1
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Zhang H, Sun Y, Saha S, Saha LK, Pongor LS, Dhall A, Pommier Y. Genome-wide Mapping of Topoisomerase Binding Sites Suggests Topoisomerase 3α (TOP3A) as a Reader of Transcription-Replication Conflicts (TRC). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.17.599352. [PMID: 38948815 PMCID: PMC11212928 DOI: 10.1101/2024.06.17.599352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Both transcription and replication can take place simultaneously on the same DNA template, potentially leading to transcription-replication conflicts (TRCs) and topological problems. Here we asked which topoisomerase(s) is/are the best candidate(s) for sensing TRC. Genome-wide topoisomerase binding sites were mapped in parallel for all the nuclear topoisomerases (TOP1, TOP2A, TOP2B, TOP3A and TOP3B). To increase the signal to noise ratio (SNR), we used ectopic expression of those topoisomerases in H293 cells followed by a modified CUT&Tag method. Although each topoisomerase showed distinct binding patterns, all topoisomerase binding signals positively correlated with gene transcription. TOP3A binding signals were suppressed by DNA replication inhibition. This was also observed but to a lesser extent for TOP2A and TOP2B. Hence, we propose the involvement of TOP3A in sensing both head-on TRCs (HO-TRCs) and co-directional TRCs (CD-TRCs). In which case, the TOP3A signals appear concentrated within the promoters and first 20 kb regions of the 5' -end of genes, suggesting the prevalence of TRCs and the recruitment of TOP3A in the 5'-regions of transcribed and replicated genes.
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Affiliation(s)
- Hongliang Zhang
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Yilun Sun
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Sourav Saha
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Liton Kumar Saha
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Lorinc S Pongor
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Anjali Dhall
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Yves Pommier
- Laboratory of Molecular Pharmacology and Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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2
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Aguirre S, Pappa S, Serna-Pujol N, Padilla N, Iacobucci S, Nacht AS, Vicent GP, Jordan A, de la Cruz X, Martínez-Balbás MA. PHF2-mediated H3K9me balance orchestrates heterochromatin stability and neural progenitor proliferation. EMBO Rep 2024:10.1038/s44319-024-00178-7. [PMID: 38890452 DOI: 10.1038/s44319-024-00178-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 05/18/2024] [Accepted: 06/04/2024] [Indexed: 06/20/2024] Open
Abstract
Heterochromatin stability is crucial for progenitor proliferation during early neurogenesis. It relays on the maintenance of local hubs of H3K9me. However, understanding the formation of efficient localized levels of H3K9me remains limited. To address this question, we used neural stem cells to analyze the function of the H3K9me2 demethylase PHF2, which is crucial for progenitor proliferation. Through mass-spectroscopy and genome-wide assays, we show that PHF2 interacts with heterochromatin components and is enriched at pericentromeric heterochromatin (PcH) boundaries where it maintains transcriptional activity. This binding is essential for silencing the satellite repeats, preventing DNA damage and genome instability. PHF2's depletion increases the transcription of heterochromatic repeats, accompanied by a decrease in H3K9me3 levels and alterations in PcH organization. We further show that PHF2's PHD and catalytic domains are crucial for maintaining PcH stability, thereby safeguarding genome integrity. These results highlight the multifaceted nature of PHF2's functions in maintaining heterochromatin stability and regulating gene expression during neural development. Our study unravels the intricate relationship between heterochromatin stability and progenitor proliferation during mammalian neurogenesis.
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Affiliation(s)
- Samuel Aguirre
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Stella Pappa
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Núria Serna-Pujol
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Natalia Padilla
- Vall d'Hebron Institute of Research (VHIR), Passeig de la Vall d'Hebron, 119, E-08035, Barcelona, Spain
| | - Simona Iacobucci
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - A Silvina Nacht
- Center for Genomic Regulation (CRG), Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Guillermo P Vicent
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Albert Jordan
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Xavier de la Cruz
- Vall d'Hebron Institute of Research (VHIR), Passeig de la Vall d'Hebron, 119, E-08035, Barcelona, Spain
- Institut Català per la Recerca i Estudis Avançats (ICREA), Barcelona, 08018, Spain
| | - Marian A Martínez-Balbás
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain.
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3
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Goehring L, Keegan S, Lahiri S, Xia W, Kong M, Jimenez-Sainz J, Gupta D, Drapkin R, Jensen RB, Smith DJ, Rothenberg E, Fenyö D, Huang TT. Dormant origin firing promotes head-on transcription-replication conflicts at transcription termination sites in response to BRCA2 deficiency. Nat Commun 2024; 15:4716. [PMID: 38830843 PMCID: PMC11148086 DOI: 10.1038/s41467-024-48286-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 04/24/2024] [Indexed: 06/05/2024] Open
Abstract
BRCA2 is a tumor suppressor protein responsible for safeguarding the cellular genome from replication stress and genotoxicity, but the specific mechanism(s) by which this is achieved to prevent early oncogenesis remains unclear. Here, we provide evidence that BRCA2 acts as a critical suppressor of head-on transcription-replication conflicts (HO-TRCs). Using Okazaki-fragment sequencing (Ok-seq) and computational analysis, we identified origins (dormant origins) that are activated near the transcription termination sites (TTS) of highly expressed, long genes in response to replication stress. Dormant origins are a source for HO-TRCs, and drug treatments that inhibit dormant origin firing led to a reduction in HO-TRCs, R-loop formation, and DNA damage. Using super-resolution microscopy, we showed that HO-TRC events track with elongating RNA polymerase II, but not with transcription initiation. Importantly, RNase H2 is recruited to sites of HO-TRCs in a BRCA2-dependent manner to help alleviate toxic R-loops associated with HO-TRCs. Collectively, our results provide a mechanistic basis for how BRCA2 shields against genomic instability by preventing HO-TRCs through both direct and indirect means occurring at predetermined genomic sites based on the pre-cancer transcriptome.
