1
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Erdinc D, Rodríguez‐Luis A, Fassad MR, Mackenzie S, Watson CM, Valenzuela S, Xie X, Menger KE, Sergeant K, Craig K, Hopton S, Falkous G, Poulton J, Garcia‐Moreno H, Giunti P, de Moura Aschoff CA, Morales Saute JA, Kirby AJ, Toro C, Wolfe L, Novacic D, Greenbaum L, Eliyahu A, Barel O, Anikster Y, McFarland R, Gorman GS, Schaefer AM, Gustafsson CM, Taylor RW, Falkenberg M, Nicholls TJ. Pathological variants in TOP3A cause distinct disorders of mitochondrial and nuclear genome stability. EMBO Mol Med 2023; 15:e16775. [PMID: 37013609 PMCID: PMC10165364 DOI: 10.15252/emmm.202216775] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
Topoisomerase 3α (TOP3A) is an enzyme that removes torsional strain and interlinks between DNA molecules. TOP3A localises to both the nucleus and mitochondria, with the two isoforms playing specialised roles in DNA recombination and replication respectively. Pathogenic variants in TOP3A can cause a disorder similar to Bloom syndrome, which results from bi-allelic pathogenic variants in BLM, encoding a nuclear-binding partner of TOP3A. In this work, we describe 11 individuals from 9 families with an adult-onset mitochondrial disease resulting from bi-allelic TOP3A gene variants. The majority of patients have a consistent clinical phenotype characterised by bilateral ptosis, ophthalmoplegia, myopathy and axonal sensory-motor neuropathy. We present a comprehensive characterisation of the effect of TOP3A variants, from individuals with mitochondrial disease and Bloom-like syndrome, upon mtDNA maintenance and different aspects of enzyme function. Based on these results, we suggest a model whereby the overall severity of the TOP3A catalytic defect determines the clinical outcome, with milder variants causing adult-onset mitochondrial disease and more severe variants causing a Bloom-like syndrome with mitochondrial dysfunction in childhood.
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Affiliation(s)
- Direnis Erdinc
- Department of Medical Biochemistry and Cell BiologyUniversity of GothenburgGothenburgSweden
| | - Alejandro Rodríguez‐Luis
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Biosciences Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Mahmoud R Fassad
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Sarah Mackenzie
- The Newcastle Upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Christopher M Watson
- North East and Yorkshire Genomic Laboratory Hub, Central LabSt. James's University HospitalLeedsUK
- Leeds Institute of Medical ResearchUniversity of Leeds, St. James's University HospitalLeedsUK
| | - Sebastian Valenzuela
- Department of Medical Biochemistry and Cell BiologyUniversity of GothenburgGothenburgSweden
| | - Xie Xie
- Department of Medical Biochemistry and Cell BiologyUniversity of GothenburgGothenburgSweden
| | - Katja E Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Biosciences Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Kate Sergeant
- Oxford Genetics LaboratoriesOxford University Hospitals NHS Foundation TrustOxfordUK
| | - Kate Craig
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial DisordersNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial DisordersNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial DisordersNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | | | - Joanna Poulton
- Nuffield Department of Women's & Reproductive Health, The Women's CentreUniversity of OxfordOxfordUK
| | - Hector Garcia‐Moreno
- Department of Clinical and Movement Neurosciences, Ataxia CentreUCL Queen Square Institute of NeurologyLondonUK
| | - Paola Giunti
- Department of Clinical and Movement Neurosciences, Ataxia CentreUCL Queen Square Institute of NeurologyLondonUK
| | | | - Jonas A Morales Saute
- Medical Genetics ServiceHospital de Clínicas de Porto Alegre (HCPA)Porto AlegreBrazil
- Department of Internal MedicineUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
- Graduate Program in Medicine: Medical SciencesUniversidade Federal do Rio Grande do SulPorto AlegreBrazil
| | - Amelia J Kirby
- Department of PediatricsWake Forest School of MedicineWinston‐SalemNCUSA
| | - Camilo Toro
- Undiagnosed Diseases ProgramNational Human Genome Research Institute, National Institutes of HealthBethesdaMDUSA
| | - Lynne Wolfe
- Undiagnosed Diseases ProgramNational Human Genome Research Institute, National Institutes of HealthBethesdaMDUSA
| | - Danica Novacic
- Undiagnosed Diseases ProgramNational Human Genome Research Institute, National Institutes of HealthBethesdaMDUSA
| | - Lior Greenbaum
- The Danek Gertner Institute of Human GeneticsSheba Medical CenterTel HashomerIsrael
- The Joseph Sagol Neuroscience Center, Sheba Medical CenterTel HashomerIsrael
- Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Aviva Eliyahu
- The Danek Gertner Institute of Human GeneticsSheba Medical CenterTel HashomerIsrael
- Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
| | - Ortal Barel
- Genomics UnitThe Center for Cancer Research, Sheba Medical CenterTel HashomerIsrael
| | - Yair Anikster
- Sackler Faculty of MedicineTel Aviv UniversityTel AvivIsrael
- Metabolic Disease UnitEdmond and Lily Safra Children's Hospital, Sheba Medical CenterTel HashomerIsrael
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
| | - Andrew M Schaefer
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial DisordersNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell BiologyUniversity of GothenburgGothenburgSweden
- Department of Clinical ChemistrySahlgrenska University HospitalGothenburgSweden
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Translational and Clinical Research Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- NHS Highly Specialised Service for Rare Mitochondrial DisordersNewcastle upon Tyne Hospitals NHS Foundation TrustNewcastle upon TyneUK
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell BiologyUniversity of GothenburgGothenburgSweden
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
- Biosciences Institute, Faculty of Medical SciencesNewcastle UniversityNewcastle upon TyneUK
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2
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Saha LK, Saha S, Yang X, Huang SYN, Sun Y, Jo U, Pommier Y. Replication-associated formation and repair of human topoisomerase IIIα cleavage complexes. Nat Commun 2023; 14:1925. [PMID: 37024461 PMCID: PMC10079683 DOI: 10.1038/s41467-023-37498-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 03/08/2023] [Indexed: 04/08/2023] Open
Abstract
Topoisomerase IIIα (TOP3A) belongs to the conserved Type IA family of DNA topoisomerases. Here we report that human TOP3A is associated with DNA replication forks and that a "self-trapping" TOP3A mutant (TOP3A-R364W) generates cellular TOP3A DNA cleavage complexes (TOP3Accs). We show that trapped TOP3Accs that interfere with replication, induce DNA damage and genome instability. To elucidate how TOP3Accs are repaired, we explored the role of Spartan (SPRTN), the metalloprotease associated with DNA replication, which digests proteins forming DNA-protein crosslinks (DPCs). We find that SPRTN-deficient cells show elevated TOP3Accs, whereas overexpression of SPRTN lowers cellular TOP3Accs. SPRTN is deubiquitinated and epistatic with TDP2 in response to TOP3Accs. In addition, we found that MRE11 can excise TOP3Accs, and that cell cycle determines the preference for the SPRTN-TDP2 vs. the ATM-MRE11 pathways, in S vs. G2, respectively. Our study highlights the prevalence of TOP3Accs repair mechanisms to ensure normal DNA replication.
