1
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Ito M, Fujita Y, Shinohara A. Positive and negative regulators of RAD51/DMC1 in homologous recombination and DNA replication. DNA Repair (Amst) 2024; 134:103613. [PMID: 38142595 DOI: 10.1016/j.dnarep.2023.103613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/10/2023] [Accepted: 12/10/2023] [Indexed: 12/26/2023]
Abstract
RAD51 recombinase plays a central role in homologous recombination (HR) by forming a nucleoprotein filament on single-stranded DNA (ssDNA) to catalyze homology search and strand exchange between the ssDNA and a homologous double-stranded DNA (dsDNA). The catalytic activity of RAD51 assembled on ssDNA is critical for the DNA-homology-mediated repair of DNA double-strand breaks in somatic and meiotic cells and restarting stalled replication forks during DNA replication. The RAD51-ssDNA complex also plays a structural role in protecting the regressed/reversed replication fork. Two types of regulators control RAD51 filament formation, stability, and dynamics, namely positive regulators, including mediators, and negative regulators, so-called remodelers. The appropriate balance of action by the two regulators assures genome stability. This review describes the roles of positive and negative RAD51 regulators in HR and DNA replication and its meiosis-specific homolog DMC1 in meiotic recombination. We also provide future study directions for a comprehensive understanding of RAD51/DMC1-mediated regulation in maintaining and inheriting genome integrity.
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Affiliation(s)
- Masaru Ito
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Yurika Fujita
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
| | - Akira Shinohara
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
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2
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Lee W, Iwasaki H, Tsubouchi H, Li HW. Hop2-Mnd1 and Swi5-Sfr1 stimulate Dmc1 filament assembly using distinct mechanisms. Nucleic Acids Res 2023; 51:8550-8562. [PMID: 37395447 PMCID: PMC10484676 DOI: 10.1093/nar/gkad561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/12/2023] [Accepted: 06/20/2023] [Indexed: 07/04/2023] Open
Abstract
In meiosis, Dmc1 recombinase and the general recombinase Rad51 are responsible for pairing homologous chromosomes and exchanging strands. Fission yeast (Schizosaccharomyces pombe) Swi5-Sfr1 and Hop2-Mnd1 stimulate Dmc1-driven recombination, but the stimulation mechanism is unclear. Using single-molecule fluorescence resonance energy transfer (smFRET) and tethered particle motion (TPM) experiments, we showed that Hop2-Mnd1 and Swi5-Sfr1 individually enhance Dmc1 filament assembly on single-stranded DNA (ssDNA) and adding both proteins together allows further stimulation. FRET analysis showed that Hop2-Mnd1 enhances the binding rate of Dmc1 while Swi5-Sfr1 specifically reduces the dissociation rate during the nucleation, about 2-fold. In the presence of Hop2-Mnd1, the nucleation time of Dmc1 filaments shortens, and doubling the ss/double-stranded DNA (ss/dsDNA) junctions of DNA substrates reduces the nucleation times in half. Order of addition experiments confirmed that Hop2-Mnd1 binds on DNA to recruit and stimulate Dmc1 nucleation at the ss/dsDNA junction. Our studies directly support the molecular basis of how Hop2-Mnd1 and Swi5-Sfr1 act on different steps during the Dmc1 filament assembly. DNA binding of these accessory proteins and nucleation preferences of recombinases thus dictate how their regulation can take place.
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Affiliation(s)
- Wei Lee
- Department of Chemistry, National Taiwan University, Taiwan
| | - Hiroshi Iwasaki
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Hideo Tsubouchi
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Hung-Wen Li
- Department of Chemistry, National Taiwan University, Taiwan
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3
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Liang P, Lister K, Yates L, Argunhan B, Zhang X. Phosphoregulation of DNA repair via the Rad51 auxiliary factor Swi5-Sfr1. J Biol Chem 2023; 299:104929. [PMID: 37330173 PMCID: PMC10366545 DOI: 10.1016/j.jbc.2023.104929] [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] [Received: 03/09/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/19/2023] Open
Abstract
Homologous recombination (HR) is a major pathway for the repair of DNA double-strand breaks, the most severe form of DNA damage. The Rad51 protein is central to HR, but multiple auxiliary factors regulate its activity. The heterodimeric Swi5-Sfr1 complex is one such factor. It was previously shown that two sites within the intrinsically disordered domain of Sfr1 are critical for the interaction with Rad51. Here, we show that phosphorylation of five residues within this domain regulates the interaction of Swi5-Sfr1 with Rad51. Biochemical reconstitutions demonstrated that a phosphomimetic mutant version of Swi5-Sfr1 is defective in both the physical and functional interaction with Rad51. This translated to a defect in DNA repair, with the phosphomimetic mutant yeast strain phenocopying a previously established interaction mutant. Interestingly, a strain in which Sfr1 phosphorylation was blocked also displayed sensitivity to DNA damage. Taken together, we propose that controlled phosphorylation of Sfr1 is important for the role of Swi5-Sfr1 in promoting Rad51-dependent DNA repair.
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Affiliation(s)
- Pengtao Liang
- Section of Structural and Synthetic Biology, Faculty of Medicine, Imperial College London, London, UK
| | - Katie Lister
- Section of Structural and Synthetic Biology, Faculty of Medicine, Imperial College London, London, UK
| | - Luke Yates
- Section of Structural and Synthetic Biology, Faculty of Medicine, Imperial College London, London, UK
| | - Bilge Argunhan
- Section of Structural and Synthetic Biology, Faculty of Medicine, Imperial College London, London, UK.
| | - Xiaodong Zhang
- Section of Structural and Synthetic Biology, Faculty of Medicine, Imperial College London, London, UK.
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4
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Arcangioli B, Gangloff S. The Fission Yeast Mating-Type Switching Motto: "One-for-Two" and "Two-for-One". Microbiol Mol Biol Rev 2023; 87:e0000821. [PMID: 36629411 PMCID: PMC10029342 DOI: 10.1128/mmbr.00008-21] [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: 01/12/2023] Open
Abstract
Schizosaccharomyces pombe is an ascomycete fungus that divides by medial fission; it is thus commonly referred to as fission yeast, as opposed to the distantly related budding yeast Saccharomyces cerevisiae. The reproductive lifestyle of S. pombe relies on an efficient genetic sex determination system generating a 1:1 sex ratio and using alternating haploid/diploid phases in response to environmental conditions. In this review, we address how one haploid cell manages to generate two sister cells with opposite mating types, a prerequisite to conjugation and meiosis. This mating-type switching process depends on two highly efficient consecutive asymmetric cell divisions that rely on DNA replication, repair, and recombination as well as the structure and components of heterochromatin. We pay special attention to the intimate interplay between the genetic and epigenetic partners involved in this process to underscore the importance of basic research and its profound implication for a better understanding of chromatin biology.
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Affiliation(s)
- Benoît Arcangioli
- Genome Dynamics Unit, Genomes and Genetics Department, Pasteur Institute, Paris, France
| | - Serge Gangloff
- Genome Dynamics Unit, Genomes and Genetics Department, Pasteur Institute, Paris, France
- UMR3525, Genetics of Genomes, CNRS-Pasteur Institute, Paris, France
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5
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Disbennett WM, Hawk TM, Rollins PD, Nelakurti DD, Lucas BE, McPherson MT, Hylton HM, Petreaca RC. Genetic interaction of the histone chaperone hip1 + with double strand break repair genes in Schizosaccharomyces pombe. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000545. [PMID: 35622511 PMCID: PMC9005195 DOI: 10.17912/micropub.biology.000545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/22/2022] [Indexed: 11/06/2022]
Abstract
Schizosaccharomyces pombe hip1 + (human HIRA) is a histone chaperone and transcription factor involved in establishment of the centromeric chromatin and chromosome segregation, regulation of histone transcription, and cellular response to stress. We carried out a double mutant genetic screen of Δhip1 and mutations in double strand break repair pathway. We find that hip1 + functions after the MRN complex which initiates resection of blunt double strand break ends but before recruitment of the DNA damage repair machinery. Further, deletion of hip1 + partially suppresses sensitivity to DNA damaging agents of mutations in genes involved in Break Induced Replication (BIR), one mechanism of rescue of stalled or collapses replication forks ( rad51 + , cdc27 + ). Δhip1 also suppresses mutations in two checkpoint genes ( cds1 + , rad3 + ) on hydroxyurea a drug that stalls replication forks. Our results show that hip1 + forms complex interactions with the DNA double strand break repair genes and may be involved in facilitating communication between damage sensors and downstream factors.
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Affiliation(s)
| | - Tila M. Hawk
- James Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | - P. Daniel Rollins
- Molecular Genetics Undergraduate Program, The Ohio State University, Columbus, OH
| | - Devi D Nelakurti
- Biomedical Science Undergraduate Program, The Ohio State University Medical School, Columbus, OH
| | - Bailey E Lucas
- James Comprehensive Cancer Center, The Ohio State University, Columbus, OH
| | | | - Hannah M Hylton
- Biology Undergraduate Program, The Ohio State University, Marion, OH
| | - Ruben C Petreaca
- Department of Molecular Genetics, The Ohio State University, Marion, OH
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6
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Reitz D, Chan YL, Bishop DK. How strand exchange protein function benefits from ATP hydrolysis. Curr Opin Genet Dev 2021; 71:120-128. [PMID: 34343922 PMCID: PMC8671154 DOI: 10.1016/j.gde.2021.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/25/2022]
Abstract
Members of the RecA family of strand exchange proteins carry out the central reaction in homologous recombination. These proteins are DNA-dependent ATPases, although their ATPase activity is not required for the key functions of homology search and strand exchange. We review the literature on the role of the intrinsic ATPase activity of strand exchange proteins. We also discuss the role of ATP-hydrolysis-dependent motor proteins that serve as strand exchange accessory factors, with an emphasis on the eukaryotic Rad54 family of double strand DNA-specific translocases. The energy from ATP allows recombination events to progress from the strand exchange stage to subsequent stages. ATP hydrolysis also functions to corrects DNA binding errors, including particularly detrimental binding to double strand DNA.
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Affiliation(s)
- Diedre Reitz
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, USA
| | - Yuen-Ling Chan
- Department of Radiation and Cellular Oncology, University of Chicago, IL, USA
| | - Douglas K Bishop
- Department of Radiation and Cellular Oncology, University of Chicago, IL, USA; Department of Molecular Genetics and Cell Biology, University of Chicago, IL, USA.