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Affiliation(s)
- Liana Goehring
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Sarah Keegan
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Institute for Systems Genetics, New York University School of Medicine, New York University School of Medicine, New York, NY, USA
| | - Sudipta Lahiri
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Wenxin Xia
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Michael Kong
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | | | - Dipika Gupta
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Ronny Drapkin
- Penn Ovarian Cancer Research Center, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
- Basser Center for BRCA, Abramson Cancer Center, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA
| | - Eli Rothenberg
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - David Fenyö
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
- Institute for Systems Genetics, New York University School of Medicine, New York University School of Medicine, New York, NY, USA
| | - Tony T Huang
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
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4
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Schreuder A, Wendel TJ, Dorresteijn CGV, Noordermeer SM. (Single-stranded DNA) gaps in understanding BRCAness. Trends Genet 2024:S0168-9525(24)00100-8. [PMID: 38789375 DOI: 10.1016/j.tig.2024.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024]
Abstract
The tumour-suppressive roles of BRCA1 and 2 have been attributed to three seemingly distinct functions - homologous recombination, replication fork protection, and single-stranded (ss)DNA gap suppression - and their relative importance is under debate. In this review, we examine the origin and resolution of ssDNA gaps and discuss the recent advances in understanding the role of BRCA1/2 in gap suppression. There are ample data showing that gap accumulation in BRCA1/2-deficient cells is linked to genomic instability and chemosensitivity. However, it remains unclear whether there is a causative role and the function of BRCA1/2 in gap suppression cannot unambiguously be dissected from their other functions. We therefore conclude that the three functions of BRCA1 and 2 are closely intertwined and not mutually exclusive.
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Affiliation(s)
- Anne Schreuder
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Tiemen J Wendel
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands
| | - Carlo G V Dorresteijn
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands
| | - Sylvie M Noordermeer
- Leiden University Medical Center, Department of Human Genetics, Leiden, The Netherlands; Oncode Institute, Utrecht, The Netherlands.
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5
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Atre M, Joshi B, Babu J, Sawant S, Sharma S, Sankar TS. Origin, evolution, and maintenance of gene-strand bias in bacteria. Nucleic Acids Res 2024; 52:3493-3509. [PMID: 38442257 DOI: 10.1093/nar/gkae155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 02/06/2024] [Accepted: 02/19/2024] [Indexed: 03/07/2024] Open
Abstract
Gene-strand bias is a characteristic feature of bacterial genome organization wherein genes are preferentially encoded on the leading strand of replication, promoting co-orientation of replication and transcription. This co-orientation bias has evolved to protect gene essentiality, expression, and genomic stability from the harmful effects of head-on replication-transcription collisions. However, the origin, variation, and maintenance of gene-strand bias remain elusive. Here, we reveal that the frequency of inversions that alter gene orientation exhibits large variation across bacterial populations and negatively correlates with gene-strand bias. The density, distance, and distribution of inverted repeats show a similar negative relationship with gene-strand bias explaining the heterogeneity in inversions. Importantly, these observations are broadly evident across the entire bacterial kingdom uncovering inversions and inverted repeats as primary factors underlying the variation in gene-strand bias and its maintenance. The distinct catalytic subunits of replicative DNA polymerase have co-evolved with gene-strand bias, suggesting a close link between replication and the origin of gene-strand bias. Congruently, inversion frequencies and inverted repeats vary among bacteria with different DNA polymerases. In summary, we propose that the nature of replication determines the fitness cost of replication-transcription collisions, establishing a selection gradient on gene-strand bias by fine-tuning DNA sequence repeats and, thereby, gene inversions.
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Affiliation(s)
- Malhar Atre
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Bharat Joshi
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Jebin Babu
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Shabduli Sawant
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Shreya Sharma
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - T Sabari Sankar
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
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6
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Rombaut D, Lefèvre C, Rached T, Bondu S, Letessier A, Mangione RM, Farhat B, Lesieur-Pasquier A, Castillo-Guzman D, Boussaid I, Friedrich C, Tourville A, De Carvalho M, Levavasseur F, Leduc M, Le Gall M, Battault S, Temple M, Houy A, Bouscary D, Willems L, Park S, Raynaud S, Cluzeau T, Clappier E, Fenaux P, Adès L, Margueron R, Wassef M, Alsafadi S, Chapuis N, Kosmider O, Solary E, Constantinou A, Stern MH, Droin N, Palancade B, Miotto B, Chédin F, Fontenay M. Accelerated DNA replication fork speed due to loss of R-loops in myelodysplastic syndromes with SF3B1 mutation. Nat Commun 2024; 15:3016. [PMID: 38589367 PMCID: PMC11001894 DOI: 10.1038/s41467-024-46547-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/29/2024] [Indexed: 04/10/2024] Open
Abstract
Myelodysplastic syndromes (MDS) with mutated SF3B1 gene present features including a favourable outcome distinct from MDS with mutations in other splicing factor genes SRSF2 or U2AF1. Molecular bases of these divergences are poorly understood. Here we find that SF3B1-mutated MDS show reduced R-loop formation predominating in gene bodies associated with intron retention reduction, not found in U2AF1- or SRSF2-mutated MDS. Compared to erythroblasts from SRSF2- or U2AF1-mutated patients, SF3B1-mutated erythroblasts exhibit augmented DNA synthesis, accelerated replication forks, and single-stranded DNA exposure upon differentiation. Importantly, histone deacetylase inhibition using vorinostat restores R-loop formation, slows down DNA replication forks and improves SF3B1-mutated erythroblast differentiation. In conclusion, loss of R-loops with associated DNA replication stress represents a hallmark of SF3B1-mutated MDS ineffective erythropoiesis, which could be used as a therapeutic target.
