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Palacios-Blanco I, Gómez L, Bort M, Mayerová N, Bágeľová Poláková S, Martín-Castellanos C. CDK phosphorylation of Sfr1 downregulates Rad51 function in late-meiotic homolog invasions. EMBO J 2024:10.1038/s44318-024-00205-2. [PMID: 39174851 DOI: 10.1038/s44318-024-00205-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 08/05/2024] [Accepted: 08/08/2024] [Indexed: 08/24/2024] Open
Abstract
Meiosis is the developmental program that generates gametes. To produce healthy gametes, meiotic recombination creates reciprocal exchanges between each pair of homologous chromosomes that facilitate faithful chromosome segregation. Using fission yeast and biochemical, genetic, and cytological approaches, we have studied the role of CDK (cyclin-dependent kinase) in the control of Swi5-Sfr1, a Rad51-recombinase auxiliary factor involved in homolog invasion during recombination. We show that Sfr1 is a CDK target, and its phosphorylation downregulates Swi5-Sfr1 function in the meiotic prophase. Expression of a phospho-mimetic sfr1-7D mutant inhibits Rad51 binding, its robust chromosome loading, and subsequently decreases interhomolog recombination. On the other hand, the non-phosphorylatable sfr1-7A mutant alters Rad51 dynamics at late prophase, and exacerbates chromatin segregation defects and Rad51 retention observed in dbl2 deletion mutants when combined with them. We propose Sfr1 phospho-inhibition as a novel cell-cycle-dependent mechanism, which ensures timely resolution of recombination intermediates and successful chromosome distribution into the gametes. Furthermore, the N-terminal disordered part of Sfr1, an evolutionarily conserved feature, serves as a regulatory platform coordinating this phospho-regulation, protein localization and stability, with several CDK sites and regulatory sequences being conserved.
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Affiliation(s)
- Inés Palacios-Blanco
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-USAL, Salamanca, 37007, Spain
| | - Lucía Gómez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-USAL, Salamanca, 37007, Spain
| | - María Bort
- Instituto de Biología Funcional y Genómica (IBFG), CSIC-USAL, Salamanca, 37007, Spain
| | - Nina Mayerová
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, 841 04, Slovakia
| | - Silvia Bágeľová Poláková
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, 841 04, Slovakia
- Centre of Biosciences SAS, Institute of Animal Biochemistry and Genetics, Bratislava, 840 05, Slovakia
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2
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Lorenz A, Mpaulo SJ. Gene conversion: a non-Mendelian process integral to meiotic recombination. Heredity (Edinb) 2022; 129:56-63. [PMID: 35393552 PMCID: PMC9273591 DOI: 10.1038/s41437-022-00523-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 12/30/2022] Open
Abstract
Meiosis is undoubtedly the mechanism that underpins Mendelian genetics. Meiosis is a specialised, reductional cell division which generates haploid gametes (reproductive cells) carrying a single chromosome complement from diploid progenitor cells harbouring two chromosome sets. Through this process, the hereditary material is shuffled and distributed into haploid gametes such that upon fertilisation, when two haploid gametes fuse, diploidy is restored in the zygote. During meiosis the transient physical connection of two homologous chromosomes (one originally inherited from each parent) each consisting of two sister chromatids and their subsequent segregation into four meiotic products (gametes), is what enables genetic marker assortment forming the core of Mendelian laws. The initiating events of meiotic recombination are DNA double-strand breaks (DSBs) which need to be repaired in a certain way to enable the homologous chromosomes to find each other. This is achieved by DSB ends searching for homologous repair templates and invading them. Ultimately, the repair of meiotic DSBs by homologous recombination physically connects homologous chromosomes through crossovers. These physical connections provided by crossovers enable faithful chromosome segregation. That being said, the DSB repair mechanism integral to meiotic recombination also produces genetic transmission distortions which manifest as postmeiotic segregation events and gene conversions. These processes are non-reciprocal genetic exchanges and thus non-Mendelian.