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7
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Muraszko J, Kramarz K, Argunhan B, Ito K, Baranowska G, Kurokawa Y, Murayama Y, Tsubouchi H, Lambert S, Iwasaki H, Dziadkowiec D. Rrp1 translocase and ubiquitin ligase activities restrict the genome destabilising effects of Rad51 in fission yeast. Nucleic Acids Res 2021; 49:6832-6848. [PMID: 34157114 PMCID: PMC8266636 DOI: 10.1093/nar/gkab511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 05/27/2021] [Accepted: 06/06/2021] [Indexed: 11/20/2022] Open
Abstract
Rad51 is the key protein in homologous recombination that plays important roles during DNA replication and repair. Auxiliary factors regulate Rad51 activity to facilitate productive recombination, and prevent inappropriate, untimely or excessive events, which could lead to genome instability. Previous genetic analyses identified a function for Rrp1 (a member of the Rad5/16-like group of SWI2/SNF2 translocases) in modulating Rad51 function, shared with the Rad51 mediator Swi5-Sfr1 and the Srs2 anti-recombinase. Here, we show that Rrp1 overproduction alleviates the toxicity associated with excessive Rad51 levels in a manner dependent on Rrp1 ATPase domain. Purified Rrp1 binds to DNA and has a DNA-dependent ATPase activity. Importantly, Rrp1 directly interacts with Rad51 and removes it from double-stranded DNA, confirming that Rrp1 is a translocase capable of modulating Rad51 function. Rrp1 affects Rad51 binding at centromeres. Additionally, we demonstrate in vivo and in vitro that Rrp1 possesses E3 ubiquitin ligase activity with Rad51 as a substrate, suggesting that Rrp1 regulates Rad51 in a multi-tiered fashion.
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Affiliation(s)
| | - Karol Kramarz
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France.,Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Bilge Argunhan
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Kentaro Ito
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | | | - Yumiko Kurokawa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Yasuto Murayama
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Hideo Tsubouchi
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Sarah Lambert
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France.,Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Hiroshi Iwasaki
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan
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8
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Tsubouchi H, Argunhan B, Iwasaki H. Biochemical properties of fission yeast homologous recombination enzymes. Curr Opin Genet Dev 2021; 71:19-26. [PMID: 34246071 DOI: 10.1016/j.gde.2021.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/06/2021] [Accepted: 06/14/2021] [Indexed: 12/20/2022]
Abstract
Homologous recombination (HR) is a universal phenomenon conserved from viruses to humans. The mechanisms of HR are essentially the same in humans and simple unicellular eukaryotes like yeast. Two highly diverged yeast species, Saccharomyces cerevisiae and Schizosaccharomyces pombe, have proven exceptionally useful in understanding the fundamental mechanisms of eukaryotic HR by serving as a source for unique biological insights and also complementing each other. Here, we will review the features of S. pombe HR mechanisms in comparison to S. cerevisiae and other model organisms. Particular emphasis will be put on the biochemical characterization of HR mechanisms uncovered using S. pombe proteins.
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Affiliation(s)
- Hideo Tsubouchi
- Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan.
| | - Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan.
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9
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Argunhan B, Iwasaki H, Tsubouchi H. Post-translational modification of factors involved in homologous recombination. DNA Repair (Amst) 2021; 104:103114. [PMID: 34111757 DOI: 10.1016/j.dnarep.2021.103114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 02/04/2023]
Abstract
DNA is the molecule that stores the chemical instructions necessary for life and its stability is therefore of the utmost importance. Despite this, DNA is damaged by both exogenous and endogenous factors at an alarming frequency. The most severe type of DNA damage is a double-strand break (DSB), in which a scission occurs in both strands of the double helix, effectively dividing a single normal chromosome into two pathological chromosomes. Homologous recombination (HR) is a universal DSB repair mechanism that solves this problem by identifying another region of the genome that shares high sequence similarity with the DSB site and using it as a template for repair. Rad51 possess the enzymatic activity that is essential for this repair but several auxiliary factors are required for Rad51 to fulfil its function. It is becoming increasingly clear that many HR factors are subjected to post-translational modification. Here, we review what is known about how these modifications affect HR. We first focus on cases where there is experimental evidence to support a function for the modification, then discuss speculative cases where a function can be inferred. Finally, we contemplate why such modifications might be necessary.
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Affiliation(s)
- Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Hideo Tsubouchi
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan; School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
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10
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Afshar N, Argunhan B, Palihati M, Taniguchi G, Tsubouchi H, Iwasaki H. A novel motif of Rad51 serves as an interaction hub for recombination auxiliary factors. eLife 2021; 10:64131. [PMID: 33493431 PMCID: PMC7837696 DOI: 10.7554/elife.64131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 12/26/2020] [Indexed: 12/14/2022] Open
Abstract
Homologous recombination (HR) is essential for maintaining genome stability. Although Rad51 is the key protein that drives HR, multiple auxiliary factors interact with Rad51 to potentiate its activity. Here, we present an interdisciplinary characterization of the interactions between Rad51 and these factors. Through structural analysis, we identified an evolutionarily conserved acidic patch of Rad51. The neutralization of this patch completely abolished recombinational DNA repair due to defects in the recruitment of Rad51 to DNA damage sites. This acidic patch was found to be important for the interaction with Rad55-Rad57 and essential for the interaction with Rad52. Furthermore, biochemical reconstitutions demonstrated that neutralization of this acidic patch also impaired the interaction with Rad54, indicating that a single motif is important for the interaction with multiple auxiliary factors. We propose that this patch is a fundamental motif that facilitates interactions with auxiliary factors and is therefore essential for recombinational DNA repair.
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Affiliation(s)
- Negar Afshar
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Maierdan Palihati
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Goki Taniguchi
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Hideo Tsubouchi
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Hiroshi Iwasaki
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
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11
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Real-time tracking reveals catalytic roles for the two DNA binding sites of Rad51. Nat Commun 2020; 11:2950. [PMID: 32528002 PMCID: PMC7289862 DOI: 10.1038/s41467-020-16750-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 05/19/2020] [Indexed: 02/03/2023] Open
Abstract
During homologous recombination, Rad51 forms a nucleoprotein filament on single-stranded DNA to promote DNA strand exchange. This filament binds to double-stranded DNA (dsDNA), searches for homology, and promotes transfer of the complementary strand, producing a new heteroduplex. Strand exchange proceeds via two distinct three-strand intermediates, C1 and C2. C1 contains the intact donor dsDNA whereas C2 contains newly formed heteroduplex DNA. Here, we show that the conserved DNA binding motifs, loop 1 (L1) and loop 2 (L2) in site I of Rad51, play distinct roles in this process. L1 is involved in formation of the C1 complex whereas L2 mediates the C1–C2 transition, producing the heteroduplex. Another DNA binding motif, site II, serves as the DNA entry position for initial Rad51 filament formation, as well as for donor dsDNA incorporation. Our study provides a comprehensive molecular model for the catalytic process of strand exchange mediated by eukaryotic RecA-family recombinases. Rad51 drives DNA strand exchange, the central reaction in recombinational DNA repair. Two sites of Rad51 are responsible for DNA binding, but the function of these sites has proven elusive. Here, the authors employ real-time assays to reveal catalytic roles for the two DNA binding sites of Rad51.
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12
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Two auxiliary factors promote Dmc1-driven DNA strand exchange via stepwise mechanisms. Proc Natl Acad Sci U S A 2020; 117:12062-12070. [PMID: 32414915 DOI: 10.1073/pnas.1917419117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Homologous recombination (HR) is a universal mechanism operating in somatic and germ-line cells, where it contributes to the maintenance of genome stability and ensures the faithful distribution of genetic material, respectively. The ability to identify and exchange the strands of two homologous DNA molecules lies at the heart of HR and is mediated by RecA-family recombinases. Dmc1 is a meiosis-specific RecA homolog in eukaryotes, playing a predominant role in meiotic HR. However, Dmc1 cannot function without its two major auxiliary factor complexes, Swi5-Sfr1 and Hop2-Mnd1. Through biochemical reconstitutions, we demonstrate that Swi5-Sfr1 and Hop2-Mnd1 make unique contributions to stimulate Dmc1-driven strand exchange in a synergistic manner. Mechanistically, Swi5-Sfr1 promotes establishment of the Dmc1 nucleoprotein filament, whereas Hop2-Mnd1 defines a critical, rate-limiting step in initiating strand exchange. Following execution of this function, we propose that Swi5-Sfr1 then promotes strand exchange with Hop2-Mnd1. Thus, our findings elucidate distinct yet complementary roles of two auxiliary factors in Dmc1-driven strand exchange, providing mechanistic insights into some of the most critical steps in meiotic HR.
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13
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Argunhan B, Sakakura M, Afshar N, Kurihara M, Ito K, Maki T, Kanamaru S, Murayama Y, Tsubouchi H, Takahashi M, Takahashi H, Iwasaki H. Cooperative interactions facilitate stimulation of Rad51 by the Swi5-Sfr1 auxiliary factor complex. eLife 2020; 9:52566. [PMID: 32204793 PMCID: PMC7093153 DOI: 10.7554/elife.52566] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 02/13/2020] [Indexed: 01/26/2023] Open
Abstract
Although Rad51 is the key protein in homologous recombination (HR), a major DNA double-strand break repair pathway, several auxiliary factors interact with Rad51 to promote productive HR. We present an interdisciplinary characterization of the interaction between Rad51 and Swi5-Sfr1, a conserved auxiliary factor. Two distinct sites within the intrinsically disordered N-terminus of Sfr1 (Sfr1N) were found to cooperatively bind Rad51. Deletion of this domain impaired Rad51 stimulation in vitro and rendered cells sensitive to DNA damage. By contrast, amino acid-substitution mutants, which had comparable biochemical defects, could promote DNA repair, suggesting that Sfr1N has another role in addition to Rad51 binding. Unexpectedly, the DNA repair observed in these mutants was dependent on Rad55-Rad57, another auxiliary factor complex hitherto thought to function independently of Swi5-Sfr1. When combined with the finding that they form a higher-order complex, our results imply that Swi5-Sfr1 and Rad55-Rad57 can collaboratively stimulate Rad51 in Schizosaccharomyces pombe.
