes important in the recombination processes. Gaining further insights into their function may contribute to a better understanding of genetic factors underlying human fertility and evolution. Rcr1 is identified as atrans-regulator of meiotic recombination hotspots that appears to act at the initiation of recombination and that maps to a 5.3-megabase region on mouse Chromosome 17.
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Novel nucleotide sequence motifs that produce hotspots of meiotic recombination in Schizosaccharomyces pombe. Genetics 2009; 182:459-69. [PMID: 19363124 DOI: 10.1534/genetics.109.101253] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many organisms, including yeasts and humans, meiotic recombination is initiated preferentially at a limited number of sites in the genome referred to as recombination hotspots. Predicting precisely the location of most hotspots has remained elusive. In this study, we tested the hypothesis that hotspots can result from multiple different sequence motifs. We devised a method to rapidly screen many short random oligonucleotide sequences for hotspot activity in the fission yeast Schizosaccharomyces pombe and produced a library of approximately 500 unique 15- and 30-bp sequences containing hotspots. The frequency of hotspots found suggests that there may be a relatively large number of different sequence motifs that produce hotspots. Within our sequence library, we found many shorter 6- to 10-bp motifs that occurred multiple times, many of which produced hotspots when reconstructed in vivo. On the basis of sequence similarity, we were able to group those hotspots into five different sequence families. At least one of the novel hotspots we found appears to be a target for a transcription factor, as it requires that factor for its hotspot activity. We propose that many hotspots in S. pombe, and perhaps other organisms, result from simple sequence motifs, some of which are identified here.
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25
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Hyppa RW, Cromie GA, Smith GR. Indistinguishable landscapes of meiotic DNA breaks in rad50+ and rad50S strains of fission yeast revealed by a novel rad50+ recombination intermediate. PLoS Genet 2008; 4:e1000267. [PMID: 19023408 PMCID: PMC2580034 DOI: 10.1371/journal.pgen.1000267] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 10/16/2008] [Indexed: 12/03/2022] Open
Abstract
The fission yeast Schizosaccharomyces pombe Rec12 protein, the homolog of Spo11 in other organisms, initiates meiotic recombination by creating DNA double-strand breaks (DSBs) and becoming covalently linked to the DNA ends of the break. This protein–DNA linkage has previously been detected only in mutants such as rad50S in which break repair is impeded and DSBs accumulate. In the budding yeast Saccharomyces cerevisiae, the DSB distribution in a rad50S mutant is markedly different from that in wild-type (RAD50) meiosis, and it was suggested that this might also be true for other organisms. Here, we show that we can detect Rec12-DNA linkages in Sc. pombe rad50+ cells, which are proficient for DSB repair. In contrast to the results from Sa. cerevisiae, genome-wide microarray analysis of Rec12-DNA reveals indistinguishable meiotic DSB distributions in rad50+ and rad50S strains of Sc. pombe. These results confirm our earlier findings describing the occurrence of widely spaced DSBs primarily in large intergenic regions of DNA and demonstrate the relevance and usefulness of fission yeast studies employing rad50S. We propose that the differential behavior of rad50S strains reflects a major difference in DSB regulation between the two species—specifically, the requirement for the Rad50-containing complex for DSB formation in budding yeast but not in fission yeast. Use of rad50S and related mutations may be a useful method for DSB analysis in other species. During meiosis, which creates haploid gametes from diploid cells, recombination between two homologous chromosomes increases genetic diversity and, in most organisms, is crucial for proper segregation of chromosomes into haploid nuclei. To better understand where recombination occurs and why it occurs there, we investigated in fission yeast the initiating step in recombination—formation of DNA double-strand breaks (DSBs). A genome-wide DSB map is crucial to understand how DNA sequence and chromatin structure affect DSB formation and may help answer these questions in other organisms, including humans. Mutants in which DSBs accumulate are particularly useful for determining the DSB distribution. As recently reported, however, in budding yeast the DSB distribution in one such widely used mutant, rad50S, differs markedly from that in a dmc1 mutant, in which DSBs also accumulate and appear to have a more nearly wild-type distribution. We have detected in fission yeast a DNA–protein intermediate of recombination assumed to exist, but never before detected, in a recombination-proficient strain (rad50+). The distributions of this intermediate, and therefore those of DSBs, in rad50+ and rad50S strains are indistinguishable. rad50S-like mutations may also accurately reflect the wild-type DSB distribution in other species and may be particularly useful in species lacking Dmc1 orthologs.