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Affiliation(s)
- Alexander Lorenz
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK.
| | - Samantha J Mpaulo
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK
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3
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Rad54 and Rdh54 prevent Srs2-mediated disruption of Rad51 presynaptic filaments. Proc Natl Acad Sci U S A 2022; 119:2113871119. [PMID: 35042797 PMCID: PMC8795549 DOI: 10.1073/pnas.2113871119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2021] [Indexed: 11/18/2022] Open
Abstract
Homologous DNA recombination is an essential pathway necessary for the repair of double-stranded DNA breaks. Defects in this pathway are associated with hereditary breast cancer, ovarian cancer, and cancer-prone syndromes. Although essential, too much recombination is also bad and can lead to genetic mutations. Thus, cells have evolved “antirecombinase” enzymes that can actively dismantle recombination intermediates to prevent excessive recombination. However, our current understanding of how antirecombinases are themselves regulated remains very limited. Here, we study the antirecombinase Srs2 and its regulation by the recombination accessory factors Rad54 and Rdh54. Our data suggest that Rad54 and Rdh54 act synergistically to function as key regulators of Srs2, thus serving as “licensing factors” that enable timely progression of DNA repair. Srs2 is a superfamily 1 (SF1) helicase that participates in several pathways necessary for the repair of damaged DNA. Srs2 regulates formation of early homologous recombination (HR) intermediates by actively removing the recombinase Rad51 from single-stranded DNA (ssDNA). It is not known whether and how Srs2 itself is down-regulated to allow for timely HR progression. Rad54 and Rdh54 are two closely related superfamily 2 (SF2) motor proteins that promote the formation of Rad51-dependent recombination intermediates. Rad54 and Rdh54 bind tightly to Rad51-ssDNA and act downstream of Srs2, suggesting that they may affect the ability of Srs2 to dismantle Rad51 filaments. Here, we used DNA curtains to determine whether Rad54 and Rdh54 alter the ability of Srs2 to disrupt Rad51 filaments. We show that Rad54 and Rdh54 act synergistically to greatly restrict the antirecombinase activity of Srs2. Our findings suggest that Srs2 may be accorded only a limited time window to act and that Rad54 and Rdh54 fulfill a role of prorecombinogenic licensing factors.
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4
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Meir A, Greene EC. Srs2 and Pif1 as Model Systems for Understanding Sf1a and Sf1b Helicase Structure and Function. Genes (Basel) 2021; 12:1319. [PMID: 34573298 PMCID: PMC8469786 DOI: 10.3390/genes12091319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/19/2023] Open
Abstract
Helicases are enzymes that convert the chemical energy stored in ATP into mechanical work, allowing them to move along and manipulate nucleic acids. The helicase superfamily 1 (Sf1) is one of the largest subgroups of helicases and they are required for a range of cellular activities across all domains of life. Sf1 helicases can be further subdivided into two classes called the Sf1a and Sf1b helicases, which move in opposite directions on nucleic acids. The results of this movement can range from the separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. Here, we describe the characteristics of the Sf1a helicase Srs2 and the Sf1b helicase Pif1, both from the model organism Saccharomyces cerevisiae, focusing on the roles that they play in homologous recombination, a DNA repair pathway that is necessary for maintaining genome integrity.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA;
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5
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Brown SD, Mpaulo SJ, Asogwa MN, Jézéquel M, Whitby MC, Lorenz A. DNA sequence differences are determinants of meiotic recombination outcome. Sci Rep 2019; 9:16446. [PMID: 31712578 PMCID: PMC6848502 DOI: 10.1038/s41598-019-52907-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/25/2019] [Indexed: 11/08/2022] Open
Abstract
Meiotic recombination is essential for producing healthy gametes, and also generates genetic diversity. DNA double-strand break (DSB) formation is the initiating step of meiotic recombination, producing, among other outcomes, crossovers between homologous chromosomes (homologs), which provide physical links to guide accurate chromosome segregation. The parameters influencing DSB position and repair are thus crucial determinants of reproductive success and genetic diversity. Using Schizosaccharomyces pombe, we show that the distance between sequence polymorphisms across homologs has a strong impact on meiotic recombination rate. The closer the sequence polymorphisms are to each other across the homologs the fewer recombination events were observed. In the immediate vicinity of DSBs, sequence polymorphisms affect the frequency of intragenic recombination events (gene conversions). Additionally, and unexpectedly, the crossover rate of flanking markers tens of kilobases away from the sequence polymorphisms was affected by their relative position to each other amongst the progeny having undergone intragenic recombination. A major regulator of this distance-dependent effect is the MutSα-MutLα complex consisting of Msh2, Msh6, Mlh1, and Pms1. Additionally, the DNA helicases Rqh1 and Fml1 shape recombination frequency, although the effects seen here are largely independent of the relative position of the sequence polymorphisms.