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Affiliation(s)
- Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Masayoshi Sakakura
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Negar Afshar
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Misato Kurihara
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Kentaro Ito
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Takahisa Maki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - Shuji Kanamaru
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Yasuto Murayama
- Center for Frontier Research, National Institute of Genetics, Shizuoka, Japan
| | - Hideo Tsubouchi
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Masayuki Takahashi
- School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Hideo Takahashi
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
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14
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Ekimoto T, Kokabu Y, Oroguchi T, Ikeguchi M. Combination of coarse-grained molecular dynamics simulations and small-angle X-ray scattering experiments. Biophys Physicobiol 2019; 16:377-390. [PMID: 31984192 PMCID: PMC6976007 DOI: 10.2142/biophysico.16.0_377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/11/2019] [Indexed: 12/01/2022] Open
Abstract
The combination of molecular dynamics (MD) simulations and small-angle X-ray scattering (SAXS), called the MD-SAXS method, is efficient for investigating protein dynamics. To overcome the time-scale limitation of all-atom MD simulations, coarse-grained (CG) representations are often utilized for biomolecular simulations. In this study, we propose a method to combine CG MD simulations with SAXS, termed the CG-MD-SAXS method. In the CG-MD-SAXS method, the scattering factors of CG particles for proteins and nucleic acids are evaluated using high-resolution structural data in the Protein Data Bank, and the excluded volume and the hydration shell are modeled using two adjustable parameters to incorporate solvent effects. To avoid overfitting, only the two parameters are adjusted for an entire structure ensemble. To verify the developed method, theoretical SAXS profiles for various proteins, DNA/RNA, and a protein-RNA complex are compared with both experimental profiles and theoretical profiles obtained by the all-atom representation. In the present study, we applied the CG-MD-SAXS method to the Swi5-Sfr1 complex and three types of nucleosomes to obtain reliable ensemble models consistent with the experimental SAXS data.
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Affiliation(s)
- Toru Ekimoto
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa 230-0045, Japan
| | - Yuichi Kokabu
- Bioscience Department, Mitsui Knowledge Industry Co., Ltd., Minato-ku, Tokyo 105-6215, Japan
| | - Tomotaka Oroguchi
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa 230-0045, Japan.,Department of Physics, Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Mitsunori Ikeguchi
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa 230-0045, Japan.,Medical Sciences Innovation Hub Program RIKEN, Yokohama, Kanagawa 230-0045, Japan
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15
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Keyamura K, Hishida T. Topological DNA-binding of structural maintenance of chromosomes-like RecN promotes DNA double-strand break repair in Escherichia coli. Commun Biol 2019; 2:413. [PMID: 31754643 PMCID: PMC6856136 DOI: 10.1038/s42003-019-0655-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 10/16/2019] [Indexed: 12/21/2022] Open
Abstract
Bacterial RecN, closely related to the structural maintenance of chromosomes (SMC) family of proteins, functions in the repair of DNA double-strand breaks (DSBs) by homologous recombination. Here we show that the purified Escherichia coli RecN protein topologically loads onto both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) that has a preference for ssDNA. RecN topologically bound to dsDNA slides off the end of linear dsDNA, but this is prevented by RecA nucleoprotein filaments on ssDNA, thereby allowing RecN to translocate to DSBs. Furthermore, we found that, once RecN is recruited onto ssDNA, it can topologically capture a second dsDNA substrate in an ATP-dependent manner, suggesting a role in synapsis. Indeed, RecN stimulates RecA-mediated D-loop formation and subsequent strand exchange activities. Our findings provide mechanistic insights into the recruitment of RecN to DSBs and sister chromatid interactions by RecN, both of which function in RecA-mediated DSB repair.
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Affiliation(s)
- Kenji Keyamura
- Department of Molecular Biology, Graduate School of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan
| | - Takashi Hishida
- Department of Molecular Biology, Graduate School of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan
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16
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Thon G, Maki T, Haber JE, Iwasaki H. Mating-type switching by homology-directed recombinational repair: a matter of choice. Curr Genet 2018; 65:351-362. [PMID: 30382337 PMCID: PMC6420890 DOI: 10.1007/s00294-018-0900-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/13/2018] [Accepted: 10/24/2018] [Indexed: 12/14/2022]
Abstract
In eukaryotes, all DNA transactions happen in the context of chromatin that often takes part in regulatory mechanisms. In particular, chromatin structure can regulate exchanges of DNA occurring through homologous recombination. Few systems have provided as detailed a view on this phenomenon as mating-type switching in yeast. Mating-type switching entails the choice of a template for the gene conversions of the expressed mating-type locus. In the fission yeast Schizosaccharomyces pombe, correct template choice requires two competing small recombination enhancers, SRE2 and SRE3, that function in the context of heterochromatin. These two enhancers act with the Swi2/Swi5 recombination accessory complex to initiate strand exchange in a cell-type-specific manner, from SRE2 in M cells and SRE3 in P cells. New research indicates that the Set1C complex, responsible for H3K4 methylation, and the Brl2 ubiquitin ligase, that catalyzes H2BK119 ubiquitylation, participate in the cell-type-specific selection of SRE2 or SRE3. Here, we review these findings, compare donor preference in S. pombe to the distantly related budding yeast Saccharomyces cerevisiae, and contrast the positive effects of heterochromatin on the donor selection process with other situations, where heterochromatin represses recombination.
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Affiliation(s)
- Geneviève Thon
- Department of Biology, BioCenter, University of Copenhagen, Copenhagen, Denmark.
| | - Takahisa Maki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, 02453, USA
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,Department of Life Science and Technology, School of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan
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17
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Swi5-Sfr1 stimulates Rad51 recombinase filament assembly by modulating Rad51 dissociation. Proc Natl Acad Sci U S A 2018; 115:E10059-E10068. [PMID: 30297419 DOI: 10.1073/pnas.1812753115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic Rad51 protein is essential for homologous-recombination repair of DNA double-strand breaks. Rad51 recombinases first assemble onto single-stranded DNA to form a nucleoprotein filament, required for function in homology pairing and strand exchange. This filament assembly is the first regulation step in homologous recombination. Rad51 nucleation is kinetically slow, and several accessory factors have been identified to regulate this step. Swi5-Sfr1 (S5S1) stimulates Rad51-mediated homologous recombination by stabilizing Rad51 nucleoprotein filaments, but the mechanism of stabilization is unclear. We used single-molecule tethered particle motion experiments to show that mouse S5S1 (mS5S1) efficiently stimulates mouse RAD51 (mRAD51) nucleus formation and inhibits mRAD51 dissociation from filaments. We also used single-molecule fluorescence resonance energy transfer experiments to show that mS5S1 promotes stable nucleus formation by specifically preventing mRAD51 dissociation. This leads to a reduction of nucleation size from three mRAD51 to two mRAD51 molecules in the presence of mS5S1. Compared with mRAD51, fission yeast Rad51 (SpRad51) exhibits fast nucleation but quickly dissociates from the filament. SpS5S1 specifically reduces SpRad51 disassembly to maintain a stable filament. These results clearly demonstrate the conserved function of S5S1 by primarily stabilizing Rad51 on DNA, allowing both the formation of the stable nucleus and the maintenance of filament length.
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18
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New insights into donor directionality of mating-type switching in Schizosaccharomyces pombe. PLoS Genet 2018; 14:e1007424. [PMID: 29852001 PMCID: PMC6007933 DOI: 10.1371/journal.pgen.1007424] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/19/2018] [Accepted: 05/17/2018] [Indexed: 11/29/2022] Open
Abstract
Mating-type switching in Schizosaccharomyces pombe entails programmed gene conversion events regulated by DNA replication, heterochromatin, and the HP1-like chromodomain protein Swi6. The whole mechanism remains to be fully understood. Using a gene deletion library, we screened ~ 3400 mutants for defects in the donor selection step where a heterochromatic locus, mat2-P or mat3-M, is chosen to convert the expressed mat1 locus. By measuring the biases in mat1 content that result from faulty directionality, we identified in total 20 factors required for donor selection. Unexpectedly, these included the histone H3 lysine 4 (H3K4) methyltransferase complex subunits Set1, Swd1, Swd2, Swd3, Spf1 and Ash2, the BRE1-like ubiquitin ligase Brl2 and the Elongator complex subunit Elp6. The mutant defects were investigated in strains with reversed donor loci (mat2-M mat3-P) or when the SRE2 and SRE3 recombination enhancers, adjacent to the donors, were deleted or transposed. Mutants in Set1C, Brl2 or Elp6 altered balanced donor usage away from mat2 and the SRE2 enhancer, towards mat3 and the SRE3 enhancer. The defects in these mutants were qualitatively similar to heterochromatin mutants lacking Swi6, the NAD+-dependent histone deacetylase Sir2, or the Clr4, Raf1 or Rik1 subunits of the histone H3 lysine 9 (H3K9) methyltransferase complex, albeit not as extreme. Other mutants showed clonal biases in switching. This was the case for mutants in the NAD+-independent deacetylase complex subunits Clr1, Clr2 and Clr3, the casein kinase CK2 subunit Ckb1, the ubiquitin ligase component Pof3, and the CENP-B homologue Cbp1, as well as for double mutants lacking Swi6 and Brl2, Pof3, or Cbp1. Thus, we propose that Set1C cooperates with Swi6 and heterochromatin to direct donor choice to mat2-P in M cells, perhaps by inhibiting the SRE3 recombination enhancer, and that in the absence of Swi6 other factors are still capable of imposing biases to donor choice. Effects of chromatin structure on recombination can be studied in the fission yeast S. pombe where two heterochromatic loci, mat2 and mat3, are chosen in a cell-type specific manner to convert the expressed mat1 locus and switch the yeast mating-type. The system has previously revealed the determining role of heterochromatin, histone H3K9 methylation and HP1 family protein Swi6, in donor selection. Here, we find that other chromatin modifiers and protein complexes, including components of the histone H3K4 methyltransferase complex Set1C, the histone H2B ubiquitin ligase HULC and Elongator, also participate in donor selection. Our findings open up new research paths to study mating-type switching in fission yeast and the roles of these complexes in recombination.