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Affiliation(s)
- Randy W. Hyppa
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Gareth A. Cromie
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Gerald R. Smith
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail:
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26
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Ludin K, Mata J, Watt S, Lehmann E, Bähler J, Kohli J. Sites of strong Rec12/Spo11 binding in the fission yeast genome are associated with meiotic recombination and with centromeres. Chromosoma 2008; 117:431-44. [PMID: 18449558 PMCID: PMC3671157 DOI: 10.1007/s00412-008-0159-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 03/14/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
Abstract
Meiotic recombination arises from Rec12/Spo11-dependent formation of DNA double-strand breaks (DSBs) and their subsequent repair. We identified Rec12-binding peaks across the Schizosaccharomyces pombe genome using chromatin immunoprecipitation after reversible formaldehyde cross-linking combined with whole-genome DNA microarrays. Strong Rec12 binding coincided with previously identified DSBs at the recombination hotspots ura4A, mbs1, and mbs2 and correlated with DSB formation at a new site. In addition, Rec12 binding corresponded to eight novel conversion hotspots and correlated with crossover density in segments of chromosome I. Notably, Rec12 binding inversely correlated with guanine-cytosine (GC) content, contrary to findings in Saccharomyces cerevisiae. Although both replication origins and Rec12-binding sites preferred AT-rich gene-free regions, they seemed to exclude each other. We also uncovered a connection between binding sites of Rec12 and meiotic cohesin Rec8. Rec12-binding peaks lay often within 2.5 kb of a Rec8-binding peak. Rec12 binding showed preference for large intergenic regions and was found to bind preferentially near to genes expressed strongly in meiosis. Surprisingly, Rec12 binding was also detected in centromeric core regions, which raises the intriguing possibility that Rec12 plays additional roles in meiotic chromosome dynamics.
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Affiliation(s)
- Katja Ludin
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
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Cromie GA, Hyppa RW, Smith GR. The fission yeast BLM homolog Rqh1 promotes meiotic recombination. Genetics 2008; 179:1157-67. [PMID: 18562672 PMCID: PMC2475723 DOI: 10.1534/genetics.108.088955] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 03/31/2008] [Indexed: 01/04/2023] Open
Abstract
RecQ helicases are found in organisms as diverse as bacteria, fungi, and mammals. These proteins promote genome stability, and mutations affecting human RecQ proteins underlie premature aging and cancer predisposition syndromes, including Bloom syndrome, caused by mutations affecting the BLM protein. In this study we show that mutants lacking the Rqh1 protein of the fission yeast Schizosaccharomyces pombe, a RecQ and BLM homolog, have substantially reduced meiotic recombination, both gene conversions and crossovers. The relative proportion of gene conversions having associated crossovers is unchanged from that in wild type. In rqh1 mutants, meiotic DNA double-strand breaks are formed and disappear with wild-type frequency and kinetics, and spore viability is only moderately reduced. Genetic analyses and the wild-type frequency of both intersister and interhomolog joint molecules argue against these phenotypes being explained by an increase in intersister recombination at the expense of interhomolog recombination. We suggest that Rqh1 extends hybrid DNA and biases the recombination outcome toward crossing over. Our results contrast dramatically with those from the budding yeast ortholog, Sgs1, which has a meiotic antirecombination function that suppresses recombination events involving more than two DNA duplexes. These observations underscore the multiple recombination functions of RecQ homologs and emphasize that even conserved proteins can be adapted to play different roles in different organisms.