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Affiliation(s)
- Simon D Brown
- The Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
- MRC Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Samantha J Mpaulo
- The Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Mimi N Asogwa
- The Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Marie Jézéquel
- The Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Matthew C Whitby
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Alexander Lorenz
- The Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
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6
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Steinfeld JB, Beláň O, Kwon Y, Terakawa T, Al-Zain A, Smith MJ, Crickard JB, Qi Z, Zhao W, Rothstein R, Symington LS, Sung P, Boulton SJ, Greene EC. Defining the influence of Rad51 and Dmc1 lineage-specific amino acids on genetic recombination. Genes Dev 2019; 33:1191-1207. [PMID: 31371435 PMCID: PMC6719624 DOI: 10.1101/gad.328062.119] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/01/2019] [Indexed: 02/06/2023]
Abstract
The vast majority of eukaryotes possess two DNA recombinases: Rad51, which is ubiquitously expressed, and Dmc1, which is meiosis-specific. The evolutionary origins of this two-recombinase system remain poorly understood. Interestingly, Dmc1 can stabilize mismatch-containing base triplets, whereas Rad51 cannot. Here, we demonstrate that this difference can be attributed to three amino acids conserved only within the Dmc1 lineage of the Rad51/RecA family. Chimeric Rad51 mutants harboring Dmc1-specific amino acids gain the ability to stabilize heteroduplex DNA joints with mismatch-containing base triplets, whereas Dmc1 mutants with Rad51-specific amino acids lose this ability. Remarkably, RAD-51 from Caenorhabditis elegans, an organism without Dmc1, has acquired "Dmc1-like" amino acids. Chimeric C. elegans RAD-51 harboring "canonical" Rad51 amino acids gives rise to toxic recombination intermediates, which must be actively dismantled to permit normal meiotic progression. We propose that Dmc1 lineage-specific amino acids involved in the stabilization of heteroduplex DNA joints with mismatch-containing base triplets may contribute to normal meiotic recombination.