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19
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Murayama Y, Samora CP, Kurokawa Y, Iwasaki H, Uhlmann F. Establishment of DNA-DNA Interactions by the Cohesin Ring. Cell 2018; 172:465-477.e15. [PMID: 29358048 PMCID: PMC5786502 DOI: 10.1016/j.cell.2017.12.021] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/12/2017] [Accepted: 12/16/2017] [Indexed: 01/14/2023]
Abstract
The ring-shaped structural maintenance of chromosome (SMC) complexes are multi-subunit ATPases that topologically encircle DNA. SMC rings make vital contributions to numerous chromosomal functions, including mitotic chromosome condensation, sister chromatid cohesion, DNA repair, and transcriptional regulation. They are thought to do so by establishing interactions between more than one DNA. Here, we demonstrate DNA-DNA tethering by the purified fission yeast cohesin complex. DNA-bound cohesin efficiently and topologically captures a second DNA, but only if that is single-stranded DNA (ssDNA). Like initial double-stranded DNA (dsDNA) embrace, second ssDNA capture is ATP-dependent, and it strictly requires the cohesin loader complex. Second-ssDNA capture is relatively labile but is converted into stable dsDNA-dsDNA cohesion through DNA synthesis. Our study illustrates second-DNA capture by an SMC complex and provides a molecular model for the establishment of sister chromatid cohesion.
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Affiliation(s)
- Yasuto Murayama
- Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
| | - Catarina P Samora
- Chromosome Segregation Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Yumiko Kurokawa
- Education Academy of Computational Life Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Frank Uhlmann
- Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan; Chromosome Segregation Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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20
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Ito K, Murayama Y, Takahashi M, Iwasaki H. Two three-strand intermediates are processed during Rad51-driven DNA strand exchange. Nat Struct Mol Biol 2017; 25:29-36. [PMID: 29323270 DOI: 10.1038/s41594-017-0002-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/31/2017] [Indexed: 11/09/2022]
Abstract
During homologous recombination, Rad51 forms a nucleoprotein filament with single-stranded DNA (ssDNA) that undergoes strand exchange with homologous double-stranded DNA (dsDNA). Here, we use real-time analysis to show that strand exchange by fission yeast Rad51 proceeds via two distinct three-strand intermediates, C1 and C2. Both intermediates contain Rad51, but whereas the donor duplex remains intact in C1, the ssDNA strand is intertwined with the complementary strand of the donor duplex in C2. Swi5-Sfr1, an evolutionarily conserved recombination activator, facilitates the C1-C2 transition and subsequent ssDNA release from C2 to complete strand exchange in an ATP-hydrolysis-dependent manner. In contrast, Ca2+, which activates the Rad51 filament by curbing ATP hydrolysis, facilitates the C1-C2 transition but does not promote strand exchange. These results reveal that Swi5-Sfr1 and Ca2+ have different activation modes in the late synaptic phase, despite their common function in stabilizing the presynaptic filament.
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Affiliation(s)
- Kentaro Ito
- School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan
| | - Yasuto Murayama
- School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.,National Institute of Genetics, Shizuoka, Japan
| | - Masayuki Takahashi
- School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan
| | - Hiroshi Iwasaki
- School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan. .,Institute of Innovative Research, Tokyo Institute of Technology, Tokyo, Japan.
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21
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Sanchez A, Gadaleta MC, Limbo O, Russell P. Lingering single-strand breaks trigger Rad51-independent homology-directed repair of collapsed replication forks in the polynucleotide kinase/phosphatase mutant of fission yeast. PLoS Genet 2017; 13:e1007013. [PMID: 28922417 PMCID: PMC5626526 DOI: 10.1371/journal.pgen.1007013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 10/03/2017] [Accepted: 09/08/2017] [Indexed: 11/19/2022] Open
Abstract
The DNA repair enzyme polynucleotide kinase/phosphatase (PNKP) protects genome integrity by restoring ligatable 5'-phosphate and 3'-hydroxyl termini at single-strand breaks (SSBs). In humans, PNKP mutations underlie the neurological disease known as MCSZ, but these individuals are not predisposed for cancer, implying effective alternative repair pathways in dividing cells. Homology-directed repair (HDR) of collapsed replication forks was proposed to repair SSBs in PNKP-deficient cells, but the critical HDR protein Rad51 is not required in PNKP-null (pnk1Δ) cells of Schizosaccharomyces pombe. Here, we report that pnk1Δ cells have enhanced requirements for Rad3 (ATR/Mec1) and Chk1 checkpoint kinases, and the multi-BRCT domain protein Brc1 that binds phospho-histone H2A (γH2A) at damaged replication forks. The viability of pnk1Δ cells depends on Mre11 and Ctp1 (CtIP/Sae2) double-strand break (DSB) resection proteins, Rad52 DNA strand annealing protein, Mus81-Eme1 Holliday junction resolvase, and Rqh1 (BLM/WRN/Sgs1) DNA helicase. Coupled with increased sister chromatid recombination and Rad52 repair foci in pnk1Δ cells, these findings indicate that lingering SSBs in pnk1Δ cells trigger Rad51-independent homology-directed repair of collapsed replication forks. From these data, we propose models for HDR-mediated tolerance of persistent SSBs with 3' phosphate in pnk1Δ cells.
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Affiliation(s)
- Arancha Sanchez
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Mariana C. Gadaleta
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Oliver Limbo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Paul Russell
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
- * E-mail:
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22
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Argunhan B, Murayama Y, Iwasaki H. The differentiated and conserved roles of Swi5-Sfr1 in homologous recombination. FEBS Lett 2017; 591:2035-2047. [PMID: 28423184 PMCID: PMC5573924 DOI: 10.1002/1873-3468.12656] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 11/13/2022]
Abstract
Homologous recombination (HR) is the process whereby two DNA molecules that share high sequence similarity are able to recombine to generate hybrid DNA molecules. Throughout evolution, the ability of HR to identify highly similar DNA sequences has been adopted for numerous biological phenomena including DNA repair, meiosis, telomere maintenance, ribosomal DNA amplification and immunological diversity. Although Rad51 and Dmc1 are the key proteins that promote HR in mitotic and meiotic cells, respectively, accessory proteins that allow Rad51 and Dmc1 to effectively fulfil their functions have been identified in all examined model systems. In this Review, we discuss the roles of the highly conserved Swi5‐Sfr1 accessory complex in yeast, mice and humans, and explore similarities and differences between these species.
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Affiliation(s)
- Bilge Argunhan
- Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Yasuto Murayama
- Institute of Innovative Research, Tokyo Institute of Technology, Japan
| | - Hiroshi Iwasaki
- Institute of Innovative Research, Tokyo Institute of Technology, Japan
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23
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Dbl2 Regulates Rad51 and DNA Joint Molecule Metabolism to Ensure Proper Meiotic Chromosome Segregation. PLoS Genet 2016; 12:e1006102. [PMID: 27304859 PMCID: PMC4909299 DOI: 10.1371/journal.pgen.1006102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 05/12/2016] [Indexed: 11/19/2022] Open
Abstract
To identify new proteins required for faithful meiotic chromosome segregation, we screened a Schizosaccharomyces pombe deletion mutant library and found that deletion of the dbl2 gene led to missegregation of chromosomes during meiosis. Analyses of both live and fixed cells showed that dbl2Δ mutant cells frequently failed to segregate homologous chromosomes to opposite poles during meiosis I. Removing Rec12 (Spo11 homolog) to eliminate meiotic DNA double-strand breaks (DSBs) suppressed the segregation defect in dbl2Δ cells, indicating that Dbl2 acts after the initiation of meiotic recombination. Analyses of DSBs and Holliday junctions revealed no significant defect in their formation or processing in dbl2Δ mutant cells, although some Rec12-dependent DNA joint molecules persisted late in meiosis. Failure to segregate chromosomes in the absence of Dbl2 correlated with persistent Rad51 foci, and deletion of rad51 or genes encoding Rad51 mediators also suppressed the segregation defect of dbl2Δ. Formation of foci of Fbh1, an F-box helicase that efficiently dismantles Rad51-DNA filaments, was impaired in dbl2Δ cells. Our results suggest that Dbl2 is a novel regulator of Fbh1 and thereby Rad51-dependent DSB repair required for proper meiotic chromosome segregation and viable sex cell formation. The wide conservation of these proteins suggests that our results apply to many species. Meiosis produces haploid gametes from diploid precursor cells. This reduction of chromosome number is achieved by two successive divisions after only a single round of DNA replication. To identify novel regulators of meiosis, we screened a library of fission yeast deletion mutants and found that deletion of the dbl2 gene led to missegregation of chromosomes during meiosis. Analysis of live dbl2Δ cells by fluorescence microscopy showed that chromosomes frequently failed to segregate during the first meiotic division. Further cytological and biochemical analyses revealed that this segregation defect is due to persistent intermediates of DNA double-strand break repair, also called DNA joint molecules. Our results indicate that Dbl2 is required for formation of Fbh1 DNA helicase foci at the sites of DNA double-strand break repair in order to process DNA joint molecules and allow segregation of chromosomes during meiotic divisions. Our bioinformatics searches revealed that Dbl2 is highly conserved in fungi, animals and plants, suggesting that Dbl2 plays a similar role in other organisms–the formation of viable sex cells and healthy progeny.
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24
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Abstract
Homology search and DNA strand-exchange reactions are central to homologous recombination in meiosis. During meiosis, these processes are regulated such that the probability of choosing a homolog chromatid as recombination partner is enhanced relative to that of choosing a sister chromatid. This regulatory process occurs as homologous chromosomes pair in preparation for assembly of the synaptonemal complex. Two strand-exchange proteins, Rad51 and Dmc1, cooperate in regulated homology search and strand exchange in most organisms. Here, we summarize studies on the properties of these two proteins and their accessory factors. In addition, we review current models for the assembly of meiotic strand-exchange complexes and the possible mechanisms through which the interhomolog bias of recombination partner choice is achieved.
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Affiliation(s)
- M Scott Brown
- Department of Radiation and Cellular Oncology, and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
| | - Douglas K Bishop
- Department of Radiation and Cellular Oncology, and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
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25
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Abstract
Homologous DNA pairing and strand exchange are at the core of homologous recombination. These reactions are promoted by a DNA-strand-exchange protein assembled into a nucleoprotein filament comprising the DNA-pairing protein, ATP, and single-stranded DNA. The catalytic activity of this molecular machine depends on control of its dynamic instability by accessory factors. Here we discuss proteins known as recombination mediators that facilitate formation and functional activation of the DNA-strand-exchange protein filament. Although the basics of homologous pairing and DNA-strand exchange are highly conserved in evolution, differences in mediator function are required to cope with differences in how single-stranded DNA is packaged by the single-stranded DNA-binding protein in different species, and the biochemical details of how the different DNA-strand-exchange proteins nucleate and extend into a nucleoprotein filament. The set of (potential) mediator proteins has apparently expanded greatly in evolution, raising interesting questions about the need for additional control and coordination of homologous recombination in more complex organisms.