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Affiliation(s)
- Liton Kumar Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Xi Yang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Shar-Yin Naomi Huang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Yilun Sun
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Ukhyun Jo
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
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3
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Menger KE, Chapman J, Díaz-Maldonado H, Khazeem M, Deen D, Erdinc D, Casement JW, Di Leo V, Pyle A, Rodríguez-Luis A, Cowell I, Falkenberg M, Austin C, Nicholls T. Two type I topoisomerases maintain DNA topology in human mitochondria. Nucleic Acids Res 2022; 50:11154-11174. [PMID: 36215039 PMCID: PMC9638942 DOI: 10.1093/nar/gkac857] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 09/03/2022] [Accepted: 09/26/2022] [Indexed: 11/12/2022] Open
Abstract
Genetic processes require the activity of multiple topoisomerases, essential enzymes that remove topological tension and intermolecular linkages in DNA. We have investigated the subcellular localisation and activity of the six human topoisomerases with a view to understanding the topological maintenance of human mitochondrial DNA. Our results indicate that mitochondria contain two topoisomerases, TOP1MT and TOP3A. Using molecular, genomic and biochemical methods we find that both proteins contribute to mtDNA replication, in addition to the decatenation role of TOP3A, and that TOP1MT is stimulated by mtSSB. Loss of TOP3A or TOP1MT also dysregulates mitochondrial gene expression, and both proteins promote transcription elongation in vitro. We find no evidence for TOP2 localisation to mitochondria, and TOP2B knockout does not affect mtDNA maintenance or expression. Our results suggest a division of labour between TOP3A and TOP1MT in mtDNA topology control that is required for the proper maintenance and expression of human mtDNA.
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Affiliation(s)
- Katja E Menger
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - James Chapman
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Héctor Díaz-Maldonado
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, 405 30 Gothenburg, Sweden
| | - Mushtaq M Khazeem
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Dasha Deen
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Direnis Erdinc
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, 405 30 Gothenburg, Sweden
| | - John W Casement
- Bioinformatics Support Unit, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Valeria Di Leo
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Angela Pyle
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Alejandro Rodríguez-Luis
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Ian G Cowell
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, 405 30 Gothenburg, Sweden
| | - Caroline A Austin
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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4
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Alecki C, Vera M. Role of Nuclear Non-Canonical Nucleic Acid Structures in Organismal Development and Adaptation to Stress Conditions. Front Genet 2022; 13:823241. [PMID: 35281835 PMCID: PMC8906566 DOI: 10.3389/fgene.2022.823241] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/25/2022] [Indexed: 11/21/2022] Open
Abstract
Over the last decades, numerous examples have involved nuclear non-coding RNAs (ncRNAs) in the regulation of gene expression. ncRNAs can interact with the genome by forming non-canonical nucleic acid structures such as R-loops or DNA:RNA triplexes. They bind chromatin and DNA modifiers and transcription factors and favor or prevent their targeting to specific DNA sequences and regulate gene expression of diverse genes. We review the function of these non-canonical nucleic acid structures in regulating gene expression of multicellular organisms during development and in response to different stress conditions and DNA damage using examples described in several organisms, from plants to humans. We also overview recent techniques developed to study where R-loops or DNA:RNA triplexes are formed in the genome and their interaction with proteins.
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Affiliation(s)
- Célia Alecki
- Department of Biochemistry, McGill University, Montreal, QC, Canada
| | - Maria Vera
- Department of Biochemistry, McGill University, Montreal, QC, Canada
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5
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Pommier Y, Nussenzweig A, Takeda S, Austin C. Human topoisomerases and their roles in genome stability and organization. Nat Rev Mol Cell Biol 2022; 23:407-427. [PMID: 35228717 PMCID: PMC8883456 DOI: 10.1038/s41580-022-00452-3] [Citation(s) in RCA: 137] [Impact Index Per Article: 68.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
Human topoisomerases comprise a family of six enzymes: two type IB (TOP1 and mitochondrial TOP1 (TOP1MT), two type IIA (TOP2A and TOP2B) and two type IA (TOP3A and TOP3B) topoisomerases. In this Review, we discuss their biochemistry and their roles in transcription, DNA replication and chromatin remodelling, and highlight the recent progress made in understanding TOP3A and TOP3B. Because of recent advances in elucidating the high-order organization of the genome through chromatin loops and topologically associating domains (TADs), we integrate the functions of topoisomerases with genome organization. We also discuss the physiological and pathological formation of irreversible topoisomerase cleavage complexes (TOPccs) as they generate topoisomerase DNA–protein crosslinks (TOP-DPCs) coupled with DNA breaks. We discuss the expanding number of redundant pathways that repair TOP-DPCs, and the defects in those pathways, which are increasingly recognized as source of genomic damage leading to neurological diseases and cancer. Topoisomerases have essential roles in transcription, DNA replication, chromatin remodelling and, as recently revealed, 3D genome organization. However, topoisomerases also generate DNA–protein crosslinks coupled with DNA breaks, which are increasingly recognized as a source of disease-causing genomic damage.
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6
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Whitbread AL, Dorn A, Röhrig S, Puchta H. Different functional roles of RTR complex factors in DNA repair and meiosis in Arabidopsis and tomato. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:965-977. [PMID: 33619799 DOI: 10.1111/tpj.15211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
The RTR (RecQ/Top3/Rmi1) complex has been elucidated as essential for ensuring genome stability in eukaryotes. Fundamental for the dissolution of Holliday junction (HJ)-like recombination intermediates, the factors have been shown to play further, partly distinct roles in DNA repair and homologous recombination. Across all kingdoms, disruption of this complex results in characteristic phenotypes including hyper-recombination and sensitivity to genotoxins. The type IA topoisomerase TOP3α has been shown as essential for viability in various animals. In contrast, in the model plant species Arabidopsis, the top3α mutant is viable. rmi1 mutants are deficient in the repair of DNA damage. Moreover, as opposed to other eukaryotes, TOP3α and RMI1 were found to be indispensable for proper meiotic progression, with mutants showing severe meiotic defects and sterility. We now established mutants of both TOP3α and RMI1 in tomato using CRISPR/Cas technology. Surprisingly, we found phenotypes that differed dramatically from those of Arabidopsis: the top3α mutants proved to be embryo-lethal, implying an essential role of the topoisomerase in tomato. In contrast, no defect in somatic DNA repair or meiosis was detectable for rmi1 mutants in tomato. This points to a differentiation of function of RTR complex partners between plant species. Our results indicate that there are relevant differences in the roles of basic factors involved in DNA repair and meiosis within dicotyledons, and thus should be taken as a note of caution when generalizing knowledge regarding basic biological processes obtained in the model plant Arabidopsis for the entire plant kingdom.
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Affiliation(s)
- Amy Leanne Whitbread
- Karlsruhe Institute of Technology, Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, 76133, Germany
| | - Annika Dorn
- Karlsruhe Institute of Technology, Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, 76133, Germany
| | - Sarah Röhrig
- Karlsruhe Institute of Technology, Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, 76133, Germany
| | - Holger Puchta
- Karlsruhe Institute of Technology, Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, 76133, Germany
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7
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Abstract
The double-helical structure of genomic DNA is both elegant and functional in that it serves both to protect vulnerable DNA bases and to facilitate DNA replication and compaction. However, these design advantages come at the cost of having to evolve and maintain a cellular machinery that can manipulate a long polymeric molecule that readily becomes topologically entangled whenever it has to be opened for translation, replication, or repair. If such a machinery fails to eliminate detrimental topological entanglements, utilization of the information stored in the DNA double helix is compromised. As a consequence, the use of B-form DNA as the carrier of genetic information must have co-evolved with a means to manipulate its complex topology. This duty is performed by DNA topoisomerases, which therefore are, unsurprisingly, ubiquitous in all kingdoms of life. In this review, we focus on how DNA topoisomerases catalyze their impressive range of DNA-conjuring tricks, with a particular emphasis on DNA topoisomerase III (TOP3). Once thought to be the most unremarkable of topoisomerases, the many lives of these type IA topoisomerases are now being progressively revealed. This research interest is driven by a realization that their substrate versatility and their ability to engage in intimate collaborations with translocases and other DNA-processing enzymes are far more extensive and impressive than was thought hitherto. This, coupled with the recent associations of TOP3s with developmental and neurological pathologies in humans, is clearly making us reconsider their undeserved reputation as being unexceptional enzymes.