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Affiliation(s)
- David Rombaut
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
- Laboratoire d'excellence du Globule Rouge GR-Ex, Université Paris Cité, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Carine Lefèvre
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
- Laboratoire d'excellence du Globule Rouge GR-Ex, Université Paris Cité, Paris, France
| | - Tony Rached
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Sabrina Bondu
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Anne Letessier
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
| | | | - Batoul Farhat
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Auriane Lesieur-Pasquier
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Daisy Castillo-Guzman
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA, USA
| | - Ismael Boussaid
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Chloé Friedrich
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Aurore Tourville
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Magali De Carvalho
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Françoise Levavasseur
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Marjorie Leduc
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Platform Proteom'IC, Université Paris Cité, Institut Cochin, Paris, France
| | - Morgane Le Gall
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Platform Proteom'IC, Université Paris Cité, Institut Cochin, Paris, France
| | - Sarah Battault
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
| | - Marie Temple
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Alexandre Houy
- Institut Curie, PSL Research University, Sorbonne University, INSERM U830, DNA repair and uveal melanoma, Equipe labellisée par la Ligue Nationale contre le Cancer, Paris, France
| | - Didier Bouscary
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Clinical Department of Hematology, Paris, France
| | - Lise Willems
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Clinical Department of Hematology, Paris, France
| | - Sophie Park
- Department of Hematology, Centre Hospitalier Universitaire, Université de Grenoble Alpes, Grenoble, France
| | - Sophie Raynaud
- Laboratory of Hematology, Université Côte d'Azur, Centre Hospitalier Universitaire, Nice, France
| | - Thomas Cluzeau
- Clinical Department of Hematology, Université Côte d'Azur, Centre Hospitalier Universitaire, Nice, France
| | - Emmanuelle Clappier
- Assistance Publique-Hôpitaux de Paris.Nord-Université Paris Cité, Saint-Louis Hospital, Laboratory of Hematology, Paris, France
| | - Pierre Fenaux
- Assistance Publique-Hôpitaux de Paris.Nord-Université Paris Cité, Saint-Louis Hospital, Service Hématologie Séniors, Paris, France
| | - Lionel Adès
- Assistance Publique-Hôpitaux de Paris.Nord-Université Paris Cité, Saint-Louis Hospital, Service Hématologie Séniors, Paris, France
| | - Raphael Margueron
- Institut Curie, Paris Sciences Lettres Research University, Sorbonne University, INSERM U934, UMR3215, Paris, France
| | - Michel Wassef
- Institut Curie, Paris Sciences Lettres Research University, Sorbonne University, INSERM U934, UMR3215, Paris, France
| | - Samar Alsafadi
- Institut Curie, PSL Research University, Sorbonne University, INSERM U830, DNA repair and uveal melanoma, Equipe labellisée par la Ligue Nationale contre le Cancer, Paris, France
| | - Nicolas Chapuis
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Olivier Kosmider
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France
| | - Eric Solary
- Institut Gustave Roussy, INSERM 1287, Université Paris Saclay, Villejuif, France
| | - Angelos Constantinou
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, Université de Montpellier, Montpellier, France
| | - Marc-Henri Stern
- Institut Curie, PSL Research University, Sorbonne University, INSERM U830, DNA repair and uveal melanoma, Equipe labellisée par la Ligue Nationale contre le Cancer, Paris, France
| | - Nathalie Droin
- Institut Gustave Roussy, INSERM 1287, Université Paris Saclay, Villejuif, France
| | - Benoit Palancade
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Benoit Miotto
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA, USA
| | - Michaela Fontenay
- Université Paris Cité, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Cochin, Paris, France.
- Equipe labellisée par la Fondation pour la Recherche Médicale, Paris, France.
- Laboratoire d'excellence du Globule Rouge GR-Ex, Université Paris Cité, Paris, France.
- Assistance Publique-Hôpitaux de Paris.Centre-Université Paris Cité, Hôpital Cochin, Laboratory of Hematology, Paris, France.
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7
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Fang Y, Li X. Protein lysine four-carbon acylations in health and disease. J Cell Physiol 2024; 239:e30981. [PMID: 36815448 PMCID: PMC10704440 DOI: 10.1002/jcp.30981] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/03/2023] [Accepted: 02/09/2023] [Indexed: 02/24/2023]
Abstract
Lysine acylation, a type of posttranslational protein modification sensitive to cellular metabolic states, influences the functions of target proteins involved in diverse cellular processes. Particularly, lysine butyrylation, crotonylation, β-hydroxybutyrylation, and 2-hydroxyisobutyrylation, four types of four-carbon acylations, are modulated by intracellular concentrations of their respective acyl-CoAs and sensitive to alterations of nutrient metabolism induced by cellular and/or environmental signals. In this review, we discussed the metabolic pathways producing these four-carbon acyl-CoAs, the regulation of lysine acylation and deacylation, and the functions of individual lysine acylation.