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Affiliation(s)
- Alex Zelensky
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
| | - Roland Kanaar
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands Department of Radiation Oncology, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
| | - Claire Wyman
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands Department of Radiation Oncology, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
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26
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Tsutsui Y, Kurokawa Y, Ito K, Siddique MSP, Kawano Y, Yamao F, Iwasaki H. Multiple regulation of Rad51-mediated homologous recombination by fission yeast Fbh1. PLoS Genet 2014; 10:e1004542. [PMID: 25165823 PMCID: PMC4148199 DOI: 10.1371/journal.pgen.1004542] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 06/16/2014] [Indexed: 11/18/2022] Open
Abstract
Fbh1, an F-box helicase related to bacterial UvrD, has been proposed to modulate homologous recombination in fission yeast. We provide several lines of evidence for such modulation. Fbh1, but not the related helicases Srs2 and Rqh1, suppressed the formation of crossover recombinants from single HO-induced DNA double-strand breaks. Purified Fbh1 in complex with Skp1 (Fbh1-Skp1 complex) inhibited Rad51-driven DNA strand exchange by disrupting Rad51 nucleoprotein filaments in an ATP-dependent manner; this disruption was alleviated by the Swi5-Sfr1 complex, an auxiliary activator of Rad51. In addition, the reconstituted SCFFbh1 complex, composed of purified Fbh1-Skp1 and Pcu1-Rbx1, displayed ubiquitin-ligase E3 activity toward Rad51. Furthermore, Fbh1 reduced the protein level of Rad51 in stationary phase in an F-box-dependent, but not in a helicase domain-independent manner. These results suggest that Fbh1 negatively regulates Rad51-mediated homologous recombination via its two putative, unrelated activities, namely DNA unwinding/translocation and ubiquitin ligation. In addition to its anti-recombinase activity, we tentatively suggest that Fbh1 might also have a pro-recombination role in vivo, because the Fbh1-Skp1 complex stimulated Rad51-mediated strand exchange in vitro after strand exchange had been initiated. Homologous recombination is required for repairing DNA double-strand breaks (DSBs), which are induced by exogenous factors such as DNA damaging agents or by endogenous factors such as collapse of DNA replication fork in mitotic cells. If improperly processed, DSBs could lead to chromosome rearrangement, cell death, or tumorigenesis in mammals, and thus HR is strictly controlled at several steps, including Rad51 recombinase-driven DNA strand exchange reaction. Specifically, DNA helicases have been shown to be important for suppression of inappropriate recombination events. In this study, we analyzed one such DNA helicase, fission yeast Fbh1. We used an in vivo single-DSB repair assay to show that Fbh1 suppresses crossover formation between homologous chromosomes. Next, we obtained in vitro evidence that Fbh1 acts as an inhibitor of the strand-exchange reaction in the absence of Swi5-Sfr1, but stimulates the reaction after it starts. Furthermore, we found that SCFFbh1 has ubiquitin-ligase activity toward Rad51 in vitro and that Fbh1 regulates the protein level of Rad51 in the stationary phase. These results suggest Fbh1 regulates Rad51-mediated homologous recombination by its seemingly-unrelated two activities, DNA helicase/translocase and ubiquitin ligase.
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Affiliation(s)
- Yasuhiro Tsutsui
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
- * E-mail: (YT); (HI)
| | - Yumiko Kurokawa
- Education Academy of Computational Life Science, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Kentaro Ito
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Md. Shahjahan P. Siddique
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Yumiko Kawano
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
| | - Fumiaki Yamao
- International Institute for Advanced Studies, Kizugawa, Kyoto, Japan
| | - Hiroshi Iwasaki
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
- * E-mail: (YT); (HI)
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27
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Liu Y, Gaines WA, Callender T, Busygina V, Oke A, Sung P, Fung JC, Hollingsworth NM. Down-regulation of Rad51 activity during meiosis in yeast prevents competition with Dmc1 for repair of double-strand breaks. PLoS Genet 2014; 10:e1004005. [PMID: 24465215 PMCID: PMC3900393 DOI: 10.1371/journal.pgen.1004005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 10/22/2013] [Indexed: 11/18/2022] Open
Abstract
Interhomolog recombination plays a critical role in promoting proper meiotic chromosome segregation but a mechanistic understanding of this process is far from complete. In vegetative cells, Rad51 is a highly conserved recombinase that exhibits a preference for repairing double strand breaks (DSBs) using sister chromatids, in contrast to the conserved, meiosis-specific recombinase, Dmc1, which preferentially repairs programmed DSBs using homologs. Despite the different preferences for repair templates, both Rad51 and Dmc1 are required for interhomolog recombination during meiosis. This paradox has recently been explained by the finding that Rad51 protein, but not its strand exchange activity, promotes Dmc1 function in budding yeast. Rad51 activity is inhibited in dmc1Δ mutants, where the failure to repair meiotic DSBs triggers the meiotic recombination checkpoint, resulting in prophase arrest. The question remains whether inhibition of Rad51 activity is important during wild-type meiosis, or whether inactivation of Rad51 occurs only as a result of the absence of DMC1 or checkpoint activation. This work shows that strains in which mechanisms that down-regulate Rad51 activity are removed exhibit reduced numbers of interhomolog crossovers and noncrossovers. A hypomorphic mutant, dmc1-T159A, makes less stable presynaptic filaments but is still able to mediate strand exchange and interact with accessory factors. Combining dmc1-T159A with up-regulated Rad51 activity reduces interhomolog recombination and spore viability, while increasing intersister joint molecule formation. These results support the idea that down-regulation of Rad51 activity is important during meiosis to prevent Rad51 from competing with Dmc1 for repair of meiotic DSBs.
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Affiliation(s)
- Yan Liu
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - William A. Gaines
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Tracy Callender
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Valeria Busygina
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ashwini Oke
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Jennifer C. Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Nancy M. Hollingsworth
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
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Murayama Y, Kurokawa Y, Tsutsui Y, Iwasaki H. Dual regulation of Dmc1-driven DNA strand exchange by Swi5-Sfr1 activation and Rad22 inhibition. Genes Dev 2013; 27:2299-304. [PMID: 24186976 PMCID: PMC3828516 DOI: 10.1101/gad.218693.113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Meiotic recombination requires two key recombinases: the ubiquitously expressed Rad51 and the meiosis-specific Dmc1. Rad52 and its fission yeast ortholog, Rad22, are mediators that help load Rad51 onto ssDNA coated with replication protein A (RPA). Here, Iwasaki and colleagues reveal how the Swi5–Sfr1 complex functions as both a mediator (loading DMC1 onto ssDNA) and an activator (stimulating Dmc1-driven strand exchange). In contrast, Rad22 inhibits Dmc1 by competing for binding to RPA-coated ssDNA. This study thus provides a novel regulatory mechanism for meiotic recombination. Both ubiquitously expressed Rad51 and meiosis-specific Dmc1 are required for crossover production during meiotic recombination. The budding yeast Rad52 and its fission yeast ortholog, Rad22, are “mediators;” i.e., they help load Rad51 onto ssDNA coated with replication protein A (RPA). Here we show that the Swi5–Sfr1 complex from fission yeast is both a mediator that loads Dmc1 onto ssDNA and a direct “activator” of DNA strand exchange by Dmc1. In stark contrast, Rad22 inhibits Dmc1 action by competing for its binding to RPA-coated ssDNA. Thus, Rad22 plays dual roles in regulating meiotic recombination: activating Rad51 and inhibiting Dmc1.
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Affiliation(s)
- Yasuto Murayama
- Department of Biological Sciences, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
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29
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Fornander LH, Renodon-Cornière A, Kuwabara N, Ito K, Tsutsui Y, Shimizu T, Iwasaki H, Nordén B, Takahashi M. Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament. Nucleic Acids Res 2013; 42:2358-65. [PMID: 24304898 PMCID: PMC3936755 DOI: 10.1093/nar/gkt1257] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.
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Affiliation(s)
- Louise H Fornander
- Department of Chemical and Biological Engineering, Chalmers University of Technology, S-41296 Gothenburg, Sweden, Research Unit FRE3478, Centre National de la Recherche Scientifique & University of Nantes, F-44322 Nantes cedex 3, France, Graduate School of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan, Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, KEK, Tsukuba, 305-0801, Japan and Department of Life Science, Graduate School of Bioscience & Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
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30
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Saikusa K, Kuwabara N, Kokabu Y, Inoue Y, Sato M, Iwasaki H, Shimizu T, Ikeguchi M, Akashi S. Characterisation of an intrinsically disordered protein complex of Swi5-Sfr1 by ion mobility mass spectrometry and small-angle X-ray scattering. Analyst 2013; 138:1441-9. [PMID: 23324799 DOI: 10.1039/c2an35878f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
It is now recognized that intrinsically disordered proteins (IDPs) play important roles as hubs in intracellular networks, and their structural characterisation is of significance. However, due to their highly dynamic features, it is challenging to investigate the structures of IDPs solely by conventional methods. In the present study, we demonstrate a novel method to characterise protein complexes using electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) in combination with small-angle X-ray scattering (SAXS). This method enables structural characterisation even of proteins that have difficulties in crystallisation. With this method, we have characterised the Schizosaccharomyces pombe Swi5-Sfr1 complex, which is expected to have a long disordered region at the N-terminal portion of Sfr1. ESI-IM-MS analysis of the Swi5-Sfr1 complex revealed that its experimental collision cross-section (CCS) had a wide distribution, and the CCS values of the most dominant ions were ∼56% of the theoretically calculated value based on the SAXS low-resolution model, suggesting a significant size reduction in the gas phase. The present study demonstrates that the newly developed method for calculation of the theoretical CCSs of the SAXS low-resolution models of proteins allows accurate evaluation of the experimental CCS values of IDPs provided by ESI-IM-MS by comparing with the low-resolution solution structures. Furthermore, it was revealed that the combination of ESI-IM-MS and SAXS is a promising method for structural characterisation of protein complexes that are unable to crystallise.