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Affiliation(s)
- Anna H Bizard
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
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8
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Zhang T, Wallis M, Petrovic V, Challis J, Kalitsis P, Hudson DF. Loss of TOP3B leads to increased R-loop formation and genome instability. Open Biol 2019; 9:190222. [PMID: 31795919 PMCID: PMC6936252 DOI: 10.1098/rsob.190222] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/01/2019] [Indexed: 12/19/2022] Open
Abstract
Topoisomerase III beta (TOP3B) is one of the least understood members of the topoisomerase family of proteins and remains enigmatic. Our recent data shed light on the function and relevance of TOP3B to disease. A homozygous deletion for the TOP3B gene was identified in a patient with bilateral renal cancer. Analyses in both patient and modelled human cells show the disruption of TOP3B causes genome instability with a rise in DNA damage and chromosome bridging (mis-segregation). The primary molecular defect underlying this pathology is a significant increase in R-loop formation. Our data show that TOP3B is necessary to prevent the accumulation of excessive R-loops and identify TOP3B as a putative cancer gene, and support recent data showing that R-loops are involved in cancer aetiology.
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Affiliation(s)
- Tao Zhang
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Mathew Wallis
- Tasmanian Clinical Genetics Services, Royal Hobart Hospital, Hobart, Tasmania 7001, Australia
- School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Vida Petrovic
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Jackie Challis
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Paul Kalitsis
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Damien F. Hudson
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
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9
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Cox RL, Hofley CM, Tatapudy P, Patel RK, Dayani Y, Betcher M, LaRocque JR. Functional conservation of RecQ helicase BLM between humans and Drosophila melanogaster. Sci Rep 2019; 9:17527. [PMID: 31772289 PMCID: PMC6879748 DOI: 10.1038/s41598-019-54101-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/09/2019] [Indexed: 12/02/2022] Open
Abstract
RecQ helicases are a family of proteins involved in maintaining genome integrity with functions in DNA repair, recombination, and replication. The human RecQ helicase family consists of five helicases: BLM, WRN, RECQL, RECQL4, and RECQL5. Inherited mutations in RecQ helicases result in Bloom Syndrome (BLM mutation), Werner Syndrome (WRN mutation), Rothmund-Thomson Syndrome (RECQL4 mutation), and other genetic diseases, including cancer. The RecQ helicase family is evolutionarily conserved, as Drosophila melanogaster have three family members: DmBlm, DmRecQL4, and DmRecQL5 and DmWRNexo, which contains a conserved exonuclease domain. DmBlm has functional similarities to human BLM (hBLM) as mutants demonstrate increased sensitivity to ionizing radiation (IR) and a decrease in DNA double-strand break (DSB) repair. To determine the extent of functional conservation of RecQ helicases, hBLM was expressed in Drosophila using the GAL4 > UASp system to determine if GAL4 > UASp::hBLM can rescue DmBlm mutant sensitivity to IR. hBLM was able to rescue female DmBlm mutant sensitivity to IR, supporting functional conservation. This functional conservation is specific to BLM, as human GAL4 > UASp::RECQL was not able to rescue DmBlm mutant sensitivity to IR. These results demonstrate the conserved role of BLM in maintaining the genome while reinforcing the applicability of using Drosophila as a model system to study Bloom Syndrome.
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Affiliation(s)
- Rebecca L Cox
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Carolyn M Hofley
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Pallavi Tatapudy
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Romil K Patel
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Yaron Dayani
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Madison Betcher
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Jeannine R LaRocque
- Department of Human Science, Georgetown University Medical Center, Washington, DC, 20057, USA.
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10
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Abstract
DNA topoisomerases are enzymes that catalyze changes in the torsional and flexural strain of DNA molecules. Earlier studies implicated these enzymes in a variety of processes in both prokaryotes and eukaryotes, including DNA replication, transcription, recombination, and chromosome segregation. Studies performed over the past 3 years have provided new insight into the roles of various topoisomerases in maintaining eukaryotic chromosome structure and facilitating the decatenation of daughter chromosomes at cell division. In addition, recent studies have demonstrated that the incorporation of ribonucleotides into DNA results in trapping of topoisomerase I (TOP1)–DNA covalent complexes during aborted ribonucleotide removal. Importantly, such trapped TOP1–DNA covalent complexes, formed either during ribonucleotide removal or as a consequence of drug action, activate several repair processes, including processes involving the recently described nuclear proteases SPARTAN and GCNA-1. A variety of new TOP1 inhibitors and formulations, including antibody–drug conjugates and PEGylated complexes, exert their anticancer effects by also trapping these TOP1–DNA covalent complexes. Here we review recent developments and identify further questions raised by these new findings.
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, 35294-0019, USA
| | - Scott H Kaufmann
- Departments of Oncology and Molecular Pharmacolgy & Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
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11
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Dorn A, Röhrig S, Papp K, Schröpfer S, Hartung F, Knoll A, Puchta H. The topoisomerase 3α zinc-finger domain T1 of Arabidopsis thaliana is required for targeting the enzyme activity to Holliday junction-like DNA repair intermediates. PLoS Genet 2018; 14:e1007674. [PMID: 30222730 PMCID: PMC6160208 DOI: 10.1371/journal.pgen.1007674] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/27/2018] [Accepted: 08/31/2018] [Indexed: 12/18/2022] Open
Abstract
Topoisomerase 3α, a class I topoisomerase, consists of a TOPRIM domain, an active centre and a variable number of zinc-finger domains (ZFDs) at the C-terminus, in multicellular organisms. Whereas the functions of the TOPRIM domain and the active centre are known, the specific role of the ZFDs is still obscure. In contrast to mammals where a knockout of TOP3α leads to lethality, we found that CRISPR/Cas induced mutants in Arabidopsis are viable but show growth retardation and meiotic defects, which can be reversed by the expression of the complete protein. However, complementation with AtTOP3α missing either the TOPRIM-domain or carrying a mutation of the catalytic tyrosine of the active centre leads to embryo lethality. Surprisingly, this phenotype can be overcome by the simultaneous removal of the ZFDs from the protein. In combination with a mutation of the nuclease AtMUS81, the TOP3α knockout proved to be also embryo lethal. Here, expression of TOP3α without ZFDs, and in particular without the conserved ZFD T1, leads to only a partly complementation in root growth-in contrast to the complete protein, that restores root length to mus81-1 mutant level. Expressing the E. coli resolvase RusA in this background, which is able to process Holliday junction (HJ)-like recombination intermediates, we could rescue this root growth defect. Considering all these results, we conclude that the ZFD T1 is specifically required for targeting the topoisomerase activity to HJ like recombination intermediates to enable their processing. In the case of an inactivated enzyme, this leads to cell death due to the masking of these intermediates, hindering their resolution by MUS81.
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Affiliation(s)
- Annika Dorn
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Sarah Röhrig
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Kristin Papp
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Susan Schröpfer
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Frank Hartung
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Alexander Knoll
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Holger Puchta
- Botanical Institute, Molecular Biology and Biochemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
- * E-mail:
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12
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Nicholls TJ, Nadalutti CA, Motori E, Sommerville EW, Gorman GS, Basu S, Hoberg E, Turnbull DM, Chinnery PF, Larsson NG, Larsson E, Falkenberg M, Taylor RW, Griffith JD, Gustafsson CM. Topoisomerase 3α Is Required for Decatenation and Segregation of Human mtDNA. Mol Cell 2017; 69:9-23.e6. [PMID: 29290614 DOI: 10.1016/j.molcel.2017.11.033] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 10/26/2017] [Accepted: 11/26/2017] [Indexed: 01/01/2023]
Abstract
How mtDNA replication is terminated and the newly formed genomes are separated remain unknown. We here demonstrate that the mitochondrial isoform of topoisomerase 3α (Top3α) fulfills this function, acting independently of its nuclear role as a component of the Holliday junction-resolving BLM-Top3α-RMI1-RMI2 (BTR) complex. Our data indicate that mtDNA replication termination occurs via a hemicatenane formed at the origin of H-strand replication and that Top3α is essential for resolving this structure. Decatenation is a prerequisite for separation of the segregating unit of mtDNA, the nucleoid, within the mitochondrial network. The importance of this process is highlighted in a patient with mitochondrial disease caused by biallelic pathogenic variants in TOP3A, characterized by muscle-restricted mtDNA deletions and chronic progressive external ophthalmoplegia (CPEO) plus syndrome. Our work establishes Top3α as an essential component of the mtDNA replication machinery and as the first component of the mtDNA separation machinery.