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Affiliation(s)
- Yi Fang
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Xiaoling Li
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
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8
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Wollman AJM, Syeda AH, Howard JAL, Payne-Dwyer A, Leech A, Warecka D, Guy C, McGlynn P, Hawkins M, Leake MC. Tetrameric UvrD Helicase Is Located at the E. Coli Replisome due to Frequent Replication Blocks. J Mol Biol 2024; 436:168369. [PMID: 37977299 DOI: 10.1016/j.jmb.2023.168369] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 11/10/2023] [Accepted: 11/11/2023] [Indexed: 11/19/2023]
Abstract
DNA replication in all organisms must overcome nucleoprotein blocks to complete genome duplication. Accessory replicative helicases in Escherichia coli, Rep and UvrD, help remove these blocks and aid the re-initiation of replication. Mechanistic details of Rep function have emerged from recent live cell studies; however, the division of UvrD functions between its activities in DNA repair and role as an accessory helicase remain unclear in live cells. By integrating super-resolved single-molecule fluorescence microscopy with biochemical analysis, we find that UvrD self-associates into tetrameric assemblies and, unlike Rep, is not recruited to a specific replisome protein despite being found at approximately 80% of replication forks. Instead, its colocation with forks is likely due to the very high frequency of replication blocks composed of DNA-bound proteins, including RNA polymerase and factors involved in repairing DNA damage. Deleting rep and DNA repair factor genes mutS and uvrA, and inhibiting transcription through RNA polymerase mutation and antibiotic inhibition, indicates that the level of UvrD at the fork is dependent on UvrD's function. Our findings show that UvrD is recruited to sites of nucleoprotein blocks via different mechanisms to Rep and plays a multi-faceted role in ensuring successful DNA replication.
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Affiliation(s)
- Adam J M Wollman
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Aisha H Syeda
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Jamieson A L Howard
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Alex Payne-Dwyer
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Andrew Leech
- Bioscience Technology Facility, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Dominika Warecka
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Colin Guy
- Covance Laboratories Ltd., Otley Road, Harrogate HG3 1PY, United Kingdom
| | - Peter McGlynn
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Michelle Hawkins
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Mark C Leake
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom.
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9
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Carrasco B, Torres R, Moreno-del Álamo M, Ramos C, Ayora S, Alonso JC. Processing of stalled replication forks in Bacillus subtilis. FEMS Microbiol Rev 2024; 48:fuad065. [PMID: 38052445 PMCID: PMC10804225 DOI: 10.1093/femsre/fuad065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/07/2023] Open
Abstract
Accurate DNA replication and transcription elongation are crucial for preventing the accumulation of unreplicated DNA and genomic instability. Cells have evolved multiple mechanisms to deal with impaired replication fork progression, challenged by both intrinsic and extrinsic impediments. The bacterium Bacillus subtilis, which adopts multiple forms of differentiation and development, serves as an excellent model system for studying the pathways required to cope with replication stress to preserve genomic stability. This review focuses on the genetics, single molecule choreography, and biochemical properties of the proteins that act to circumvent the replicative arrest allowing the resumption of DNA synthesis. The RecA recombinase, its mediators (RecO, RecR, and RadA/Sms) and modulators (RecF, RecX, RarA, RecU, RecD2, and PcrA), repair licensing (DisA), fork remodelers (RuvAB, RecG, RecD2, RadA/Sms, and PriA), Holliday junction resolvase (RecU), nucleases (RnhC and DinG), and translesion synthesis DNA polymerases (PolY1 and PolY2) are key functions required to overcome a replication stress, provided that the fork does not collapse.
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Affiliation(s)
- Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
| | - Rubén Torres
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
| | - María Moreno-del Álamo
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
| | - Cristina Ramos
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str, 28049 Madrid, Spain
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10
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Kumar C, Remus D. Looping out of control: R-loops in transcription-replication conflict. Chromosoma 2024; 133:37-56. [PMID: 37419963 PMCID: PMC10771546 DOI: 10.1007/s00412-023-00804-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023]
Abstract
Transcription-replication conflict is a major cause of replication stress that arises when replication forks collide with the transcription machinery. Replication fork stalling at sites of transcription compromises chromosome replication fidelity and can induce DNA damage with potentially deleterious consequences for genome stability and organismal health. The block to DNA replication by the transcription machinery is complex and can involve stalled or elongating RNA polymerases, promoter-bound transcription factor complexes, or DNA topology constraints. In addition, studies over the past two decades have identified co-transcriptional R-loops as a major source for impairment of DNA replication forks at active genes. However, how R-loops impede DNA replication at the molecular level is incompletely understood. Current evidence suggests that RNA:DNA hybrids, DNA secondary structures, stalled RNA polymerases, and condensed chromatin states associated with R-loops contribute to the of fork progression. Moreover, since both R-loops and replication forks are intrinsically asymmetric structures, the outcome of R-loop-replisome collisions is influenced by collision orientation. Collectively, the data suggest that the impact of R-loops on DNA replication is highly dependent on their specific structural composition. Here, we will summarize our current understanding of the molecular basis for R-loop-induced replication fork progression defects.
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Affiliation(s)
- Charanya Kumar
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA.
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11
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Wang J, Maschietto F, Qiu T, Arantes PR, Skeens E, Palermo G, Lisi GP, Batista VS. Substrate-independent activation pathways of the CRISPR-Cas9 HNH nuclease. Biophys J 2023; 122:4635-4644. [PMID: 37936350 PMCID: PMC10754686 DOI: 10.1016/j.bpj.2023.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/29/2023] [Accepted: 11/03/2023] [Indexed: 11/09/2023] Open
Abstract
A hallmark of tightly regulated high-fidelity enzymes is that they become activated only after encountering cognate substrates, often by an induced-fit mechanism rather than conformational selection. Upon analysis of molecular dynamics trajectories, we recently discovered that the Cas9 HNH domain exists in three conformations: 1) Y836 (which is two residues away from the catalytic D839 and H840 residues) is hydrogen bonded to the D829 backbone amide, 2) Y836 is hydrogen bonded to the backbone amide of D861 (which is one residue away from the third catalytic residue N863), and 3) Y836 is not hydrogen bonded to either residue. Each of the three conformers differs from the active state of HNH. The conversion between the inactive and active states involves a local unfolding-refolding process that displaces the Cα and side chain of the catalytic N863 residue by ∼5 Å and ∼10 Å, respectively. In this study, we report the two largest principal components of coordinate variance of the HNH domain throughout molecular dynamics trajectories to establish the interconversion pathways of these conformations. We show that conformation 2 is an obligate step between conformations 1 and 3, which are not directly interconvertible without conformation 2. The loss of hydrogen bonding of the Y836 side chain in conformation 3 likely plays an essential role in activation during local unfolding-refolding of an α-helix containing the catalytic N863. Three single Lys-to-Ala mutants appear to eliminate this substrate-independent activation pathway of the wild-type HNH nuclease, thereby enhancing the fidelity of HNH cleavage.