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Affiliation(s)
- Kazumi Saikusa
- Graduate School of Nanobioscience, Yokohama City University, Yokohama, Kanagawa 230-0045, Japan
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31
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Jakočiūnas T, Holm LR, Verhein-Hansen J, Trusina A, Thon G. Two portable recombination enhancers direct donor choice in fission yeast heterochromatin. PLoS Genet 2013; 9:e1003762. [PMID: 24204285 PMCID: PMC3812072 DOI: 10.1371/journal.pgen.1003762] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/18/2013] [Indexed: 01/06/2023] Open
Abstract
Mating-type switching in fission yeast results from gene conversions of the active mat1 locus by heterochromatic donors. mat1 is preferentially converted by mat2-P in M cells and by mat3-M in P cells. Here, we report that donor choice is governed by two portable recombination enhancers capable of promoting use of their adjacent cassette even when they are transposed to an ectopic location within the mat2-mat3 heterochromatic domain. Cells whose silent cassettes are swapped to mat2-M mat3-P switch mating-type poorly due to a defect in directionality but cells whose recombination enhancers were transposed together with the cassette contents switched like wild type. Trans-acting mutations that impair directionality affected the wild-type and swapped cassettes in identical ways when the recombination enhancers were transposed together with their cognate cassette, showing essential regulatory steps occur through the recombination enhancers. Our observations lead to a model where heterochromatin biases competitions between the two recombination enhancers to achieve directionality. The state of chromatin, heterochromatin or euchromatin, affects homologous recombination in eukaryotes. We study mating-type switching in fission yeast to learn how recombination is regulated in heterochromatin. Fission yeast exists as two mating-types, P or M, determined by the allele present at the expressed mat1 locus. Genetic information for the P and M mating-types is stored in two silent heterochromatic cassettes, mat2-P and mat3-M. Cells can switch mating-type by a replication-coupled recombination event where one of the silent cassettes is used as donor to convert mat1. Mating-type switching occurs in a directional manner where mat2-P is a preferred donor in M cells and mat3-M is preferred in P cells. In this study, we investigated factors responsible for these directed recombination events. We found that two portable recombination enhancers within the heterochromatic region compete with each other and direct recombination in a cell-type specific manner. We also found that heterochromatin plays an important role in directionality by biasing competitions between the two enhancers. Our findings suggest a new model for directed recombination in a heterochromatic domain and open the field for further studies of recombination regulation in other chromatin contexts.
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Affiliation(s)
- Tadas Jakočiūnas
- Department of Biology, University of Copenhagen, BioCenter, Copenhagen, Denmark
| | - Lærke Rebekka Holm
- Department of Biology, University of Copenhagen, BioCenter, Copenhagen, Denmark
| | | | - Ala Trusina
- Department of Biology, University of Copenhagen, BioCenter, Copenhagen, Denmark
| | - Geneviève Thon
- Department of Biology, University of Copenhagen, BioCenter, Copenhagen, Denmark
- * E-mail:
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32
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Su GC, Chung CI, Liao CY, Lin SW, Tsai CT, Huang T, Li HW, Chi P. Enhancement of ADP release from the RAD51 presynaptic filament by the SWI5-SFR1 complex. Nucleic Acids Res 2013; 42:349-58. [PMID: 24078249 PMCID: PMC3874192 DOI: 10.1093/nar/gkt879] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Homologous recombination catalyzed by the RAD51 recombinase eliminates deleterious DNA lesions from the genome. In the presence of ATP, RAD51 forms a nucleoprotein filament on single-stranded DNA, termed the presynaptic filament, to initiate homologous recombination-mediated DNA double-strand break repair. The SWI5-SFR1 complex stabilizes the presynaptic filament and enhances its ability to mediate the homologous DNA pairing reaction. Here we characterize the RAD51 presynaptic filament stabilization function of the SWI5-SFR1 complex using optical tweezers. Biochemical experiments reveal that SWI5-SFR1 enhances ATP hydrolysis by single-stranded DNA-bound RAD51. Importantly, we show that SWI5-SFR1 acts by facilitating the release of ADP from the presynaptic filament. Our results thus provide mechanistic understanding of the function of SWI5-SFR1 in RAD51-mediated DNA recombination.
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Affiliation(s)
- Guan-Chin Su
- Institute of Biochemical Sciences, National Taiwan University, NO. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 115, Taiwan and Department of Chemistry, National Taiwan University, NO. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
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33
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Chen H, Lisby M, Symington LS. RPA coordinates DNA end resection and prevents formation of DNA hairpins. Mol Cell 2013; 50:589-600. [PMID: 23706822 DOI: 10.1016/j.molcel.2013.04.032] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 03/14/2013] [Accepted: 04/12/2013] [Indexed: 11/29/2022]
Abstract
Replication protein A (RPA) is an essential eukaryotic single-stranded DNA binding protein with a central role in DNA metabolism. RPA directly participates in DNA double-strand break repair by stimulating 5'-3' end resection by the Sgs1/BLM helicase and Dna2 endonuclease in vitro. Here we investigated the role of RPA in end resection in vivo, using a heat-inducible degron system that allows rapid conditional depletion of RPA in Saccharomyces cerevisiae. We found that RPA depletion eliminated both the Sgs1-Dna2- and Exo1-dependent extensive resection pathways and synergized with mre11Δ to prevent end resection. The short single-stranded DNA tails formed in the absence of RPA were unstable due to 3' strand loss and the formation of fold-back hairpin structures that required resection initiation and Pol32-dependent DNA synthesis. Thus, RPA is required to generate ssDNA, and also to protect ssDNA from degradation and inappropriate annealing that could lead to genome rearrangements.
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Affiliation(s)
- Huan Chen
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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34
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Dziadkowiec D, Kramarz K, Kanik K, Wisniewski P, Carr AM. Involvement of Schizosaccharomyces pombe rrp1+ and rrp2+ in the Srs2- and Swi5/Sfr1-dependent pathway in response to DNA damage and replication inhibition. Nucleic Acids Res 2013; 41:8196-209. [PMID: 23828040 PMCID: PMC3783160 DOI: 10.1093/nar/gkt564] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Previously we identified Rrp1 and Rrp2 as two proteins required for the Sfr1/Swi5-dependent branch of homologous recombination (HR) in Schizosaccharomyces pombe. Here we use a yeast two-hybrid approach to demonstrate that Rrp1 and Rrp2 can interact with each other and with Swi5, an HR mediator protein. Rrp1 and Rrp2 form co-localizing methyl methanesulphonate-induced foci in nuclei, further suggesting they function as a complex. To place the Rrp1/2 proteins more accurately within HR sub-pathways, we carried out extensive epistasis analysis between mutants defining Rrp1/2, Rad51 (recombinase), Swi5 and Rad57 (HR-mediators) plus the anti-recombinogenic helicases Srs2 and Rqh1. We confirm that Rrp1 and Rrp2 act together with Srs2 and Swi5 and independently of Rad57 and show that Rqh1 also acts independently of Rrp1/2. Mutants devoid of Srs2 are characterized by elevated recombination frequency with a concomitant increase in the percentage of conversion-type recombinants. Strains devoid of Rrp1 or Rrp2 did not show a change in HR frequency, but the number of conversion-type recombinants was increased, suggesting a possible function for Rrp1/2 with Srs2 in counteracting Rad51 activity. Our data allow us to propose a model placing Rrp1 and Rrp2 functioning together with Swi5 and Srs2 in a synthesis-dependent strand annealing HR repair pathway.
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Affiliation(s)
- Dorota Dziadkowiec
- Faculty of Biotechnology, Wrocław University, Przybyszewskiego 63-77, 51-148 Wrocław, Poland, Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wrocław, Poland and Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
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35
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Khasanova OS, Vagin DA, Khasanov FK. Recombinational repair in Schizosaccharomyces pombe: The role of mediator proteins. Mol Biol 2012. [DOI: 10.1134/s0026893312050068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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36
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Kuwabara N, Murayama Y, Hashimoto H, Kokabu Y, Ikeguchi M, Sato M, Mayanagi K, Tsutsui Y, Iwasaki H, Shimizu T. Mechanistic insights into the activation of Rad51-mediated strand exchange from the structure of a recombination activator, the Swi5-Sfr1 complex. Structure 2012; 20:440-9. [PMID: 22405003 DOI: 10.1016/j.str.2012.01.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/19/2011] [Accepted: 01/04/2012] [Indexed: 10/28/2022]
Abstract
Rad51 forms a helical filament on single-stranded DNA and promotes strand exchange between two homologous DNA molecules during homologous recombination. The Swi5-Sfr1 complex interacts directly with Rad51 and stimulates strand exchange. Here we describe structural and functional aspects of the complex. Swi5 and the C-terminal core domain of Sfr1 form an essential activator complex with a parallel coiled-coil heterodimer joined firmly together via two previously uncharacterized leucine-zipper motifs and a bundle. The resultant coiled coil is sharply kinked, generating an elongated crescent-shaped structure suitable for transient binding within the helical groove of the Rad51 filament. The N-terminal region of Sfr1, meanwhile, has an interface for binding of Rad51. Our data suggest that the snug fit resulting from the complementary geometry of the heterodimer activates the Rad51 filament and that the N-terminal domain of Sfr1 plays a role in the efficient recruitment of the Swi5-Sfr1 complex to the Rad51 filaments.
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Affiliation(s)
- Naoyuki Kuwabara
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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37
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Tsai SP, Su GC, Lin SW, Chung CI, Xue X, Dunlop MH, Akamatsu Y, Jasin M, Sung P, Chi P. Rad51 presynaptic filament stabilization function of the mouse Swi5-Sfr1 heterodimeric complex. Nucleic Acids Res 2012; 40:6558-69. [PMID: 22492707 PMCID: PMC3413116 DOI: 10.1093/nar/gks305] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Homologous recombination (HR) represents a major error-free pathway to eliminate pre-carcinogenic chromosomal lesions. The DNA strand invasion reaction in HR is mediated by a helical filament of the Rad51 recombinase assembled on single-stranded DNA that is derived from the nucleolytic processing of the primary lesion. Recent studies have found that the human and mouse Swi5 and Sfr1 proteins form a complex that influences Rad51-mediated HR in cells. Here, we provide biophysical evidence that the mouse Swi5–Sfr1 complex has a 1:1 stoichiometry. Importantly, the Swi5–Sfr1 complex, but neither Swi5 nor Sfr1 alone, physically interacts with Rad51 and stimulates Rad51-mediated homologous DNA pairing. This stimulatory effect stems from the stabilization of the Rad51–ssDNA presynaptic filament. Moreover, we provide evidence that the RSfp (rodent Sfr1 proline rich) motif in Sfr1 serves as a negative regulatory element. These results thus reveal an evolutionarily conserved function in the Swi5–Sfr1 complex and furnish valuable information as to the regulatory role of the RSfp motif that isspecific to themammalianSfr1 orthologs.