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Affiliation(s)
- Gareth A Cromie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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28
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Meiotic Chromatin: The Substrate for Recombination Initiation. RECOMBINATION AND MEIOSIS 2008. [DOI: 10.1007/7050_2008_040] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Peters AD. A combination of cis and trans control can solve the hotspot conversion paradox. Genetics 2008; 178:1579-93. [PMID: 18245829 PMCID: PMC2278049 DOI: 10.1534/genetics.107.084061] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 01/02/2008] [Indexed: 01/06/2023] Open
Abstract
There is growing evidence that in a variety of organisms the majority of meiotic recombination events occur at a relatively small fraction of loci, known as recombination hotspots. If hotspot activity results from the DNA sequence at or near the hotspot itself (in cis), these hotspots are expected to be rapidly lost due to biased gene conversion, unless there is strong selection in favor of the hotspot itself. This phenomenon makes it very difficult to maintain existing hotspots and even more difficult for new hotspots to evolve; it has therefore come to be known as the "hotspot conversion paradox." I develop an analytical framework for exploring the evolution of recombination hotspots under the forces of selection, mutation, and conversion. I derive the general conditions under which cis- and trans-controlled hotspots can be maintained, as well as those under which new hotspots controlled by both a cis and a trans locus can invade a population. I show that the conditions for maintenance of and invasion by trans- or cis-plus-trans-controlled hotspots are broader than for those controlled entirely in cis. Finally, I show that a combination of cis and trans control may allow for long-lived polymorphisms in hotspot activity, the patterns of which may explain some recently observed features of recombination hotspots.
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Affiliation(s)
- A D Peters
- Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706, USA.
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30
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Cromie G, Smith GR. Meiotic Recombination in Schizosaccharomyces pombe: A Paradigm for Genetic and Molecular Analysis. GENOME DYNAMICS AND STABILITY 2008; 3:195. [PMID: 20157622 DOI: 10.1007/7050_2007_025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The fission yeast Schizosaccharomyces pombe is especially well-suited for both genetic and biochemical analysis of meiotic recombination. Recent studies have revealed ~50 gene products and two DNA intermediates central to recombination, which we place into a pathway from parental to recombinant DNA. We divide recombination into three stages - chromosome alignment accompanying nuclear "horsetail" movement, formation of DNA breaks, and repair of those breaks - and we discuss the roles of the identified gene products and DNA intermediates in these stages. Although some aspects of recombination are similar to those in the distantly related budding yeast Saccharomyces cerevisiae, other aspects are distinctly different. In particular, many proteins required for recombination in one species have no clear ortholog in the other, and the roles of identified orthologs in regulating recombination often differ. Furthermore, in S. pombe the dominant joint DNA molecule intermediates contain single Holliday junctions, and intersister joint molecules are more frequent than interhomolog types, whereas in S. cerevisiae interhomolog double Holliday junctions predominate. We speculate that meiotic recombination in other organisms shares features of each of these yeasts.
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Affiliation(s)
- Gareth Cromie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, U. S. A
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31
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Hirota K, Steiner WW, Shibata T, Ohta K. Multiple modes of chromatin configuration at natural meiotic recombination hot spots in fission yeast. EUKARYOTIC CELL 2007; 6:2072-80. [PMID: 17827346 PMCID: PMC2168419 DOI: 10.1128/ec.00246-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ade6-M26 meiotic recombination hot spot of fission yeast is defined by a cyclic AMP-responsive element (CRE)-like heptanucleotide sequence, 5'-ATGACGT-3', which acts as a binding site for the Atf1/Pcr1 heterodimeric transcription factor required for hot spot activation. We previously demonstrated that the local chromatin around the M26 sequence motif alters to exhibit higher sensitivity to micrococcal nuclease before the initiation of meiotic recombination. In this study, we have examined whether or not such alterations in chromatin occur at natural meiotic DNA double-strand break (DSB) sites in Schizosaccharomyces pombe. At one of the most prominent DSB sites, mbs1 (meiotic break site 1), the chromatin structure has a constitutively accessible configuration at or near the DSB sites. The establishment of the open chromatin state and DSB formation are independent of the CRE-binding transcription factor, Atf1. Analysis of the chromatin configuration at CRE-dependent DSB sites revealed both differences from and similarities to mbs1. For example, the tdh1+ locus, which harbors a CRE consensus sequence near the DSB site, shows a meiotically induced open chromatin configuration, similar to ade6-M26. In contrast, the cds1+ locus is similar to mbs1 in that it exhibits a constitutive open configuration. Importantly, Atf1 is required for the open chromatin formation in both tdh1+ and cds1+. These results suggest that CRE-dependent meiotic chromatin changes are intrinsic processes related to DSB formation in fission yeast meiosis. In addition, the results suggest that the chromatin configuration in natural meiotic recombination hot spots can be classified into at least three distinct categories: (i) an Atf1-CRE-independent constitutively open chromatin configuration, (ii) an Atf1-CRE-dependent meiotically induced open chromatin configuration, and (iii) an Atf1-CRE-dependent constitutively open chromatin configuration.