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Affiliation(s)
- Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.
| | | | - Tianyin Qiu
- Department of Chemistry, Yale University, New Haven, Connecticut
| | - Pablo R Arantes
- Department of Bioengineering, University of California, Riverside, Riverside, California
| | - Erin Skeens
- Department of Chemistry, University of California, Riverside, Riverside, California
| | - Giulia Palermo
- Department of Bioengineering, University of California, Riverside, Riverside, California; Department of Chemistry, University of California, Riverside, Riverside, California.
| | - George P Lisi
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island.
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, Connecticut.
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12
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Anda M, Yamanouchi S, Cosentino S, Sakamoto M, Ohkuma M, Takashima M, Toyoda A, Iwasaki W. Bacteria can maintain rRNA operons solely on plasmids for hundreds of millions of years. Nat Commun 2023; 14:7232. [PMID: 37963895 PMCID: PMC10645730 DOI: 10.1038/s41467-023-42681-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 10/17/2023] [Indexed: 11/16/2023] Open
Abstract
It is generally assumed that all bacteria must have at least one rRNA operon (rrn operon) on the chromosome, but some strains of the genera Aureimonas and Oecophyllibacter carry their sole rrn operon on a plasmid. However, other related strains and species have chromosomal rrn loci, suggesting that the exclusive presence of rrn operons on a plasmid is rare and unlikely to be stably maintained over long evolutionary periods. Here, we report the results of a systematic search for additional bacteria without chromosomal rrn operons. We find that at least four bacterial clades in the phyla Bacteroidota, Spirochaetota, and Pseudomonadota (Proteobacteria) lost chromosomal rrn operons independently. Remarkably, Persicobacteraceae have apparently maintained this peculiar genome organization for hundreds of millions of years. In our study, all the rrn-carrying plasmids in bacteria lacking chromosomal rrn loci possess replication initiator genes of the Rep_3 family. Furthermore, the lack of chromosomal rrn operons is associated with differences in copy numbers of rrn operons, plasmids, and chromosomal tRNA genes. Thus, our findings indicate that the absence of rrn loci in bacterial chromosomes can be stably maintained over long evolutionary periods.
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Affiliation(s)
- Mizue Anda
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba, 277-0882, Japan.
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - Shun Yamanouchi
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Salvatore Cosentino
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba, 277-0882, Japan
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Mitsuo Sakamoto
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Moriya Ohkuma
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Masako Takashima
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Atsushi Toyoda
- Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Wataru Iwasaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba, 277-0882, Japan.
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba, 277-0882, Japan.
- Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba, 277-0882, Japan.
- Institute for Quantitative Biosciences, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
- Collaborative Research Institute for Innovative Microbiology, the University of Tokyo, Bunkyo-ku, Tokyo, 113-0032, Japan.
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13
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Ji P, Zhang G, Guo Y, Song H, Yuan X, Hu X, Guo Z, Xia P, Shen R, Wang D. Protein crotonylation: An emerging regulator in DNA damage response. Life Sci 2023; 331:122059. [PMID: 37652154 DOI: 10.1016/j.lfs.2023.122059] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/16/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
DNA damage caused by internal or external factors lead to increased genomic instability and various diseases. The DNA damage response (DDR) is a crucial mechanism that maintaining genomic stability through detecting and repairing DNA damage timely. Post-translational modifications (PTMs) play significant roles in regulation of DDR. Among the present PTMs, crotonylation has emerged as a novel identified modification that is involved in a wide range of biological processes including gene expression, spermatogenesis, cell cycle, and the development of diverse diseases. In the past decade, numerous crotonylation sites have been identified in histone and non-histone proteins, leading to a more comprehensive and deep understanding of the function and mechanisms in protein crotonylation. This review provides a comprehensive overview of the regulatory mechanisms of protein crotonylation and the effect of crotonylation in DDR. Furthermore, the effect of protein crotonylation in tumor development and progression is presented, to inspire and explore the novel strategies for tumor therapy.
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Affiliation(s)
- Pengfei Ji
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Guokun Zhang
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Yanan Guo
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Haoyun Song
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Xinyi Yuan
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Xiaohui Hu
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Zhao Guo
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Peng Xia
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Rong Shen
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China.
| | - Degui Wang
- School of basic medical sciences, Lanzhou University, Lanzhou, Gansu Province 73000, China; NHC Key Laboratory of diagnosis and therapy of Gastrointestinal Tumor, Lanzhou, Gansu Province 730000, China.