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Affiliation(s)
- Thomas J Nicholls
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden
| | - Cristina A Nadalutti
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Elisa Motori
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Ewen W Sommerville
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Swaraj Basu
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden
| | - Emily Hoberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Nils-Göran Larsson
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Erik Larsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, 405 30 Gothenburg, Sweden.
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13
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Goto-Ito S, Yamagata A, Takahashi TS, Sato Y, Fukai S. Structural basis of the interaction between Topoisomerase IIIβ and the TDRD3 auxiliary factor. Sci Rep 2017; 7:42123. [PMID: 28176834 PMCID: PMC5296760 DOI: 10.1038/srep42123] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/03/2017] [Indexed: 11/09/2022] Open
Abstract
Topoisomerase IIIβ (TOP3β) is a DNA/RNA topoisomerase that has been implicated in epigenetic or translational control of gene expression. In cells, TOP3β co-exists with its specific auxiliary factor, TDRD3. TDRD3 serves as a scaffold protein to recruit TOP3β to its DNA/RNA substrates accumulating in specific cellular sites such as methylated chromatins or neural stress granules. Here we report the crystal structures of the catalytic domain of TOP3β, the DUF1767–OB-fold domains of TDRD3 and their complex at 3.44 Å, 1.62 Å and 3.6 Å resolutions, respectively. The toroidal-shaped catalytic domain of TOP3β binds the OB-fold domain of TDRD3. The TDRD3 OB-fold domain harbors the insertion loop, which is protruding from the core structure. Both the insertion loop and core region interact with TOP3β. Our pull-down binding assays showed that hydrophobic characters of the core surface and the amino- and carboxy-terminal regions of the insertion loop are essential for the interaction. Furthermore, by comparison with the structure of the homologous Topoisomerase IIIα (TOP3α)–RMI1 complex, we identified Arg96, Val109, Phe139 and the short insertion loop of TDRD3 as the critical structural elements for the specific interaction with TOP3β to avoid the non-cognate interaction with TOP3α.
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Affiliation(s)
- Sakurako Goto-Ito
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan
| | - Atsushi Yamagata
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
| | - Tomio S Takahashi
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan
| | - Yusuke Sato
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
| | - Shuya Fukai
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
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14
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Affiliation(s)
- Giovanni Capranico
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Jessica Marinello
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Giovanni Chillemi
- SCAI
SuperComputing Applications and Innovation Department, Cineca, Via dei Tizii 6, 00185 Rome, Italy
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15
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Multiple mechanisms limit meiotic crossovers: TOP3α and two BLM homologs antagonize crossovers in parallel to FANCM. Proc Natl Acad Sci U S A 2015; 112:4713-8. [PMID: 25825745 DOI: 10.1073/pnas.1423107112] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Meiotic crossovers (COs) have two important roles, shuffling genetic information and ensuring proper chromosome segregation. Despite their importance and a large excess of precursors (i.e., DNA double-strand breaks, DSBs), the number of COs is tightly regulated, typically one to three per chromosome pair. The mechanisms ensuring that most DSBs are repaired as non-COs and the evolutionary forces imposing this constraint are poorly understood. Here we identified Topoisomerase3α (TOP3α) and the RECQ4 helicases--the Arabidopsis slow growth suppressor 1 (Sgs1)/Bloom syndrome protein (BLM) homologs--as major barriers to meiotic CO formation. First, the characterization of a specific TOP3α mutant allele revealed that, in addition to its role in DNA repair, this topoisomerase antagonizes CO formation. Further, we found that RECQ4A and RECQ4B constitute the strongest meiotic anti-CO activity identified to date, their concomitant depletion leading to a sixfold increase in CO frequency. In both top3α and recq4ab mutants, DSB number is unaffected, and extra COs arise from a normally minor pathway. Finally, both TOP3α and RECQ4A/B act independently of the previously identified anti-CO Fanconi anemia of complementation group M (FANCM) helicase. This finding shows that several parallel pathways actively limit CO formation and suggests that the RECQA/B and FANCM helicases prevent COs by processing different substrates. Despite a ninefold increase in CO frequency, chromosome segregation was unaffected. This finding supports the idea that CO number is restricted not because of mechanical constraints but likely because of the long-term costs of recombination. Furthermore, this work demonstrates how manipulating a few genes holds great promise for increasing recombination frequency in plant-breeding programs.
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Abstract
Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions.
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Affiliation(s)
- Anna H Bizard
- Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Ian D Hickson
- Nordea Center for Healthy Aging, Department of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, 2200 Copenhagen N, Denmark
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17
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Synthesis and dissolution of hemicatenanes by type IA DNA topoisomerases. Proc Natl Acad Sci U S A 2013; 110:E3587-94. [PMID: 24003117 DOI: 10.1073/pnas.1304103110] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Type IA DNA topoisomerases work with a unique mechanism of strand passage through an enzyme-bridged, ssDNA gate, thus enabling them to carry out diverse reactions in processing structures important for replication, recombination, and repair. Here we report a unique reaction mediated by an archaeal type IA topoisomerase, the synthesis and dissolution of hemicatenanes. We cloned, purified, and characterized an unusual type IA enzyme from a hyperthermophilic archaeum, Nanoarchaeum equitans, which is split into two pieces. The recombinant heterodimeric enzyme has the expected activities in its preference of relaxing negatively supercoiled DNA. Its amino acid sequence and cleavage site sequence analysis suggest that it is topoisomerase III, and therefore we named it "NeqTop3." At high enzyme concentrations, NeqTop3 can generate high-molecular-weight DNA networks. Biochemical and electron microscopic data indicate that the DNA networks are connected through hemicatenane linkages. The hemicatenane formation likely is mediated by the single-strand passage through denatured bubbles in the substrate DNA under high temperature. NeqTop3 at lower concentrations can reverse hemicatenanes. A complex of human topoisomerase 3α, Bloom helicase, and RecQ-mediated genome instability protein 1 and 2 can partially disentangle the hemicatenane network. Both the formation and dissolution of hemicatenanes by type IA topoisomerases demonstrate that these enzymes have an important role in regulating intermediates from replication, recombination, and repair.
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18
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Top3β is an RNA topoisomerase that works with fragile X syndrome protein to promote synapse formation. Nat Neurosci 2013; 16:1238-47. [PMID: 23912945 PMCID: PMC3853347 DOI: 10.1038/nn.3479] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 06/21/2013] [Indexed: 12/11/2022]
Abstract
Topoisomerases are crucial to solve DNA topological problems, but they have not been linked to RNA metabolism. Here we show that human topoisomerase 3β (Top3β) is an RNA topoisomerase that biochemically and genetically interacts with FMRP, a protein deficient in Fragile X syndrome and known to regulate translation of mRNAs important for neuronal function and autism. Notably, the FMRP-Top3β interaction is abolished by a disease-associated FMRP mutation, suggesting that Top3β may contribute to pathogenesis of mental disorders. Top3β binds multiple mRNAs encoded by genes with neuronal functions related to schizophrenia and autism. Expression of one such gene, ptk2/FAK, is reduced in neuromuscular junctions of Top3β mutant flies. Synapse formation is defective in Top3β mutant flies and mice, as observed in FMRP mutant animals. Our findings suggest that Top3β acts as an RNA topoisomerase and works with FMRP to promote expression of mRNAs critical for neurodevelopment and mental health.