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Affiliation(s)
- Kouji Hirota
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguroku, Tokyo 153-8902, Japan.
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32
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Cromie GA, Hyppa RW, Cam HP, Farah JA, Grewal SIS, Smith GR. A discrete class of intergenic DNA dictates meiotic DNA break hotspots in fission yeast. PLoS Genet 2007; 3:e141. [PMID: 17722984 PMCID: PMC1950956 DOI: 10.1371/journal.pgen.0030141] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 07/09/2007] [Indexed: 01/21/2023] Open
Abstract
Meiotic recombination is initiated by DNA double-strand breaks (DSBs) made by Spo11 (Rec12 in fission yeast), which becomes covalently linked to the DSB ends. Like recombination events, DSBs occur at hotspots in the genome, but the genetic factors responsible for most hotspots have remained elusive. Here we describe in fission yeast the genome-wide distribution of meiosis-specific Rec12-DNA linkages, which closely parallel DSBs measured by conventional Southern blot hybridization. Prominent DSB hotspots are located ∼65 kb apart, separated by intervals with little or no detectable breakage. Most hotspots lie within exceptionally large intergenic regions. Thus, the chromosomal architecture responsible for hotspots in fission yeast is markedly different from that of budding yeast, in which DSB hotspots are much more closely spaced and, in many regions of the genome, occur at each promoter. Our analysis in fission yeast reveals a clearly identifiable chromosomal feature that can predict the majority of recombination hotspots across a whole genome and provides a basis for searching for the chromosomal features that dictate hotspots of meiotic recombination in other organisms, including humans. Homologous genetic recombination has two immediate benefits for cells—faithfully repairing broken DNA and aiding chromosome segregation during the first division of meiosis. Meiosis comprises a pair of special nuclear divisions that convert diploid somatic cells into haploid sex cells; in humans, meiosis leads to formation of eggs and sperm. By introducing double-strand breaks (DSBs) into their own DNA during meiosis, organisms promote recombination and hence production of viable sex cells. Although meiotic DSBs, and therefore recombination, occur throughout genomes, they arise at high frequency in certain genomic regions called hotspots, whose molecular bases are rarely understood. In this article we determine the locations of DSBs across the entire genome of the fission yeast Schizosaccharomyces pombe by taking advantage of physical linkages between DNA and the protein Rec12 that makes DSBs. This analysis shows that most of the DSB hotspots are in exceptionally large intergenic (gene-free) regions spaced on average about 65 kb apart and making up only a small fraction of the genome. Between the hotspots we see very little evidence of DSBs. The concentration of hotspots in large intergenic regions suggests that DSBs may be determined by special nucleotide sequences buried in these regions. Determining these special sequences will allow predictions of hotspots and, perhaps, the proteins and features of genome architecture that lead to DSBs being made at these special sites.