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14
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Fan J, El Sayyed H, Pambos OJ, Stracy M, Kyropoulos J, Kapanidis AN. RNA polymerase redistribution supports growth in E. coli strains with a minimal number of rRNA operons. Nucleic Acids Res 2023; 51:8085-8101. [PMID: 37351576 PMCID: PMC10450203 DOI: 10.1093/nar/gkad511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/24/2023] [Accepted: 06/02/2023] [Indexed: 06/24/2023] Open
Abstract
Bacterial transcription by RNA polymerase (RNAP) is spatially organized. RNAPs transcribing highly expressed genes locate in the nucleoid periphery, and form clusters in rich medium, with several studies linking RNAP clustering and transcription of rRNA (rrn). However, the nature of RNAP clusters and their association with rrn transcription remains unclear. Here we address these questions by using single-molecule tracking to monitor the subcellular distribution of mobile and immobile RNAP in strains with a heavily reduced number of chromosomal rrn operons (Δrrn strains). Strikingly, we find that the fraction of chromosome-associated RNAP (which is mainly engaged in transcription) is robust to deleting five or six of the seven chromosomal rrn operons. Spatial analysis in Δrrn strains showed substantial RNAP redistribution during moderate growth, with clustering increasing at cell endcaps, where the remaining rrn operons reside. These results support a model where RNAPs in Δrrn strains relocate to copies of the remaining rrn operons. In rich medium, Δrrn strains redistribute RNAP to minimize growth defects due to rrn deletions, with very high RNAP densities on rrn genes leading to genomic instability. Our study links RNAP clusters and rrn transcription, and offers insight into how bacteria maintain growth in the presence of only 1-2 rrn operons.
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Affiliation(s)
- Jun Fan
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731, China
| | - Hafez El Sayyed
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin building, University of Oxford, Sherrington Road, Oxford OX1 3QU, UK
| | - Oliver J Pambos
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin building, University of Oxford, Sherrington Road, Oxford OX1 3QU, UK
| | - Mathew Stracy
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Jingwen Kyropoulos
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin building, University of Oxford, Sherrington Road, Oxford OX1 3QU, UK
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15
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Dinatto L, Stirling PC. Go along to get along: Integrator at active replication forks defuses co-directional transcription-replication conflicts. Mol Cell 2023; 83:2161-2163. [PMID: 37419089 DOI: 10.1016/j.molcel.2023.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/05/2023] [Accepted: 06/05/2023] [Indexed: 07/09/2023]
Abstract
There has been growing appreciation that transcription is an endogenous source of replication stress and must be coordinated with replication. In this issue, Bhowmick et al.1 uncover a protective mechanism that prevents co-directional transcription-replication conflicts (TRCs) from becoming genotoxic.
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Affiliation(s)
- Leticia Dinatto
- Terry Fox Laboratory, British Columbia Cancer Research Institute, Vancouver, BC, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Peter C Stirling
- Terry Fox Laboratory, British Columbia Cancer Research Institute, Vancouver, BC, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
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16
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Blaine HC, Simmons LA, Stallings CL. Diverse Mechanisms of Helicase Loading during DNA Replication Initiation in Bacteria. J Bacteriol 2023; 205:e0048722. [PMID: 36877032 PMCID: PMC10128896 DOI: 10.1128/jb.00487-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023] Open
Abstract
Initiation of DNA replication is required for cell viability and passage of genetic information to the next generation. Studies in Escherichia coli and Bacillus subtilis have established ATPases associated with diverse cellular activities (AAA+) as essential proteins required for loading of the replicative helicase at replication origins. AAA+ ATPases DnaC in E. coli and DnaI in B. subtilis have long been considered the paradigm for helicase loading during replication in bacteria. Recently, it has become increasingly clear that most bacteria lack DnaC/DnaI homologs. Instead, most bacteria express a protein homologous to the newly described DciA (dnaC/dnaI antecedent) protein. DciA is not an ATPase, and yet it serves as a helicase operator, providing a function analogous to that of DnaC and DnaI across diverse bacterial species. The recent discovery of DciA and of other alternative mechanisms of helicase loading in bacteria has changed our understanding of DNA replication initiation. In this review, we highlight recent discoveries, detailing what is currently known about the replicative helicase loading process across bacterial species, and we discuss the critical questions that remain to be investigated.
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Affiliation(s)
- Helen C. Blaine
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Lyle A. Simmons
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Christina L. Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, Saint Louis, Missouri, USA
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17
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Huang D, Johnson AE, Sim BS, Lo TW, Merrikh H, Wiggins PA. The in vivo measurement of replication fork velocity and pausing by lag-time analysis. Nat Commun 2023; 14:1762. [PMID: 36997519 PMCID: PMC10063678 DOI: 10.1038/s41467-023-37456-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 03/17/2023] [Indexed: 03/31/2023] Open
Abstract
AbstractAn important step towards understanding the mechanistic basis of the central dogma is the quantitative characterization of the dynamics of nucleic-acid-bound molecular motors in the context of the living cell. To capture these dynamics, we develop lag-time analysis, a method for measuring in vivo dynamics. Using this approach, we provide quantitative locus-specific measurements of fork velocity, in units of kilobases per second, as well as replisome pause durations, some with the precision of seconds. The measured fork velocity is observed to be both locus and time dependent, even in wild-type cells. In this work, we quantitatively characterize known phenomena, detect brief, locus-specific pauses at ribosomal DNA loci in wild-type cells, and observe temporal fork velocity oscillations in three highly-divergent bacterial species.
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18
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Stoy H, Zwicky K, Kuster D, Lang KS, Krietsch J, Crossley MP, Schmid JA, Cimprich KA, Merrikh H, Lopes M. Direct visualization of transcription-replication conflicts reveals post-replicative DNA:RNA hybrids. Nat Struct Mol Biol 2023; 30:348-359. [PMID: 36864174 PMCID: PMC10023573 DOI: 10.1038/s41594-023-00928-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 01/23/2023] [Indexed: 03/04/2023]
Abstract
Transcription-replication collisions (TRCs) are crucial determinants of genome instability. R-loops were linked to head-on TRCs and proposed to obstruct replication fork progression. The underlying mechanisms, however, remained elusive due to the lack of direct visualization and of non-ambiguous research tools. Here, we ascertained the stability of estrogen-induced R-loops on the human genome, visualized them directly by electron microscopy (EM), and measured R-loop frequency and size at the single-molecule level. Combining EM and immuno-labeling on locus-specific head-on TRCs in bacteria, we observed the frequent accumulation of DNA:RNA hybrids behind replication forks. These post-replicative structures are linked to fork slowing and reversal across conflict regions and are distinct from physiological DNA:RNA hybrids at Okazaki fragments. Comet assays on nascent DNA revealed a marked delay in nascent DNA maturation in multiple conditions previously linked to R-loop accumulation. Altogether, our findings suggest that TRC-associated replication interference entails transactions that follow initial R-loop bypass by the replication fork.