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19
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Chen SH, Chan NL, Hsieh TS. New mechanistic and functional insights into DNA topoisomerases. Annu Rev Biochem 2013; 82:139-70. [PMID: 23495937 DOI: 10.1146/annurev-biochem-061809-100002] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA topoisomerases are nature's tools for resolving the unique problems of DNA entanglement that occur owing to unwinding and rewinding of the DNA helix during replication, transcription, recombination, repair, and chromatin remodeling. These enzymes perform topological transformations by providing a transient DNA break, formed by a covalent adduct with the enzyme, through which strand passage can occur. The active site tyrosine is responsible for initiating two transesterifications to cleave and then religate the DNA backbone. The cleavage reaction intermediate is exploited by cytotoxic agents, which have important applications as antibiotics and anticancer drugs. The reactions mediated by these enzymes can also be regulated by their binding partners; one example is a DNA helicase capable of modulating the directionality of strand passage, enabling important functions like reannealing denatured DNA and resolving recombination intermediates. In this review, we cover recent advances in mechanistic insights into topoisomerases and their various cellular functions.
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Affiliation(s)
- Stefanie Hartman Chen
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
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20
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Chen SH, Wu CH, Plank JL, Hsieh TS. Essential functions of C terminus of Drosophila Topoisomerase IIIα in double holliday junction dissolution. J Biol Chem 2012; 287:19346-53. [PMID: 22511792 DOI: 10.1074/jbc.m112.363044] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Topoisomerase IIIα (Top3α) is an essential component of the double Holliday junction (dHJ) dissolvasome complex in metazoans, along with Blm and Rmi1/2. This important anti-recombinogenic function cannot be performed by Top3β, the other type IA topoisomerase present in metazoans. The two share a catalytic core but diverge in their tail regions. To understand this difference in function, we investigated the role of the unique C terminus of Top3α. The Drosophila C terminus contains an insert region not conserved among metazoans. This insert contributes an independent interaction with Blm, which may account for the absence of Rmi1 in Drosophila. Mutant Top3α lacking this insert maintains the ability to perform dHJ dissolution but only partially rescues a top3α null fly line, indicating an in vivo role for the insert. Truncation of the C terminus has a minimal effect on the type IA relaxation activity of Top3α; however, dHJ dissolution is greatly reduced. The Top3α C terminus was found to strongly interact with both Blm and DNA, which are critical to the dissolution reaction; these interactions are greatly reduced in the truncated enzyme. The truncation mutant also cannot rescue the viability of top3α null flies, indicating an essential in vivo role. Our data therefore suggest that the Top3α C terminus has an important role in dHJ dissolution (by providing an interaction interface for Blm and DNA) and an essential function in vivo.
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21
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Yang J, Bachrati CZ, Hickson ID, Brown GW. BLM and RMI1 alleviate RPA inhibition of TopoIIIα decatenase activity. PLoS One 2012; 7:e41208. [PMID: 22911760 PMCID: PMC3401101 DOI: 10.1371/journal.pone.0041208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Accepted: 06/18/2012] [Indexed: 11/29/2022] Open
Abstract
RPA is a single-stranded DNA binding protein that physically associates with the BLM complex. RPA stimulates BLM helicase activity as well as the double Holliday junction dissolution activity of the BLM-topoisomerase IIIα complex. We investigated the effect of RPA on the ssDNA decatenase activity of topoisomerase IIIα. We found that RPA and other ssDNA binding proteins inhibit decatenation by topoisomerase IIIα. Complex formation between BLM, TopoIIIα, and RMI1 ablates inhibition of decatenation by ssDNA binding proteins. Together, these data indicate that inhibition by RPA does not involve species-specific interactions between RPA and BLM-TopoIIIα-RMI1, which contrasts with RPA modulation of double Holliday junction dissolution. We propose that topoisomerase IIIα and RPA compete to bind to single-stranded regions of catenanes. Interactions with BLM and RMI1 enhance toposiomerase IIIα activity, promoting decatenation in the presence of RPA.
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Affiliation(s)
- Jay Yang
- Department of Biochemistry and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Csanad Z. Bachrati
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Ian D. Hickson
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Grant W. Brown
- Department of Biochemistry and Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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22
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Abstract
To maintain tissue homeostasis, some organs are able to replace dying cells with additional proliferation of surviving cells. Such proliferation can be localized (e.g., a regeneration blastema) or diffuse (compensatory growth). The relationship between such growth and the growth that occurs during development has not been characterized in detail. Drosophila melanogaster larval imaginal discs can recover from extensive damage, producing normally sized adult organs. Here we describe a system using genetic mosaics to screen for recessive mutations that impair compensatory growth. By generating clones of cells that carry a temperature-sensitive cell-lethal mutation, we conditionally ablate patches of tissue in the imaginal disc and assess the ability of the surviving sister clones to replace the lost tissue. We have used this system together with a modified whole-genome resequencing (WGS) strategy to identify several mutations that selectively compromise compensatory growth. We find specific alleles of bunched (bun) and Ribonucleoside diphosphate reductase large subunit (RnrL) reduce compensatory growth in the imaginal disc. Other genes identified in the screen, including two alleles of Topoisomerase 3-alpha (Top3α), while also required for developmental growth, appear to have an enhanced requirement during compensatory growth. Compensatory growth occurs at a higher rate than normal growth and may therefore have features in common with some types of overgrowth. Indeed, the RnrL allele identified compromises both these types of altered growth and mammalian ribonucleotide reductase and topoisomerases are targets of anticancer drugs. Finally, the approach we describe is applicable to the study of compensatory growth in diverse tissues in Drosophila.
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Rmi1 stimulates decatenation of double Holliday junctions during dissolution by Sgs1-Top3. Nat Struct Mol Biol 2010; 17:1377-82. [PMID: 20935631 PMCID: PMC2988882 DOI: 10.1038/nsmb.1919] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 08/30/2010] [Indexed: 11/23/2022]
Abstract
A double Holliday junction (dHJ) is a central intermediate of homologous recombination which can be processed to yield crossover or non-crossover recombination products. To preserve genomic integrity, cells possess mechanisms to avoid crossing-over. Here we show that Saccharomyces cerevisiae Sgs1 and Top3 proteins are sufficient to migrate and disentangle a dHJ to produce exclusively non-crossover recombination products, in a reaction termed “dissolution”. Furthermore, we show that Rmi1 stimulates dHJ dissolution at low Sgs1–Top3 protein concentrations, although it has no effect on the initial rate of Holliday junction (HJ) migration. Rmi1 serves to stimulate DNA decatenation, thereby removing the last linkages between the repaired and template DNA molecules. Dissolution of a dHJ is a highly efficient and concerted alternative to nucleolytic resolution that prevents crossing over of chromosomes during recombinational DNA repair in mitotic cells, and thereby contributes to genomic integrity.