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Affiliation(s)
- Gareth A Cromie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Randy W Hyppa
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Hugh P Cam
- Laboratory of Molecular Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Joseph A Farah
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Shiv I. S Grewal
- Laboratory of Molecular Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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33
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Fukuda T, Ohya Y, Ohta K. Conditional genomic rearrangement by designed meiotic recombination using VDE (PI-SceI) in yeast. Mol Genet Genomics 2007; 278:467-78. [PMID: 17587055 DOI: 10.1007/s00438-007-0264-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Accepted: 06/01/2007] [Indexed: 01/07/2023]
Abstract
Meiotic recombination plays critical roles in the acquisition of genetic diversity and has been utilized for conventional breeding of livestock and crops. The frequency of meiotic recombination is normally low, and is extremely low in regions called "recombination cold domains". Here, we describe a new and highly efficient method to modulate yeast meiotic gene rearrangements using VDE (PI-SceI), an intein-encoded endonuclease that causes an efficient unidirectional meiotic gene conversion at its recognition sequence (VRS). We designed universal targeting vectors, by use of which the strain that inserts the VRS at a desired site is acquired. Meiotic induction of the strains provided unidirectional gene conversions and frequent genetic rearrangements of flanking genes with little impact on cell viability. This system thus opens the way for the designed modulation of meiotic gene rearrangements, regardless of recombinational activity of chromosomal domains. Finally, the VDE-VRS system enabled us to conduct meiosis-specific conditional knockout of genes where VDE-initiated gene conversion disrupts the target gene during meiosis, serving as a novel approach to examine the functions of genes during germination of resultant spores.
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Affiliation(s)
- Tomoyuki Fukuda
- Genetic System Regulation Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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34
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Cromie GA, Hyppa RW, Taylor AF, Zakharyevich K, Hunter N, Smith GR. Single Holliday junctions are intermediates of meiotic recombination. Cell 2006; 127:1167-78. [PMID: 17174892 PMCID: PMC2803030 DOI: 10.1016/j.cell.2006.09.050] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 08/18/2006] [Accepted: 09/25/2006] [Indexed: 11/29/2022]
Abstract
Crossing-over between homologous chromosomes facilitates their accurate segregation at the first division of meiosis. Current models for crossing-over invoke an intermediate in which homologs are connected by two crossed-strand structures called Holliday junctions. Such double Holliday junctions are a prominent intermediate in Saccharomyces cerevisiae meiosis, where they form preferentially between homologs rather than between sister chromatids. In sharp contrast, we find that single Holliday junctions are the predominant intermediate in Schizosaccharomyces pombe meiosis. Furthermore, these single Holliday junctions arise preferentially between sister chromatids rather than between homologs. We show that Mus81 is required for Holliday junction resolution, providing further in vivo evidence that the structure-specific endonuclease Mus81-Eme1 is a Holliday junction resolvase. To reconcile these observations, we present a unifying recombination model applicable for both meiosis and mitosis in which single Holliday junctions arise from single- or double-strand breaks, lesions postulated by previous models to initiate recombination.
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Affiliation(s)
- Gareth A. Cromie
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, P.O. Box 19024, Seattle, WA 98109-1024
| | - Randy W. Hyppa
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, P.O. Box 19024, Seattle, WA 98109-1024
| | - Andrew F. Taylor
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, P.O. Box 19024, Seattle, WA 98109-1024
| | - Kseniya Zakharyevich
- Center for Genetics and Development, Sections of Microbiology and Molecular & Cellular Biology, University of California at Davis, One Shields Avenue, Davis, CA 95616
| | - Neil Hunter
- Center for Genetics and Development, Sections of Microbiology and Molecular & Cellular Biology, University of California at Davis, One Shields Avenue, Davis, CA 95616
| | - Gerald R. Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, P.O. Box 19024, Seattle, WA 98109-1024
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Wells JL, Pryce DW, Estreicher A, Loidl J, McFarlane RJ. Linear element-independent meiotic recombination in Schizosaccharomyces pombe. Genetics 2006; 174:1105-14. [PMID: 16980386 PMCID: PMC1667095 DOI: 10.1534/genetics.106.063818] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most organisms form protein-rich, linear, ladder-like structures associated with chromosomes during early meiosis, the synaptonemal complex. In Schizosaccharomyces pombe, linear elements (LinEs) are thread-like, proteinacious chromosome-associated structures that form during early meiosis. LinEs are related to axial elements, the synaptonemal complex precursors of other organisms. Previous studies have led to the suggestion that axial structures are essential to mediate meiotic recombination. Rec10 protein is a major component of S. pombe LinEs and is required for their development. In this report we study recombination in a number of rec10 mutants, one of which (rec10-155) does not form LinEs, but is predicted to encode a truncated Rec10 protein. This mutant has levels of crossing over and gene conversion substantially higher than a rec10 null mutant (rec10-175) and forms cytologically detectable Rad51 foci indicative of meiotic recombination intermediates. These data demonstrate that while Rec10 is required for meiotic recombination, substantial meiotic recombination can occur in rec10 mutants that do not form LinEs, indicating that LinEs per se are not essential for all meiotic recombination.