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Affiliation(s)
- Shang-Pu Tsai
- Institute of Biochemical Sciences, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan
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38
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Okamoto SY, Sato M, Toda T, Yamamoto M. SCF ensures meiotic chromosome segregation through a resolution of meiotic recombination intermediates. PLoS One 2012; 7:e30622. [PMID: 22292001 PMCID: PMC3264600 DOI: 10.1371/journal.pone.0030622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 12/19/2011] [Indexed: 11/21/2022] Open
Abstract
The SCF (Skp1-Cul1-F-box) complex contributes to a variety of cellular events including meiotic cell cycle control, but its function during meiosis is not understood well. Here we describe a novel function of SCF/Skp1 in meiotic recombination and subsequent chromosome segregation. The skp1 temperature-sensitive mutant exhibited abnormal distribution of spindle microtubules in meiosis II, which turned out to originate from abnormal bending of the spindle in meiosis I. Bent spindles were reported in mitosis of this mutant, but it remained unknown how SCF could affect spindle morphology. We found that the meiotic bent spindle in skp1 cells was due to a hypertension generated by chromosome entanglement. The spindle bending was suppressed by inhibiting double strand break (DSB) formation, indicating that the entanglement was generated by the meiotic recombination machinery. Consistently, Rhp51/Rad51-Rad22/Rad52 foci persisted until meiosis I in skp1 cells, proving accumulation of recombination intermediates. Intriguingly bent spindles were also observed in the mutant of Fbh1, an F-box protein containing the DNA helicase domain, which is involved in meiotic recombination. Genetic evidence suggested its cooperation with SCF/Skp1. Thus, SCF/Skp1 together with Fbh1 is likely to function in the resolution of meiotic recombination intermediates, thereby ensuring proper chromosome segregation.
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Affiliation(s)
- Shin-ya Okamoto
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo, Japan
| | - Masamitsu Sato
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo, Japan
- PRESTO, Japan Science and Technology Agency, Honcho Kawaguchi, Saitama, Japan
- * E-mail:
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
| | - Masayuki Yamamoto
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo, Japan
- Kazusa DNA Research Institute, Kisarazu, Chiba, Japan
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39
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Kokabu Y, Murayama Y, Kuwabara N, Oroguchi T, Hashimoto H, Tsutsui Y, Nozaki N, Akashi S, Unzai S, Shimizu T, Iwasaki H, Sato M, Ikeguchi M. Fission yeast Swi5-Sfr1 protein complex, an activator of Rad51 recombinase, forms an extremely elongated dogleg-shaped structure. J Biol Chem 2011; 286:43569-76. [PMID: 22033972 PMCID: PMC3234860 DOI: 10.1074/jbc.m111.303339] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 10/25/2011] [Indexed: 12/03/2022] Open
Abstract
In eukaryotes, DNA strand exchange is the central reaction of homologous recombination, which is promoted by Rad51 recombinases forming a right-handed nucleoprotein filament on single-stranded DNA, also known as a presynaptic filament. Accessory proteins known as recombination mediators are required for the formation of the active presynaptic filament. One such mediator in the fission yeast Schizosaccharomyces pombe is the Swi5-Sfr1 complex, which has been identified as an activator of Rad51 that assists in presynaptic filament formation and stimulates its strand exchange reaction. Here, we determined the 1:1 binding stoichiometry between the two subunits of the Swi5-Sfr1 complex using analytical ultracentrifugation and electrospray ionization mass spectrometry. Small-angle x-ray scattering experiments revealed that the Swi5-Sfr1 complex displays an extremely elongated dogleg-shaped structure in solution, which is consistent with its exceptionally high frictional ratio (f/f(0)) of 2.0 ± 0.2 obtained by analytical ultracentrifugation. Furthermore, we determined a rough topology of the complex by comparing the small-angle x-ray scattering-based structures of the Swi5-Sfr1 complex and four Swi5-Sfr1-Fab complexes, in which the Fab fragments of monoclonal antibodies were specifically bound to experimentally determined sites of Sfr1. We propose a model for how the Swi5-Sfr1 complex binds to the Rad51 filament, in which the Swi5-Sfr1 complex fits into the groove of the Rad51 filament, leading to an active and stable presynaptic filament.
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Affiliation(s)
- Yuichi Kokabu
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | | | - Naoyuki Kuwabara
- the Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomotaka Oroguchi
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | - Hiroshi Hashimoto
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | | | - Naohito Nozaki
- Bio-Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuda-cho, Midori-ku, Yokohama 226-8501, and
| | - Satoko Akashi
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | - Satoru Unzai
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | - Toshiyuki Shimizu
- the Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | | | - Mamoru Sato
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
| | - Mitsunori Ikeguchi
- From the Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045
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40
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Maki K, Inoue T, Onaka A, Hashizume H, Somete N, Kobayashi Y, Murakami S, Shigaki C, Takahashi TS, Masukata H, Nakagawa T. Abundance of prereplicative complexes (Pre-RCs) facilitates recombinational repair under replication stress in fission yeast. J Biol Chem 2011; 286:41701-41710. [PMID: 21971174 DOI: 10.1074/jbc.m111.285619] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mcm2-7 complexes are loaded onto chromatin with the aid of Cdt1 and Cdc18/Cdc6 and form prereplicative complexes (pre-RCs) at multiple sites on each chromosome. Pre-RCs are essential for DNA replication and surviving replication stress. However, the mechanism by which pre-RCs contribute to surviving replication stress is largely unknown. Here, we isolated the fission yeast mcm6-S1 mutant that was hypersensitive to methyl methanesulfonate (MMS) and camptothecin (CPT), both of which cause forks to collapse. The mcm6-S1 mutation impaired the interaction with Cdt1 and decreased the binding of minichromosome maintenance (MCM) proteins to replication origins. Overexpression of Cdt1 restored MCM binding and suppressed the sensitivity to MMS and CPT, suggesting that the Cdt1-Mcm6 interaction is important for the assembly of pre-RCs and the repair of collapsed forks. MMS-induced Chk1 phosphorylation and Rad22/Rad52 focus formation occurred normally, whereas cells containing Rhp54/Rad54 foci, which are involved in DNA strand exchange and dissociation of the joint molecules, were increased. Remarkably, G(1) phase extension through deletion of an S phase cyclin, Cig2, as well as Cdt1 overexpression restored pre-RC assembly and suppressed Rhp54 accumulation. A cdc18 mutation also caused hypersensitivity to MMS and CPT and accumulation of Rhp54 foci. These data suggest that an abundance of pre-RCs facilitates a late step in the recombinational repair of collapsed forks in the following S phase.
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Affiliation(s)
- Kentaro Maki
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takahiro Inoue
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Atsushi Onaka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hiroko Hashizume
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Naoko Somete
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuko Kobayashi
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Shigefumi Murakami
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Chikako Shigaki
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Tatsuro S Takahashi
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hisao Masukata
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
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41
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The epistatic relationship between BRCA2 and the other RAD51 mediators in homologous recombination. PLoS Genet 2011; 7:e1002148. [PMID: 21779174 PMCID: PMC3136442 DOI: 10.1371/journal.pgen.1002148] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 05/02/2011] [Indexed: 02/06/2023] Open
Abstract
RAD51 recombinase polymerizes at the site of double-strand breaks (DSBs) where it performs DSB repair. The loss of RAD51 causes extensive chromosomal breaks, leading to apoptosis. The polymerization of RAD51 is regulated by a number of RAD51 mediators, such as BRCA1, BRCA2, RAD52, SFR1, SWS1, and the five RAD51 paralogs, including XRCC3. We here show that brca2-null mutant cells were able to proliferate, indicating that RAD51 can perform DSB repair in the absence of BRCA2. We disrupted the BRCA1, RAD52, SFR1, SWS1, and XRCC3 genes in the brca2-null cells. All the resulting double-mutant cells displayed a phenotype that was very similar to that of the brca2-null cells. We suggest that BRCA2 might thus serve as a platform to recruit various RAD51 mediators at the appropriate position at the DNA–damage site. Mutations in BRCA1 and BRCA2 predispose hereditary breast and ovarian cancer. Such mutations sensitize to chemotherapeutic agents, including camptothecin, cisplatin, and poly(ADP-ribose) polymerase (PARP) inhibitor, since RAD51 mediators including both BRCA proteins promote repair of DNA lesions induced by these drugs. Little is known of the functional relationships among RAD51, BRCA2, and other RAD51 mediators, because no brca2-null cells were available. Furthermore, the phenotype of sws1 mutants has not been documented. We here disrupted every known RAD51 mediator and analyzed the phenotype of the resulting mutants in both BRCA2-deficient and -proficient backgrounds. The understanding of the function of individual RAD51 mediators and their functional interactions will contribute to the accurate prediction of anti-cancer therapy efficacy.
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42
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Murayama Y, Tsutsui Y, Iwasaki H. The fission yeast meiosis-specific Dmc1 recombinase mediates formation and branch migration of Holliday junctions by preferentially promoting strand exchange in a direction opposite to that of Rad51. Genes Dev 2011; 25:516-27. [PMID: 21363965 DOI: 10.1101/gad.1997511] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Homologous recombination proceeds via the formation of several intermediates including Holliday junctions (HJs), which are important for creating crossover products. DNA strand exchange is a core reaction that produces these intermediates that is directly catalyzed by RecA family recombinases, of which there are two types in eukaryotes: universal Rad51 and meiosis-specific Dmc1. We demonstrated previously that Rad51 promotes four-strand exchange, mimicking the formation and branch migration of HJs. Here we show that Dmc1 from fission yeast has a similar activity, which requires ATP hydrolysis and is independent of an absolute requirement for the Swi5-Sfr1 complex. These features are critically different from three-strand exchange mediated by Dmc1, but similar to those of four-strand exchange mediated by Rad51, suggesting that strand exchange reactions between duplex-duplex and single-duplex DNAs are mechanistically different. Interestingly, despite similarities in protein structure and in reaction features, the preferential polarities of Dmc1 and Rad51 strand exchange are different (Dmc1 promotes exchange in the 5'-to-3' direction and Rad51 promotes exchange in the 3'-to-5' direction relative to the ssDNA region of the DNA substrate). The significance of the Dmc1 polarity is discussed within the context of the necessity for crossover production.