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Drosophila topo IIIalpha is required for the maintenance of mitochondrial genome and male germ-line stem cells. Proc Natl Acad Sci U S A 2010; 107:6228-33. [PMID: 20308575 DOI: 10.1073/pnas.1001855107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Topoisomerase IIIalpha (topo IIIalpha), a member of the conserved Type IA subfamily of topoisomerases, is required for the cell proliferation in mitotic tissues, but has a lesser effect on DNA endoreplication. The top3alpha gene encodes two forms of protein by utilizing alternative translation initiation sites: one (short form) with the nuclear localization signal only, exclusively localized in the nuclei, and the other (long form), retaining a mitochondrial import sequence at the N-terminus and the nuclear localization sequence at the C-terminus, localized primarily in the mitochondria, though with a small portion in the nuclei. Both forms of topo IIIalpha can rescue the viability of null mutants of top3alpha. No apparent defect is associated with the flies rescued by the long form; short-form-rescued flies (referred to as M1L), however, exhibit defects in fertilities. M1L females are sterile. They can lay eggs but with mitochondrial DNA (mtDNA) copy number and ATP content decreased by 20- and 2- to 3-fold, respectively, and they fail to hatch. Of the newly eclosed M1L males, 33% are completely sterile, whereas the rest have residual fertilities that are quickly lost in 6 days. The fertility loss of M1L males is caused by the disruption of the individualization complex and a progressive loss of germ-line stem cells. This study implicates topo IIIalpha in the maintenance of mtDNA and male germ-line stem cells, and thus is a causative candidate for genetic disorders associated with mtDNA depletion.
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25
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Animal models of mitochondrial DNA transactions in disease and ageing. Exp Gerontol 2010; 45:489-502. [PMID: 20123011 DOI: 10.1016/j.exger.2010.01.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Revised: 01/11/2010] [Accepted: 01/26/2010] [Indexed: 11/21/2022]
Abstract
Mitochondrial DNA (mtDNA) transactions, processes that include mtDNA replication, repair, recombination and transcription constitute the initial stages of mitochondrial biogenesis, and are at the core of understanding mitochondrial biology and medicine. All of the protein players are encoded in nuclear genes: some are proteins with well-known functions in the nucleus, others are well-known mitochondrial proteins now ascribed new functions, and still others are newly discovered factors. In this article we review recent advances in the field of mtDNA transactions with a special focus on physiological studies. In particular, we consider the expression of variant proteins, or altered expression of factors involved in these processes in powerful model organisms, such as Drosophila melanogaster and the mouse, which have promoted recognition of the broad relevance of oxidative phosphorylation defects resulting from improper maintenance of mtDNA. Furthermore, the animal models recapitulate many phenotypes related to human ageing and a variety of different diseases, a feature that has enhanced our understanding of, and inspired theories about, the molecular mechanisms of such biological processes.
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Wang X, Huang Y, Lavrov DV, Gu X. Comparative study of human mitochondrial proteome reveals extensive protein subcellular relocalization after gene duplications. BMC Evol Biol 2009; 9:275. [PMID: 19948060 PMCID: PMC2790464 DOI: 10.1186/1471-2148-9-275] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 11/30/2009] [Indexed: 11/10/2022] Open
Abstract
Background Gene and genome duplication is the principle creative force in evolution. Recently, protein subcellular relocalization, or neolocalization was proposed as one of the mechanisms responsible for the retention of duplicated genes. This hypothesis received support from the analysis of yeast genomes, but has not been tested thoroughly on animal genomes. In order to evaluate the importance of subcellular relocalizations for retention of duplicated genes in animal genomes, we systematically analyzed nuclear encoded mitochondrial proteins in the human genome by reconstructing phylogenies of mitochondrial multigene families. Results The 456 human mitochondrial proteins selected for this study were clustered into 305 gene families including 92 multigene families. Among the multigene families, 59 (64%) consisted of both mitochondrial and cytosolic (non-mitochondrial) proteins (mt-cy families) while the remaining 33 (36%) were composed of mitochondrial proteins (mt-mt families). Phylogenetic analyses of mt-cy families revealed three different scenarios of their neolocalization following gene duplication: 1) relocalization from mitochondria to cytosol, 2) from cytosol to mitochondria and 3) multiple subcellular relocalizations. The neolocalizations were most commonly enabled by the gain or loss of N-terminal mitochondrial targeting signals. The majority of detected subcellular relocalization events occurred early in animal evolution, preceding the evolution of tetrapods. Mt-mt protein families showed a somewhat different pattern, where gene duplication occurred more evenly in time. However, for both types of protein families, most duplication events appear to roughly coincide with two rounds of genome duplications early in vertebrate evolution. Finally, we evaluated the effects of inaccurate and incomplete annotation of mitochondrial proteins and found that our conclusion of the importance of subcellular relocalization after gene duplication on the genomic scale was robust to potential gene misannotation. Conclusion Our results suggest that protein subcellular relocalization is an important mechanism for the retention and gain of function of duplicated genes in animal genome evolution.
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Affiliation(s)
- Xiujuan Wang
- Interdepartmental Genetics Program, Iowa State University, Ames, IA 50011, USA.
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Plank J, Hsieh TS. Helicase-appended topoisomerases: new insight into the mechanism of directional strand transfer. J Biol Chem 2009; 284:30737-41. [PMID: 19726668 DOI: 10.1074/jbc.r109.051268] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA strand passage through an enzyme-mediated gate is a key step in the catalytic cycle of topoisomerases to produce topological transformations in DNA. In most of the reactions catalyzed by topoisomerases, strand passage is not directional; thus, the enzyme simply provides a transient DNA gate through which DNA transport is allowed and thereby resolves the topological entanglement. When studied in isolation, the type IA topoisomerase family appears to conform to this rule. Interestingly, type IA enzymes can carry out directional strand transport as well. We examined here the biochemical mechanism for directional strand passage of two type IA topoisomerases: reverse gyrase and a protein complex of topoisomerase III alpha and Bloom helicase. These enzymes are able to generate vectorial strand transport independent of the supercoiling energy stored in the DNA molecule. Reverse gyrase is able to anneal single strands, thereby increasing linkage number of a DNA molecule. However, topoisomerase III alpha and Bloom helicase can dissolve DNA conjoined with a double Holliday junction, thus reducing DNA linkage. We propose here that the helicase or helicase-like component plays a determinant role in the directionality of strand transport. There is thus a common biochemical ground for the directional strand passage for the type IA topoisomerases.
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Affiliation(s)
- Jody Plank
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Hartung F, Suer S, Knoll A, Wurz-Wildersinn R, Puchta H. Topoisomerase 3alpha and RMI1 suppress somatic crossovers and are essential for resolution of meiotic recombination intermediates in Arabidopsis thaliana. PLoS Genet 2008; 4:e1000285. [PMID: 19096507 PMCID: PMC2588661 DOI: 10.1371/journal.pgen.1000285] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 10/28/2008] [Indexed: 11/18/2022] Open
Abstract
Topoisomerases are enzymes with crucial functions in DNA metabolism. They are ubiquitously present in prokaryotes and eukaryotes and modify the steady-state level of DNA supercoiling. Biochemical analyses indicate that Topoisomerase 3α (TOP3α) functions together with a RecQ DNA helicase and a third partner, RMI1/BLAP75, in the resolution step of homologous recombination in a process called Holliday Junction dissolution in eukaryotes. Apart from that, little is known about the role of TOP3α in higher eukaryotes, as knockout mutants show early lethality or strong developmental defects. Using a hypomorphic insertion mutant of Arabidopsis thaliana (top3α-2), which is viable but completely sterile, we were able to define three different functions of the protein in mitosis and meiosis. The top3α-2 line exhibits fragmented chromosomes during mitosis and sensitivity to camptothecin, suggesting an important role in chromosome segregation partly overlapping with that of type IB topoisomerases. Furthermore, AtTOP3α, together with AtRECQ4A and AtRMI1, is involved in the suppression of crossover recombination in somatic cells as well as DNA repair in both mammals and A. thaliana. Surprisingly, AtTOP3α is also essential for meiosis. The phenotype of chromosome fragmentation, bridges, and telophase I arrest can be suppressed by AtSPO11 and AtRAD51 mutations, indicating that the protein is required for the resolution of recombination intermediates. As Atrmi1 mutants have a similar meiotic phenotype to Attop3α mutants, both proteins seem to be involved in a mechanism safeguarding the entangling of homologous chromosomes during meiosis. The requirement of AtTOP3α and AtRMI1 in a late step of meiotic recombination strongly hints at the possibility that the dissolution of double Holliday Junctions via a hemicatenane intermediate is indeed an indispensable step of meiotic recombination. The topoisomerases of the class IA are present in all three eukaryotic kingdoms—plants, fungi, and animals—and are involved in DNA replication and DNA repair. During the course of their action, they introduce transient single-strand nicks into DNA. In higher eukaryotes, two different classes of the enzymes are present: TOP3α and TOP3β. TOP3α is essential, as disruption of its function usually results in lethality of the affected organism. Using a mutant of TOP3α that retains some activity, we show that the protein has multiple, different functions in the model plant A. thaliana. Besides its action in somatic cells, where it is required for mitosis as well as DNA repair, we demonstrate that TOP3α together with its protein partner RMI1 is essential for meiosis. Here, both proteins are involved in DNA recombination—the exchange of information between parental chromosomes. Disruption of either TOP3α or RMI1 leads to grave defects and an early termination of meiosis, resulting in the sterility of the mutant plants. Our detailed analysis indicates that both proteins are involved in a late step of meiotic recombination, in a mechanism that prevents entanglement of the parental chromosomes. Thus, meiotic recombination seems to be more complex than previously anticipated.