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Affiliation(s)
- Jennifer L Wells
- North West Research Fund Institute, University of Wales, Bangor, UK
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Davis L, Smith GR. The meiotic bouquet promotes homolog interactions and restricts ectopic recombination in Schizosaccharomyces pombe. Genetics 2006; 174:167-77. [PMID: 16988108 PMCID: PMC1569800 DOI: 10.1534/genetics.106.059733] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 07/06/2006] [Indexed: 11/18/2022] Open
Abstract
Chromosome architecture undergoes extensive, programmed changes as cells enter meiosis. A highly conserved change is the clustering of telomeres at the nuclear periphery to form the "bouquet" configuration. In the fission yeast Schizosaccharomyces pombe the bouquet and associated nuclear movement facilitate initial interactions between homologs. We show that Bqt2, a meiosis-specific protein required for bouquet formation, is required for wild-type levels of homolog pairing and meiotic allelic recombination. Both gene conversion and crossing over are reduced and exhibit negative interference in bqt2Delta mutants, reflecting reduced homolog pairing. While both the bouquet and nuclear movement promote pairing, only the bouquet restricts ectopic recombination (that between dispersed repetitive DNA). We discuss mechanisms by which the bouquet may prevent deleterious translocations by restricting ectopic recombination.
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Affiliation(s)
- Luther Davis
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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37
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Martín-Castellanos C, Blanco M, Rozalén AE, Pérez-Hidalgo L, García AI, Conde F, Mata J, Ellermeier C, Davis L, San-Segundo P, Smith GR, Moreno S. A large-scale screen in S. pombe identifies seven novel genes required for critical meiotic events. Curr Biol 2006; 15:2056-62. [PMID: 16303567 PMCID: PMC2721798 DOI: 10.1016/j.cub.2005.10.038] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 10/05/2005] [Accepted: 10/11/2005] [Indexed: 11/17/2022]
Abstract
Meiosis is a specialized form of cell division by which sexually reproducing diploid organisms generate haploid gametes. During a long prophase, telomeres cluster into the bouquet configuration to aid chromosome pairing, and DNA replication is followed by high levels of recombination between homologous chromosomes (homologs). This recombination is important for the reductional segregation of homologs at the first meiotic division; without further replication, a second meiotic division yields haploid nuclei. In the fission yeast Schizosaccharomyces pombe, we have deleted 175 meiotically upregulated genes and found seven genes not previously reported to be critical for meiotic events. Three mutants (rec24, rec25, and rec27) had strongly reduced meiosis-specific DNA double-strand breakage and recombination. One mutant (tht2) was deficient in karyogamy, and two (bqt1 and bqt2) were deficient in telomere clustering, explaining their defects in recombination and segregation. The moa1 mutant was delayed in premeiotic S phase progression and nuclear divisions. Further analysis of these mutants will help elucidate the complex machinery governing the special behavior of meiotic chromosomes.