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Affiliation(s)
- Yasuto Murayama
- Department of Life Science, School and Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Kanagawa 226-8501, Japan
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43
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Murayama Y, Iwasaki H. An in vitro assay for monitoring the formation and branch migration of holliday junctions mediated by a eukaryotic recombinase. Methods Mol Biol 2011; 745:385-405. [PMID: 21660706 DOI: 10.1007/978-1-61779-129-1_22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA strand exchange is a core reaction of homologous recombination directly catalyzed by Rad51/Dmc1 RecA family recombinases in eukaryotes. This reaction proceeds through the formation of several DNA intermediates. The X-shaped four-way DNA structure known as a Holliday junction (HJ) is a central intermediate in homologous recombination. Genetic and biochemical studies indicate that the HJ is important for the production of crossover-type recombinants, which are reciprocal exchange products. According to a recombination model for the repair of DNA double-strand breaks, the formation of HJs requires a reciprocal duplex-duplex DNA exchange known as the DNA four-strand exchange reaction. In vitro analyses using purified recombination proteins and model DNA substrates provide a mechanistic insight into the DNA strand exchange reaction, including the steps leading to the formation and branch migration of Holliday junctions.
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Affiliation(s)
- Yasuto Murayama
- Cancer Research UK, London Research Institute, 44, Lincoln's Inn Fields, London, WC2A 3LY, UK.
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44
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Akamatsu Y, Jasin M. Role for the mammalian Swi5-Sfr1 complex in DNA strand break repair through homologous recombination. PLoS Genet 2010; 6:e1001160. [PMID: 20976249 PMCID: PMC2954829 DOI: 10.1371/journal.pgen.1001160] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 09/15/2010] [Indexed: 01/08/2023] Open
Abstract
In fission yeast, the Swi5-Sfr1 complex plays an important role in homologous recombination (HR), a pathway crucial for the maintenance of genomic integrity. Here we identify and characterize mammalian Swi5 and Sfr1 homologues. Mouse Swi5 and Sfr1 are nuclear proteins that form a complex in vivo and in vitro. Swi5 interacts in vitro with Rad51, the DNA strand-exchange protein which functions during HR. By generating Swi5−/− and Sfr1−/− embryonic stem cell lines, we found that both proteins are mutually interdependent for their stability. Importantly, the Swi5-Sfr1 complex plays a role in HR when Rad51 function is perturbed in vivo by expression of a BRC peptide from BRCA2. Swi5−/− and Sfr1−/− cells are selectively sensitive to agents that cause DNA strand breaks, in particular ionizing radiation, camptothecin, and the Parp inhibitor olaparib. Consistent with a role in HR, sister chromatid exchange induced by Parp inhibition is attenuated in Swi5−/− and Sfr1−/− cells, and chromosome aberrations are increased. Thus, Swi5-Sfr1 is a newly identified complex required for genomic integrity in mammalian cells with a specific role in the repair of DNA strand breaks. Our genome constantly undergoes DNA damage as a result of agents in the environment, as well as from metabolic processes. One method of repairing DNA damage is homologous recombination (HR), in which genetic information from a duplicate sequence (the sister chromatid) is copied into the damaged site in DNA. In model organisms (the yeasts), a protein complex termed Swi5-Sfr1 functions in DNA damage repair by HR. In this study, we characterize mouse homologues of this complex. We find that mouse cells lacking this complex are sensitive to DNA damaging agents, in particular, those that cause breaks in DNA strands and that serve as cancer chemotherapeutics. These cells also have increased numbers of chromosome aberrations when exposed to DNA damaging agents. Moreover, HR is decreased in Swi5 and Sfr1 mutant cells under conditions where the cell is challenged. Together, these results demonstrate a requirement for the Swi5-Sfr1 protein complex in maintaining genomic integrity in mammalian cells.
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Affiliation(s)
- Yufuko Akamatsu
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- * E-mail:
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45
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Cavero S, Limbo O, Russell P. Critical functions of Rpa3/Ssb3 in S-phase DNA damage responses in fission yeast. PLoS Genet 2010; 6:e1001138. [PMID: 20885790 PMCID: PMC2944793 DOI: 10.1371/journal.pgen.1001138] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 08/24/2010] [Indexed: 11/24/2022] Open
Abstract
Replication Protein A (RPA) is a heterotrimeric, single-stranded DNA (ssDNA)–binding complex required for DNA replication and repair, homologous recombination, DNA damage checkpoint signaling, and telomere maintenance. Whilst the larger RPA subunits, Rpa1 and Rpa2, have essential interactions with ssDNA, the molecular functions of the smallest subunit Rpa3 are unknown. Here, we investigate the Rpa3 ortholog Ssb3 in Schizosaccharomyces pombe and find that it is dispensable for cell viability, checkpoint signaling, RPA foci formation, and meiosis. However, increased spontaneous Rad11Rpa1 and Rad22Rad52 nuclear foci in ssb3Δ cells indicate genome maintenance defects. Moreover, Ssb3 is required for resistance to genotoxins that disrupt DNA replication. Genetic interaction studies indicate that Ssb3 has a close functional relationship with the Mms1-Mms22 protein complex, which is required for survival after DNA damage in S-phase, and with the mitotic functions of Mus81-Eme1 Holliday junction resolvase that is required for recovery from replication fork collapse. From these studies we propose that Ssb3 plays a critical role in mediating RPA functions that are required for repair or tolerance of DNA lesions in S-phase. Rpa3 orthologs in humans and other species may have a similar function. Proteins that bind single-stranded DNA (ssDNA) are essential for DNA replication, most types of DNA repair including homologous recombination, DNA damage signaling, and maintenance of telomeres. In eukaryotes, the most ubiquitous and abundant ssDNA binding protein is Replication Protein A (RPA), a 3-subunit protein complex consisting of large (Rpa1), medium (Rpa2), and small (Rpa3) subunits. Rpa1 and Rpa2 directly bind ssDNA, whilst the function of Rpa3 is largely unknown. Here, we discover that in fission yeast a 2-subunit complex of Rpa1 and Rpa2 is sufficient for the essential DNA replication function of RPA and its role in homologous recombination repair of double-strand breaks. Rpa3 is not required for these functions, but it is needed for survival of many types of DNA damage that stall or collapse replication forks. Genetic studies indicate close functional links between the Rpa3-dependent activities of RPA, the repair of collapsed replication forks by Mus81-Eme1 Holliday junction resolvase, and the newly discovered Mms1-Mms22 protein complex that is essential for resistance to genotoxins that disrupt DNA replication.
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Affiliation(s)
- Santiago Cavero
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Oliver Limbo
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Paul Russell
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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46
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Kuwabara N, Hashimoto H, Yamada N, Unzai S, Ikeguchi M, Sato M, Murayama Y, Iwasaki H, Shimizu T. Expression, purification and crystallization of Swi5 and the Swi5-Sfr1 complex from fission yeast. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:1124-6. [PMID: 20823543 DOI: 10.1107/s1744309110032239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 08/11/2010] [Indexed: 01/21/2023]
Abstract
The assembly of the presynaptic filament of recombinases represents the most important step in homologous recombination. The formation of the filament requires assistance from mediator proteins. Swi5 and Sfr1 have been identified as mediators in fission yeast and these proteins form a complex that stimulates strand exchange. Here, the expression, purification and crystallization of Swi5 and its complex with an N-terminally truncated form of Sfr1 (DeltaN180Sfr1) are presented. Analytical ultracentrifugation of the purified samples showed that Swi5 and the protein complex exist as tetramers and heterodimers in solution, respectively. Swi5 was crystallized in two forms belonging to space groups C2 and R3 and the crystals diffracted to 2.7 A resolution. Swi5-DeltaN180Sfr1 was crystallized in space group P2(1)2(1)2 and the crystals diffracted to 2.3 A resolution. The crystals of Swi5 and Swi5-DeltaN180Sfr1 are likely to contain one tetramer and two heterodimers in the asymmetric unit, respectively.
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Affiliation(s)
- Naoyuki Kuwabara
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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47
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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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48
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Takizawa Y, Qing Y, Takaku M, Ishida T, Morozumi Y, Tsujita T, Kogame T, Hirota K, Takahashi M, Shibata T, Kurumizaka H, Takeda S. GEMIN2 promotes accumulation of RAD51 at double-strand breaks in homologous recombination. Nucleic Acids Res 2010; 38:5059-74. [PMID: 20403813 PMCID: PMC2926616 DOI: 10.1093/nar/gkq271] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
RAD51 is a key factor in homologous recombination (HR) and plays an essential role in cellular proliferation by repairing DNA damage during replication. The assembly of RAD51 at DNA damage is strictly controlled by RAD51 mediators, including BRCA1 and BRCA2. We found that human RAD51 directly binds GEMIN2/SIP1, a protein involved in spliceosome biogenesis. Biochemical analyses indicated that GEMIN2 enhances the RAD51–DNA complex formation by inhibiting RAD51 dissociation from DNA, and thereby stimulates RAD51-mediated homologous pairing. GEMIN2 also enhanced the RAD51-mediated strand exchange, when RPA was pre-bound to ssDNA before the addition of RAD51. To analyze the function of GEMIN2, we depleted GEMIN2 in the chicken DT40 line and in human cells. The loss of GEMIN2 reduced HR efficiency and resulted in a significant decrease in the number of RAD51 subnuclear foci, as observed in cells deficient in BRCA1 and BRCA2. These observations and our biochemical analyses reveal that GEMIN2 regulates HR as a novel RAD51 mediator.
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Affiliation(s)
- Yoshimasa Takizawa
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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49
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Cipak L, Spirek M, Novatchkova M, Chen Z, Rumpf C, Lugmayr W, Mechtler K, Ammerer G, Csaszar E, Gregan J. An improved strategy for tandem affinity purification-tagging of Schizosaccharomyces pombe genes. Proteomics 2010; 9:4825-8. [PMID: 19750511 DOI: 10.1002/pmic.200800948] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Tandem affinity purification (TAP) is a method that allows rapid purification of native protein complexes. We developed an improved technique to fuse the fission yeast genes with a TAP tag. Our technique is based on tagging constructs that contain regions homologous to the target gene cloned into vectors carrying a TAP tag. We used this technique to design strategies for TAP-tagging of predicted Schizosaccharomyces pombe genes (http://mendel.imp.ac.at/Pombe_tagging/). To validate the approach, we purified the proteins, which associated with two evolutionarily conserved proteins Swi5 and Sfr1 as well as three protein kinases Ksg1, Orb6 and Sid1.
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Affiliation(s)
- Lubos Cipak
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
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50
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Current awareness on yeast. Yeast 2008. [DOI: 10.1002/yea.1558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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