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Affiliation(s)
- Frank Hartung
- Botany II, University of Karlsruhe, Karlsruhe, Germany
| | - Stefanie Suer
- Botany II, University of Karlsruhe, Karlsruhe, Germany
| | | | | | - Holger Puchta
- Botany II, University of Karlsruhe, Karlsruhe, Germany
- * E-mail:
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Webb MR, Plank JL, Long DT, Hsieh TS, Kreuzer KN. The phage T4 protein UvsW drives Holliday junction branch migration. J Biol Chem 2007; 282:34401-11. [PMID: 17823128 PMCID: PMC2094049 DOI: 10.1074/jbc.m705913200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phage T4 UvsW protein has been shown to play a crucial role in the switch from origin-dependent to recombination-dependent replication in T4 infections through the unwinding of origin R-loop initiation intermediates. UvsW also functions with UvsX and UvsY to repair damaged DNA through homologous recombination, and, based on genetic evidence, has been proposed to act as a Holliday junction branch migration enzyme. Here we report the purification and characterization of UvsW. Using oligonucleotide-based substrates, we confirm that UvsW unwinds branched DNA substrates, including X and Y structures, but shows little activity in unwinding linear duplex substrates with blunt or single-strand ends. Using a novel Holliday junction-containing substrate, we also demonstrate that UvsW promotes the branch migration of Holliday junctions efficiently through more than 1000 bp of DNA. The ATP hydrolysis-deficient mutant protein, UvsW-K141R, is unable to promote Holliday junction branch migration. However, both UvsW and UvsW-K141R are capable of stabilizing Holliday junctions against spontaneous branch migration when ATP is not present. Using two-dimensional agarose gel electrophoresis we also show that UvsW acts on T4-generated replication intermediates, including Holliday junction-containing X-shaped intermediates and replication fork-shaped intermediates. Taken together, these results strongly support a role for UvsW in the branch migration of Holliday junctions that form during T4 recombination, replication, and repair.
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Affiliation(s)
- Michael R Webb
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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30
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Abstract
Rmi1 is a conserved oligonucleotide and oligosaccharide binding-fold protein that is associated with RecQ DNA helicase complexes from humans (BLM-TOP3 alpha) and yeast (Sgs1-Top3). Although human RMI1 stimulates the dissolution activity of BLM-TOP3 alpha, its biochemical function is unknown. Here we examined the role of Rmi1 in the yeast complex. Consistent with the similarity of top3Delta and rmi1Delta phenotypes, we find that a stable Top3.Rmi1 complex can be isolated from yeast cells overexpressing these two subunits. Compared with Top3 alone, this complex displays increased superhelical relaxation activity. The isolated Rmi1 subunit also stimulates Top3 activity in reconstitution experiments. In both cases elevated temperatures are required for optimal relaxation unless the substrate contains a single-strand DNA (ssDNA) bubble. Interestingly, Rmi1 binds only weakly to ssDNA on its own, but it stimulates the ssDNA binding activity of Top3 5-fold. Top3 and Rmi1 also cooperate to bind the Sgs1 N terminus and promote its interaction with ssDNA. These results demonstrate that Top3-Rmi1 functions as a complex and suggest that Rmi1 stimulates Top3 by promoting its interaction with ssDNA.
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Affiliation(s)
- Chi-Fu Chen
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854
| | - Steven J Brill
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854.
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31
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Zhang H, Meng LH, Pommier Y. Mitochondrial topoisomerases and alternative splicing of the human TOP1mt gene. Biochimie 2007; 89:474-81. [PMID: 17161897 DOI: 10.1016/j.biochi.2006.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 11/07/2006] [Indexed: 11/20/2022]
Abstract
Mitochondria are the only organelles containing metabolically active DNA besides nuclei. By analogy with the nuclear topoisomerases, mitochondrial topoisomerase activities are probably critical for maintaining the topology of mitochondrial DNA during replication, transcription, and repair. Mitochondrial diseases include a wide range of defects including neurodegeneracies, myopathies, metabolic abnormalities and premature aging. Vertebrates only have one known specific mitochondrial topoisomerase gene (TOP1mt), coding for a type IB topoisomerase. Like the mitochondrial DNA and RNA polymerase, the TOP1mt gene is encoded in the nuclear genome. The TOP1mt gene possesses the 13 exon Top1B signature motif and codes for a mitochondrial targeting signals at the N-terminus of the Top1mt polypeptide. This review summarizes our current knowledge of mitochondrial topoisomerases (type IA, IB and type II) in eukaryotes including budding and fission yeasts (Saccharomyces cerevisiae and Schizosaccharomyces pombe) and protozoan parasites (kinetoplastidiae and plasmodium). It also includes new data showing alternative splice variants of human TOP1mt.
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Affiliation(s)
- Hongliang Zhang
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg 37, Room 5068, Bethesda, MD 20892-4255, USA
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32
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Johnson-Schlitz DM, Flores C, Engels WR. Multiple-pathway analysis of double-strand break repair mutations in Drosophila. PLoS Genet 2007; 3:e50. [PMID: 17432935 PMCID: PMC1851981 DOI: 10.1371/journal.pgen.0030050] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Accepted: 02/20/2007] [Indexed: 11/19/2022] Open
Abstract
The analysis of double-strand break (DSB) repair is complicated by the existence of several pathways utilizing a large number of genes. Moreover, many of these genes have been shown to have multiple roles in DSB repair. To address this complexity we used a repair reporter construct designed to measure multiple repair outcomes simultaneously. This approach provides estimates of the relative usage of several DSB repair pathways in the premeiotic male germline of Drosophila. We applied this system to mutations at each of 11 repair loci plus various double mutants and altered dosage genotypes. Most of the mutants were found to suppress one of the pathways with a compensating increase in one or more of the others. Perhaps surprisingly, none of the single mutants suppressed more than one pathway, but they varied widely in how the suppression was compensated. We found several cases in which two or more loci were similar in which pathway was suppressed while differing in how this suppression was compensated. Taken as a whole, the data suggest that the choice of which repair pathway is used for a given DSB occurs by a two-stage "decision circuit" in which the DSB is first placed into one of two pools from which a specific pathway is then selected.