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Affiliation(s)
- Cristina Martín-Castellanos
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Miguel Blanco
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Ana E. Rozalén
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Livia Pérez-Hidalgo
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Ana I. García
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Francisco Conde
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Juan Mata
- The Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Chad Ellermeier
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, U.S.A
| | - Luther Davis
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, U.S.A
| | - Pedro San-Segundo
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - Gerald R. Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, U.S.A
| | - Sergio Moreno
- Instituto de Biología Molecular y Celular del Cáncer, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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Lorenz A, Estreicher A, Kohli J, Loidl J. Meiotic recombination proteins localize to linear elements in Schizosaccharomyces pombe. Chromosoma 2006; 115:330-40. [PMID: 16532353 DOI: 10.1007/s00412-006-0053-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 01/12/2006] [Accepted: 01/13/2006] [Indexed: 10/24/2022]
Abstract
In fission yeast, meiotic prophase nuclei develop structures known as linear elements (LinEs), instead of a canonical synaptonemal complex. LinEs contain Rec10 protein. While Rec10 is essential for meiotic recombination, the precise role of LinEs in this process is unknown. Using in situ immunostaining, we show that Rec7 (which is required for meiosis-specific DNA double-strand break (DSB) formation) aggregates in foci on LinEs. The strand exchange protein Rad51, which is known to mark the sites of DSBs, also localizes to LinEs, although to a lesser degree. The number of Rec7 foci corresponds well with the average number of genetic recombination events per meiosis suggesting that Rec7 marks the sites of recombination. Rec7 and Rad51 foci do not co-localize, presumably because they act sequentially on recombination sites. The localization of Rec7 is dependent on Rec10 but independent of the DSB-inducing protein Rec12/Spo11. Neither Rec7 nor Rad51 localization depends on the LinE-associated proteins Hop1 and Mek1, but the formation of Rad51 foci depends on Rec10, Rec7, and, as expected, Rec12/Spo11. We propose that LinEs form around designated recombination sites before the induction of DSBs and that most, if not all, meiotic recombination initiates within the setting provided by LinEs.
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Affiliation(s)
- Alexander Lorenz
- Department of Chromosome Biology, University of Vienna, A-1030, Vienna, Austria
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39
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Farah JA, Cromie G, Davis L, Steiner WW, Smith GR. Activation of an alternative, rec12 (spo11)-independent pathway of fission yeast meiotic recombination in the absence of a DNA flap endonuclease. Genetics 2005; 171:1499-511. [PMID: 16118186 PMCID: PMC1456079 DOI: 10.1534/genetics.105.046821] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Accepted: 08/04/2005] [Indexed: 11/18/2022] Open
Abstract
Spo11 or a homologous protein appears to be essential for meiotic DNA double-strand break (DSB) formation and recombination in all organisms tested. We report here the first example of an alternative, mutationally activated pathway for meiotic recombination in the absence of Rec12, the Spo11 homolog of Schizosaccharomyces pombe. Rad2, a FEN-1 flap endonuclease homolog, is involved in processing Okazaki fragments. In its absence, meiotic recombination and proper segregation of chromosomes were restored in rec12Delta mutants to nearly wild-type levels. Although readily detectable in wild-type strains, meiosis-specific DSBs were undetectable in recombination-proficient rad2Delta rec12Delta strains. On the basis of the biochemical properties of Rad2, we propose that meiotic recombination by this alternative (Rec*) pathway can be initiated by non-DSB lesions, such as nicks and gaps, which accumulate during premeiotic DNA replication in the absence of Okazaki fragment processing. We compare the Rec* pathway to alternative pathways of homologous recombination in other organisms.
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Affiliation(s)
- Joseph A Farah
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 11200 Fairview Avenue North, Seattle, WA 98109-1024, USA
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40
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Abstract
Homologous recombination (HR) is required to promote both correct chromosome segregation and genetic variation during meiosis. For this to be successful recombination intermediates must be resolved to generate reciprocal exchanges or 'crossovers' between the homologous chromosomes (homologues) during the first meiotic division. Crossover recombination promotes faithful chromosome segregation by establishing connections (chiasmata) between the homologues, which help guide their proper bipolar alignment on the meiotic spindle. Recent studies of meiotic recombination in both the budding and fission yeasts have established that there are at least two pathways for generating crossovers. One pathway involves the resolution of fully ligated four-way DNA junctions [HJs (Holliday junctions)] by an as yet unidentified endonuclease. The second pathway appears to involve the cleavage of the precursors of ligated HJs, namely displacement (D) loops and unligated/nicked HJs, by the Mus81-Eme1/Mms4 endonuclease.