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Affiliation(s)
- Justin B Steinfeld
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Ondrej Beláň
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
| | - Tsuyoshi Terakawa
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Amr Al-Zain
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Michael J Smith
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - J Brooks Crickard
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Zhi Qi
- Center for Quantitative Biology, Peking University-Tsinghua University Joint Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Weixing Zhao
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
| | - Rodney Rothstein
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Lorraine S Symington
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
| | - Simon J Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, New York 10032, USA
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7
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Crickard J, Xue C, Wang W, Kwon Y, Sung P, Greene E. The RecQ helicase Sgs1 drives ATP-dependent disruption of Rad51 filaments. Nucleic Acids Res 2019; 47:4694-4706. [PMID: 30916344 PMCID: PMC6511845 DOI: 10.1093/nar/gkz186] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/06/2019] [Accepted: 03/20/2019] [Indexed: 12/21/2022] Open
Abstract
DNA helicases of the RecQ family are conserved among the three domains of life and play essential roles in genome maintenance. Mutations in several human RecQ helicases lead to diseases that are marked by cancer predisposition. The Saccharomyces cerevisiae RecQ helicase Sgs1 is orthologous to human BLM, defects in which cause the cancer-prone Bloom's Syndrome. Here, we use single-molecule imaging to provide a quantitative mechanistic understanding of Sgs1 activities on single stranded DNA (ssDNA), which is a central intermediate in all aspects of DNA metabolism. We show that Sgs1 acts upon ssDNA bound by either replication protein A (RPA) or the recombinase Rad51. Surprisingly, we find that Sgs1 utilizes a novel motor mechanism for disrupting ssDNA intermediates bound by the recombinase protein Rad51. The ability of Sgs1 to disrupt Rad51-ssDNA filaments may explain some of the defects engendered by RECQ helicase deficiencies in human cells.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Chaoyou Xue
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, TX 78229, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY 10032, USA
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8
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Hunt LJ, Ahmed EA, Kaur H, Ahuja JS, Hulme L, Chou TC, Lichten M, Goldman ASH. S. cerevisiae Srs2 helicase ensures normal recombination intermediate metabolism during meiosis and prevents accumulation of Rad51 aggregates. Chromosoma 2019; 128:249-265. [PMID: 31069484 PMCID: PMC6823294 DOI: 10.1007/s00412-019-00705-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 04/04/2019] [Accepted: 04/24/2019] [Indexed: 01/06/2023]
Abstract
We investigated the meiotic role of Srs2, a multi-functional DNA helicase/translocase that destabilises Rad51-DNA filaments and is thought to regulate strand invasion and prevent hyper-recombination during the mitotic cell cycle. We find that Srs2 activity is required for normal meiotic progression and spore viability. A significant fraction of srs2 mutant cells progress through both meiotic divisions without separating the bulk of their chromatin, although in such cells sister centromeres often separate. Undivided nuclei contain aggregates of Rad51 colocalised with the ssDNA-binding protein RPA, suggesting the presence of persistent single-strand DNA. Rad51 aggregate formation requires Spo11-induced DSBs, Rad51 strand-invasion activity and progression past the pachytene stage of meiosis, but not the DSB end-resection or the bias towards interhomologue strand invasion characteristic of normal meiosis. srs2 mutants also display altered meiotic recombination intermediate metabolism, revealed by defects in the formation of stable joint molecules. We suggest that Srs2, by limiting Rad51 accumulation on DNA, prevents the formation of aberrant recombination intermediates that otherwise would persist and interfere with normal chromosome segregation and nuclear division.
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Affiliation(s)
- Laura J Hunt
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RQ, UK
| | - Emad A Ahmed
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK.,Immunology and Molecular Physiology Lab., Zoology Department, Faculty of Science, Assiut University, Markaz El-Fath, 71515, Egypt
| | - Hardeep Kaur
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.,Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, 78229, USA
| | - Jasvinder S Ahuja
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA
| | - Lydia Hulme
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK
| | - Ta-Chung Chou
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK.,All First Tech Co., Ltd, 32467, No 146-2. Hung Chun Road, Ping Zhen Dist, Taoyuan City, Taiwan
| | - Michael Lichten
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA
| | - Alastair S H Goldman
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, S10 2TN, UK. .,Faculty of Life Sciences, The University of Bradford, Bradford, BD7 1AZ, UK.