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Affiliation(s)
- Dena M Johnson-Schlitz
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Carlos Flores
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
| | - William R Engels
- Department of Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
- * To whom correspondence should be addressed. E-mail:
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Johnson-Schlitz D, Engels WR. Template disruptions and failure of double Holliday junction dissolution during double-strand break repair in Drosophila BLM mutants. Proc Natl Acad Sci U S A 2006; 103:16840-5. [PMID: 17075047 PMCID: PMC1636541 DOI: 10.1073/pnas.0607904103] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Previous biochemical studies of the BLM gene product have shown its ability in conjunction with topoisomerase IIIalpha to resolve double Holliday structures through a process called "dissolution." This process could prevent crossing over during repair of double-strand breaks. We report an analysis of the Drosophila BLM gene, DmBlm, in the repair of double-strand breaks in the premeiotic germ line of Drosophila males. With a repair reporter construct, Rr3, and other genetic tools, we show that DmBlm mutants are defective for homologous repair but show a compensating increase in single-strand annealing. Increases of 40- to 50-fold in crossing over and flanking deletions also were seen. Perhaps most significantly, the template used for homologous repair in DmBlm mutants is itself subject to deletions and complex rearrangements. These template disruptions are indicative of failure to resolve double Holliday junctions. These findings, along with the demonstration that a weak allele of topoisomerase IIIalpha has some of the same defects as DmBlm, support the dissolution model. Finally, an analysis of DmBlm mutants in conjunction with mus81 or spnA (Rad51) reveals a second function of BLM distinct from the repair of induced double-strand breaks and possibly related to maintenance of replication forks.
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Affiliation(s)
| | - William R. Engels
- Genetics Department, University of Wisconsin, Madison, WI 53706
- To whom correspondence should be addressed. E-mail:
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34
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Plank JL, Wu J, Hsieh TS. Topoisomerase IIIalpha and Bloom's helicase can resolve a mobile double Holliday junction substrate through convergent branch migration. Proc Natl Acad Sci U S A 2006; 103:11118-23. [PMID: 16849422 PMCID: PMC1544052 DOI: 10.1073/pnas.0604873103] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has long been suspected that a double Holliday junction (dHJ) could be resolved by a topoisomerase partnered with a helicase by convergent branch migration of the HJs. Genetic analysis of yeast TOP3 and SGS1 has lent considerable evidence to the notion that the protein products of these genes are involved in just such a process, although biochemical analysis of the metabolism of a dHJ has been hindered by the lack of a substrate that adequately replicates the endogenous structure. We have synthesized a dHJ substrate that recapitulates many of the features of an endogenous dHJ and represents a much earlier intermediate in the resolution pathway. Here, we show that Drosophila topoisomerase IIIalpha (Topo IIIalpha) and Blm (a homolog of Sgs1) are capable of resolving this substrate to non-cross-over products and that this activity is stimulated by replication protein A (RPA). We investigated the ability of other Drosophila topoisomerases to perform this reaction in concert with Blm and RPA and discovered that this resolution activity is unique to Topo IIIalpha. Examination of the mechanism of resolution reveals that Topo IIIalpha, Blm, and RPA resolve this substrate by convergent migration of the two HJs toward each other, collapsing the dHJ. This mechanism stands in contrast to classic resolvase activities that use a structure-specific endonuclease to cleave the HJs.
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Affiliation(s)
- Jody L. Plank
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Jianhong Wu
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Tao-shih Hsieh
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
- *To whom correspondence should be addressed at:
Department of Biochemistry, Duke University Medical Center, DUMC Box 3711, Durham, NC 27710. E-mail:
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35
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Plank JL, Hsieh TS. A novel, topologically constrained DNA molecule containing a double Holliday junction: design, synthesis, and initial biochemical characterization. J Biol Chem 2006; 281:17510-17516. [PMID: 16608853 PMCID: PMC2041448 DOI: 10.1074/jbc.m602933200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The double Holliday junction (dHJ) is a central intermediate to homologous recombination, but biochemical analysis of the metabolism of this structure has been hindered by the lack of a substrate that adequately replicates the endogenous structure. We have synthesized a novel dHJ substrate that consists of two small, double stranded DNA circles conjoined by two Holliday junctions (HJs). Its biochemical synthesis is based on the production of two pairs of single stranded circles from phagemids, followed by their sequential annealing with reverse gyrase. The sequence between the two HJs is identical on both strands, allowing the HJs to migrate without the generation of unpaired regions of DNA, whereas the distance between the HJs is on the order of gene conversion tracts thus far measured in Drosophila and mouse model systems. The structure of this substrate also provides similar topological constraint as would occur in an endogenous dHJ. Digestion of the dHJ substrate by T7 endonuclease I resolves the substrate into crossover and non-crossover products, as predicted by the Szostak model of double strand break repair. This substrate will greatly facilitate the examination of the mechanism of resolution of double Holliday junctions.
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Affiliation(s)
- Jody L Plank
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710
| | - Tao-Shih Hsieh
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
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Hsieh TS, Plank JL. Reverse gyrase functions as a DNA renaturase: annealing of complementary single-stranded circles and positive supercoiling of a bubble substrate. J Biol Chem 2006; 281:5640-7. [PMID: 16407212 DOI: 10.1074/jbc.m513252200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reverse gyrase is a hyperthermophile-specific enzyme that can positively supercoil DNA concomitant with ATP hydrolysis. However, the DNA supercoiling activity is inefficient and requires an excess amount of enzyme relative to DNA. We report here several activities that reverse gyrase can efficiently mediate with a substoichiometric amount of enzyme. In the presence of a nucleotide cofactor, reverse gyrase can readily relax negative supercoils, but not the positive ones, from a plasmid DNA substrate. Reverse gyrase can completely relax positively supercoiled DNA, provided that the DNA substrate contains a single-stranded bubble. Reverse gyrase efficiently anneals complementary single-stranded circles. A substoichiometric amount of reverse gyrase can insert positive supercoils into DNA with a single-stranded bubble, in contrast to plasmid DNA substrate. We have designed a novel method based on phage-mid DNA vectors to prepare a circular DNA substrate containing a single-stranded bubble with defined length and sequence. With these bubble DNA substrates, we demonstrated that efficient positive supercoiling by reverse gyrase requires a bubble size larger than 20 nucleotides. The activities of annealing single-stranded DNA circles and positive supercoiling of bubble substrate demonstrate that reverse gyrase can function as a DNA renaturase. These biochemical activities also suggest that reverse gyrase can have an important biological function in sensing and eliminating unpaired regions in the genome of a hyperthermophilic organism.
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Affiliation(s)
- Tao-shih Hsieh
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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Hsieh TS, Capp C. Nucleotide- and stoichiometry-dependent DNA supercoiling by reverse gyrase. J Biol Chem 2005; 280:20467-75. [PMID: 15788400 DOI: 10.1074/jbc.m502739200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reverse gyrase is a unique type IA topoisomerase that can introduce positive supercoils into DNA. We have investigated some of the biochemical properties of Archaeoglobus fulgidus reverse gyrase. It can mediate three distinct supercoiling reactions depending on the adenine nucleotide cofactor that is present in the reaction. Besides the ATP-driven positive supercoiling reaction, the enzyme can introduce negative supercoils with a nonhydrolyzable analog, adenylyl imidodiphosphate. In the presence of ADP the plasmid DNA is relaxed almost completely, leaving a very low level of positive supercoiling. Surprisingly, the final supercoiling extent for all three distinct reactions depends on the stoichiometry of enzyme to DNA. This dependence is not due to the difference of reaction rate, suggesting that the amount of enzyme bound to DNA is an important determinant for the final supercoiling state of the reaction product. Reverse gyrase also displays exquisite sensitivity toward temperature. Raising the reaction temperatures from 80 to 85 degrees C, both of which are within the optimal growth temperature of A. fulgidus, greatly increases enzyme activity for all the supercoiling reactions. For the reaction with AMPPNP, the product is a hypernegatively supercoiled DNA. This dramatic enhancement of the reverse gyrase activity is also correlated with the appearance of DNA in a pre-melting state at 85 degrees C, likely due to the presence of extensively unwound regions in the plasmid. The possible mechanistic insights from these findings will be presented here.
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Affiliation(s)
- Tao-shih Hsieh
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
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