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Affiliation(s)
- Henriette Stoy
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Katharina Zwicky
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Danina Kuster
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Kevin S Lang
- Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN, USA
| | - Jana Krietsch
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Magdalena P Crossley
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jonas A Schmid
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Houra Merrikh
- Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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19
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Li X, Wang L, Liu X, Zheng Z, Kong D. Cellular regulation and stability of DNA replication forks in eukaryotic cells. DNA Repair (Amst) 2022; 120:103418. [DOI: 10.1016/j.dnarep.2022.103418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/03/2022] [Accepted: 10/07/2022] [Indexed: 11/03/2022]
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20
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Lee H, You SY, Han DW, La H, Park C, Yoo S, Kang K, Kang MH, Choi Y, Hong K. Dynamic Change of R-Loop Implicates in the Regulation of Zygotic Genome Activation in Mouse. Int J Mol Sci 2022; 23:ijms232214345. [PMID: 36430821 PMCID: PMC9699122 DOI: 10.3390/ijms232214345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 11/22/2022] Open
Abstract
In mice, zygotic genome activation (ZGA) occurs in two steps: minor ZGA at the one-cell stage and major ZGA at the two-cell stage. Regarding the regulation of gene transcription, minor ZGA is known to have unique features, including a transcriptionally permissive state of chromatin and insufficient splicing processes. The molecular characteristics may originate from extremely open chromatin states in the one-cell stage zygotes, yet the precise underlying mechanism has not been well studied. Recently, the R-loop, a triple-stranded nucleic acid structure of the DNA/RNA hybrid, has been implicated in gene transcription and DNA replication. Therefore, in the present study, we examined the changes in R-loop dynamics during mouse zygotic development, and its roles in zygotic transcription or DNA replication. Our analysis revealed that R-loops persist in the genome of metaphase II oocytes and preimplantation embryos from the zygote to the blastocyst stage. In particular, zygotic R-loop levels dynamically change as development proceeds, showing that R-loop levels decrease as pronucleus maturation occurs. Mechanistically, R-loop dynamics are likely linked to ZGA, as inhibition of either DNA replication or transcription at the time of minor ZGA decreases R-loop levels in the pronuclei of zygotes. However, the induction of DNA damage by treatment with anticancer agents, including cisplatin or doxorubicin, does not elicit genome-wide changes in zygotic R-loop levels. Therefore, our study suggests that R-loop formation is mechanistically associated with the regulation of mouse ZGA, especially minor ZGA, by modulating gene transcription and DNA replication.
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Affiliation(s)
- Hyeonji Lee
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Seong-Yeob You
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Dong Wook Han
- Guangdong Provincial Key Laboratory of Large Animal Models for Biomedicine, Wuyi University, Jiangmen 529020, China
| | - Hyeonwoo La
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Chanhyeok Park
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Seonho Yoo
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Kiye Kang
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Min-Hee Kang
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Youngsok Choi
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
| | - Kwonho Hong
- Department of Stem Cell and Regenerative Biotechnology, Institute of Advanced Regenerative Science, Konkuk University, Seoul 05029, Republic of Korea
- Correspondence:
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21
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Mirceta M, Shum N, Schmidt MHM, Pearson CE. Fragile sites, chromosomal lesions, tandem repeats, and disease. Front Genet 2022; 13:985975. [PMID: 36468036 PMCID: PMC9714581 DOI: 10.3389/fgene.2022.985975] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/02/2022] [Indexed: 09/16/2023] Open
Abstract
Expanded tandem repeat DNAs are associated with various unusual chromosomal lesions, despiralizations, multi-branched inter-chromosomal associations, and fragile sites. Fragile sites cytogenetically manifest as localized gaps or discontinuities in chromosome structure and are an important genetic, biological, and health-related phenomena. Common fragile sites (∼230), present in most individuals, are induced by aphidicolin and can be associated with cancer; of the 27 molecularly-mapped common sites, none are associated with a particular DNA sequence motif. Rare fragile sites ( ≳ 40 known), ≤ 5% of the population (may be as few as a single individual), can be associated with neurodevelopmental disease. All 10 molecularly-mapped folate-sensitive fragile sites, the largest category of rare fragile sites, are caused by gene-specific CGG/CCG tandem repeat expansions that are aberrantly CpG methylated and include FRAXA, FRAXE, FRAXF, FRA2A, FRA7A, FRA10A, FRA11A, FRA11B, FRA12A, and FRA16A. The minisatellite-associated rare fragile sites, FRA10B, FRA16B, can be induced by AT-rich DNA-ligands or nucleotide analogs. Despiralized lesions and multi-branched inter-chromosomal associations at the heterochromatic satellite repeats of chromosomes 1, 9, 16 are inducible by de-methylating agents like 5-azadeoxycytidine and can spontaneously arise in patients with ICF syndrome (Immunodeficiency Centromeric instability and Facial anomalies) with mutations in genes regulating DNA methylation. ICF individuals have hypomethylated satellites I-III, alpha-satellites, and subtelomeric repeats. Ribosomal repeats and subtelomeric D4Z4 megasatellites/macrosatellites, are associated with chromosome location, fragility, and disease. Telomere repeats can also assume fragile sites. Dietary deficiencies of folate or vitamin B12, or drug insults are associated with megaloblastic and/or pernicious anemia, that display chromosomes with fragile sites. The recent discovery of many new tandem repeat expansion loci, with varied repeat motifs, where motif lengths can range from mono-nucleotides to megabase units, could be the molecular cause of new fragile sites, or other chromosomal lesions. This review focuses on repeat-associated fragility, covering their induction, cytogenetics, epigenetics, cell type specificity, genetic instability (repeat instability, micronuclei, deletions/rearrangements, and sister chromatid exchange), unusual heritability, disease association, and penetrance. Understanding tandem repeat-associated chromosomal fragile sites provides insight to chromosome structure, genome packaging, genetic instability, and disease.