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41
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Current awareness on yeast. Yeast 2005. [DOI: 10.1002/yea.1168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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42
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Steiner WW, Smith GR. Natural meiotic recombination hot spots in the Schizosaccharomyces pombe genome successfully predicted from the simple sequence motif M26. Mol Cell Biol 2005; 25:9054-62. [PMID: 16199881 PMCID: PMC1265782 DOI: 10.1128/mcb.25.20.9054-9062.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 07/11/2005] [Accepted: 07/22/2005] [Indexed: 11/20/2022] Open
Abstract
The M26 hot spot of meiotic recombination in Schizosaccharomyces pombe is the eukaryotic hot spot most thoroughly investigated at the nucleotide level. The minimum sequence required for M26 activity was previously determined to be 5'-ATGACGT-3'. Originally identified by a mutant allele, ade6-M26, the M26 heptamer sequence occurs in the wild-type S. pombe genome approximately 300 times, but it has been unclear whether any of these are active hot spots. Recently, we showed that the M26 heptamer forms part of a larger consensus sequence, which is significantly more active than the heptamer alone. We used this expanded sequence as a guide to identify a smaller number of sites most likely to be active hot spots. Ten of the 15 sites tested showed meiotic DNA breaks, a hallmark of recombination hot spots, within 1 kb of the M26 sequence. Among those 10 sites, one occurred within a gene, cds1(+), and hot spot activity of this site was confirmed genetically. These results are, to our knowledge, the first demonstration in any organism of a simple, defined nucleotide sequence accurately predicting the locations of natural meiotic recombination hot spots. M26 may be the first example among a diverse group of simple sequences that determine the distribution, and hence predictability, of meiotic recombination hot spots in eukaryotic genomes.
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Affiliation(s)
- Walter W Steiner
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
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43
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Ellermeier C, Smith GR. Cohesins are required for meiotic DNA breakage and recombination in Schizosaccharomyces pombe. Proc Natl Acad Sci U S A 2005; 102:10952-7. [PMID: 16043696 PMCID: PMC1182449 DOI: 10.1073/pnas.0504805102] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In preparation for the unique segregation of homologs at the first meiotic division, chromosomes undergo dramatic changes. The meiosis-specific sister chromatid cohesins Rec8 and Rec11 of Schizosaccharomyces pombe are recruited around the time of premeiotic replication, and Rec10, a component of meiosis-specific linear elements, is subsequently added. Here we report that Rec10 is essential for meiosis-specific DNA breakage by Rec12 (Spo11 homolog) and for meiotic recombination. DNA breakage and recombination also depend on the Rec8 and Rec11 cohesins, strictly in some genomic intervals but less so in others. Thus, in addition to their previously recognized role in meiotic chromosome segregation, cohesins have a direct role, as do linear element components, in meiotic recombination by enabling double-strand DNA break formation by Rec12. Our results reveal a pathway, whose regulation is significantly different from that in the distantly related yeast Saccharomyces cerevisiae, for meiosis-specific chromosome differentiation and high-frequency recombination.
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Affiliation(s)
- Chad Ellermeier
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, A1-162, Seattle, WA 98109, USA
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44
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Farah JA, Cromie G, Steiner WW, Smith GR. A novel recombination pathway initiated by the Mre11/Rad50/Nbs1 complex eliminates palindromes during meiosis in Schizosaccharomyces pombe. Genetics 2005; 169:1261-74. [PMID: 15654094 PMCID: PMC1449568 DOI: 10.1534/genetics.104.037515] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA palindromes are rare in humans but are associated with meiosis-specific translocations. The conserved Mre11/Rad50/Nbs1 (MRN) complex is likely directly involved in processing palindromes through the homologous recombination pathway of DNA repair. Using the fission yeast Schizosaccharomyces pombe as a model system, we show that a 160-bp palindrome (M-pal) is a meiotic recombination hotspot and is preferentially eliminated by gene conversion. Importantly, this hotspot depends on the MRN complex for full activity and reveals a new pathway for generating meiotic DNA double-strand breaks (DSBs), separately from the Rec12 (ortholog of Spo11) pathway. We show that MRN-dependent DSBs are formed at or near the M-pal in vivo, and in contrast to the Rec12-dependent breaks, they appear early, during premeiotic replication. Analysis of mrn mutants indicates that the early DSBs are generated by the MRN nuclease activity, demonstrating the previously hypothesized MRN-dependent breakage of hairpins during replication. Our studies provide a genetic and physical basis for frequent translocations between palindromes in human meiosis and identify a conserved meiotic process that constantly selects against palindromes in eukaryotic genomes.
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Affiliation(s)
- Joseph A Farah
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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