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9
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Crickard JB, Greene EC. Helicase Mechanisms During Homologous Recombination in Saccharomyces cerevisiae. Annu Rev Biophys 2019; 48:255-273. [PMID: 30857400 DOI: 10.1146/annurev-biophys-052118-115418] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Helicases are enzymes that move, manage, and manipulate nucleic acids. They can be subdivided into six super families and are required for all aspects of nucleic acid metabolism. In general, all helicases function by converting the chemical energy stored in the bond between the gamma and beta phosphates of adenosine triphosphate into mechanical work, which results in the unidirectional movement of the helicase protein along one strand of a nucleic acid. The results of this translocation activity can range from separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. In this review, we focus on describing key helicases from the model organism Saccharomyces cerevisiae that contribute to the regulation of homologous recombination, which is an essential DNA repair pathway for fixing damaged chromosomes.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; ,
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; ,
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10
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CDK contribution to DSB formation and recombination in fission yeast meiosis. PLoS Genet 2019; 15:e1007876. [PMID: 30640914 PMCID: PMC6331086 DOI: 10.1371/journal.pgen.1007876] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 12/04/2018] [Indexed: 12/19/2022] Open
Abstract
CDKs (cyclin-dependent kinases) associate with different cyclins to form different CDK-complexes that are fundamental for an ordered cell cycle progression, and the coordination of this progression with different aspects of the cellular physiology. During meiosis programmed DNA double-strand breaks (DSBs) initiate recombination that in addition to generating genetic variability are essential for the reductional chromosome segregation during the first meiotic division, and therefore for genome stability and viability of the gametes. However, how meiotic progression and DSB formation are coordinated, and the role CDKs have in the process, is not well understood. We have used single and double cyclin deletion mutants, and chemical inhibition of global CDK activity using the cdc2-asM17 allele, to address the requirement of CDK activity for DSB formation and recombination in fission yeast. We report that several cyclins (Cig1, Cig2, and the meiosis-specific Crs1) control DSB formation and recombination, with a major contribution of Crs1. Moreover, complementation analysis indicates specificity at least for this cyclin, suggesting that different CDK complexes might act in different pathways to promote recombination. Down-regulation of CDK activity impinges on the formation of linear elements (LinEs, protein complexes required for break formation at most DSB hotspot sites). This defect correlates with a reduction in the capability of one structural component (Rec25) to bind chromatin, suggesting a molecular mechanism by which CDK controls break formation. However, reduction in DSB formation in cyclin deletion mutants does not always correspondingly correlate with a proportional reduction in meiotic recombination (crossovers), suggesting that specific CDK complexes might also control downstream events balancing repair pathways. Therefore, our work points to CDK regulation of DSB formation as a key conserved feature in the initiation of meiotic recombination, in addition to provide a view of possible roles CDK might have in other steps of the recombination process. Meiotic division is a cell division process where a single round of DNA replication is followed by two sequential chromosome segregations, the first reductional (homologous chromosomes separate) and the second equational (sister chromatids segregate). As a consequence diploid organisms halve ploidy, producing haploid gametes that after fertilization generate a new diploid organism with a complete chromosome complement. At early stages of meiosis physical exchange between homologous chromosomes ensures the accurate following reductional segregation. Physical exchange is provided by recombination that initiates with highly-controlled self-inflicted DNA damage (DSBs, double strand breaks). We have found that the conserved CDK (cyclin-dependent kinase) activity controls DSB formation in fission yeast. Available data were uncertain about the conservation of CDK in the process, and thus our work points to a broad evolutionary conservation of this regulation. Regulation is exerted at least by controlling chromatin-binding of one structural component of linear elements, a protein complex related to the synaptonemal complex and required for high levels of DSBs. Correspondingly, depletion of CDK activity impairs formation of these structures. In addition, CDK might control homeostatic mechanisms, critical to maintain efficient levels of recombination across the genome and, therefore, high rates of genetic exchange between parental chromosomes.
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11
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Meiosis-specific recombinase Dmc1 is a potent inhibitor of the Srs2 antirecombinase. Proc Natl Acad Sci U S A 2018; 115:E10041-E10048. [PMID: 30301803 DOI: 10.1073/pnas.1810457115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cross-over recombination products are a hallmark of meiosis because they are necessary for accurate chromosome segregation and they also allow for increased genetic diversity during sexual reproduction. However, cross-overs can also cause gross chromosomal rearrangements and are therefore normally down-regulated during mitotic growth. The mechanisms that enhance cross-over product formation upon entry into meiosis remain poorly understood. In Saccharomyces cerevisiae, the Superfamily 1 (Sf1) helicase Srs2, which is an ATP hydrolysis-dependent motor protein that actively dismantles recombination intermediates, promotes synthesis-dependent strand annealing, the result of which is a reduction in cross-over recombination products. Here, we show that the meiosis-specific recombinase Dmc1 is a potent inhibitor of Srs2. Biochemical and single-molecule assays demonstrate that Dmc1 acts by inhibiting Srs2 ATP hydrolysis activity, which prevents the motor protein from undergoing ATP hydrolysis-dependent translocation on Dmc1-bound recombination intermediates. We propose a model in which Dmc1 helps contribute to cross-over formation during meiosis by antagonizing the antirecombinase activity of Srs2.
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12
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Abstract
Homologous recombination (HR) is a universally conserved mechanism used to maintain genomic integrity. In eukaryotes, HR is used to repair the spontaneous double strand breaks (DSBs) that arise during mitotic growth, and the programmed DSBs that form during meiosis. The mechanisms that govern mitotic and meiotic HR share many similarities, however, there are also several key differences, which reflect the unique attributes of each process. For instance, even though many of the proteins involved in mitotic and meiotic HR are the same, DNA target specificity is not: mitotic DSBs are repaired primarily using the sister chromatid as a template, whereas meiotic DBSs are repaired primarily through targeting of the homologous chromosome. These changes in template specificity are induced by expression of meiosis-specific HR proteins, down-regulation of mitotic HR proteins, and the formation of meiosis-specific chromosomal structures. Here, we compare and contrast the biochemical properties of key recombination intermediates formed during the pre-synapsis phase of mitotic and meiotic HR. Throughout, we try to highlight unanswered questions that will shape our understanding of how homologous recombination contributes to human cancer biology and sexual reproduction.
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13
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Genetic interactions between the chromosome axis-associated protein Hop1 and homologous recombination determinants in Schizosaccharomyces pombe. Curr Genet 2018; 64:1089-1104. [PMID: 29550859 PMCID: PMC6153652 DOI: 10.1007/s00294-018-0827-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 03/14/2018] [Indexed: 11/28/2022]
Abstract
Hop1 is a component of the meiosis-specific chromosome axis and belongs to the evolutionarily conserved family of HORMA domain proteins. Hop1 and its orthologs in higher eukaryotes are a major factor in promoting double-strand DNA break formation and inter-homolog recombination. In budding yeast and mammals, they are also involved in a meiotic checkpoint kinase cascade monitoring the completion of double-strand DNA break repair. We used the fission yeast, Schizosaccharomyces pombe, which lacks a canonical synaptonemal complex to test whether Hop1 has a role beyond supporting the generation of double-strand DNA breaks and facilitating inter-homolog recombination events. We determined how mutants of homologous recombination factors genetically interact with hop1, studied the role(s) of the HORMA domain of Hop1, and characterized a bio-informatically predicted interactor of Hop1, Aho1 (SPAC688.03c). Our observations indicate that in fission yeast, Hop1 does require its HORMA domain to support wild-type levels of meiotic recombination and localization to meiotic chromatin. Furthermore, we show that hop1∆ only weakly interacts genetically with mutants of homologous recombination factors, and in fission yeast likely has no major role beyond break formation and promoting inter-homolog events. We speculate that after the evolutionary loss of the synaptonemal complex, Hop1 likely has become less important for modulating recombination outcome during meiosis in fission yeast, and that this led to a concurrent rewiring of genetic pathways controlling meiotic recombination.
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Zhang X, St. Leger RJ, Fang W. Stress-induced pyruvate accumulation contributes to cross protection in a fungus. Environ Microbiol 2018; 20:1158-1169. [DOI: 10.1111/1462-2920.14058] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/07/2018] [Accepted: 01/25/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Xing Zhang
- Institute of Microbiology; Zhejiang University; Hangzhou People's Republic of China
| | | | - Weiguo Fang
- Institute of Microbiology; Zhejiang University; Hangzhou People's Republic of China
- Institute of Insect Sciences; Zhejiang University; Hangzhou People's Republic of China
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