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Affiliation(s)
- Mila Mirceta
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Natalie Shum
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Monika H. M. Schmidt
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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22
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McLean EK, Nye TM, Lowder FC, Simmons LA. The Impact of RNA-DNA Hybrids on Genome Integrity in Bacteria. Annu Rev Microbiol 2022; 76:461-480. [PMID: 35655343 PMCID: PMC9527769 DOI: 10.1146/annurev-micro-102521-014450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
During the essential processes of DNA replication and transcription, RNA-DNA hybrid intermediates are formed that pose significant risks to genome integrity when left unresolved. To manage RNA-DNA hybrids, all cells rely on RNase H family enzymes that specifically cleave the RNA portion of the many different types of hybrids that form in vivo. Recent experimental advances have provided new insight into how RNA-DNA hybrids form and the consequences to genome integrity that ensue when persistent hybrids remain unresolved. Here we review the types of RNA-DNA hybrids, including R-loops, RNA primers, and ribonucleotide misincorporations, that form during DNA replication and transcription and discuss how each type of hybrid can contribute to genome instability in bacteria. Further, we discuss how bacterial RNase HI, HII, and HIII and bacterial FEN enzymes contribute to genome maintenance through the resolution of hybrids.
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Affiliation(s)
- Emma K McLean
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
| | - Taylor M Nye
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
- Current affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Frances C Lowder
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
| | - Lyle A Simmons
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA;
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23
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Hao S, Wang Y, Zhao Y, Gao W, Cui W, Li Y, Cui J, Liu Y, Lin L, Xu X, Wang H. Dynamic switching of crotonylation to ubiquitination of H2A at lysine 119 attenuates transcription-replication conflicts caused by replication stress. Nucleic Acids Res 2022; 50:9873-9892. [PMID: 36062559 PMCID: PMC9508856 DOI: 10.1093/nar/gkac734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/20/2022] [Accepted: 08/18/2022] [Indexed: 11/21/2022] Open
Abstract
The reversible post-translational modification (PTM) of proteins plays an important role in many cellular processes. Lysine crotonylation (Kcr) is a newly identified PTM, but its functional significance remains unclear. Here, we found that Kcr is involved in the replication stress response. We show that crotonylation of histone H2A at lysine 119 (H2AK119) and ubiquitination of H2AK119 are reversibly regulated by replication stress. Decrotonylation of H2AK119 by SIRT1 is a prerequisite for subsequent ubiquitination of H2AK119 by BMI1. Accumulation of ubiquitinated H2AK119 at reversed replication forks leads to the release of RNA Polymerase II and transcription repression in the vicinity of stalled replication forks. These effects attenuate transcription–replication conflicts (TRCs) and TRC-associated R-loop formation and DNA double-strand breaks. These findings suggest that decrotonylation and ubiquitination of H2A at lysine 119 act together to resolve replication stress-induced TRCs and protect genome stability.
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Affiliation(s)
- Shuailin Hao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ya Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yuqin Zhao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Wen Gao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Wei Cui
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Youhang Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jian Cui
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yu Liu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Lixiu Lin
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xingzhi Xu
- Guangdong Key Laboratory for Genome Stability and Disease Prevention and Carson International Cancer Center, Marshall Laboratory of Biomedical Engineering, China Shenzhen University School of Medicine, Shenzhen, Guangdong 518060, China
| | - Hailong Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
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24
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Miropolskaya N, Petushkov I, Esyunina D, Kulbachinskiy A. Suppressor mutations in Escherichia coli RNA polymerase alter transcription initiation but do not affect translesion RNA synthesis in vitro. J Biol Chem 2022; 298:102099. [PMID: 35667439 PMCID: PMC9254596 DOI: 10.1016/j.jbc.2022.102099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/19/2022] Open
Abstract
Bacterial RNA polymerase (RNAP) coordinates transcription with DNA repair and replication. Many RNAP mutations have pleiotropic phenotypes with profound effects on transcription-coupled processes. One class of RNAP mutations (rpo*) has been shown to suppress mutations in regulatory factors responsible for changes in gene expression during stationary phase or starvation, as well as in factors involved in the restoration of replication forks after DNA damage. These mutations were suggested to affect the ability of RNAP to transcribe damaged DNA and to decrease the stability of transcription complexes, thus facilitating their dislodging during DNA replication and repair, although this was not explicitly demonstrated. Here, we obtained nine mutations of this class located around the DNA/RNA binding cleft of E. coli RNAP and analyzed their transcription properties in vitro. We found that these mutations decreased promoter complex stability to varying degrees and all decreased the activity of rRNA promoters. However, they did not have strong effects on elongation complex stability. Some mutations were shown to stimulate transcriptional pauses or decrease intrinsic RNA cleavage by RNAP, but none altered the ability of RNAP to transcribe DNA templates containing damaged nucleotides. Thus, we conclude that the suppressor phenotypes of the mutations are unlikely to result from direct effects on DNA lesion recognition by RNAP but may be primarily explained by changes in transcription initiation. Further analysis of the effects of these mutations on the genomic distribution of RNAP and its interactions with regulatory factors will be essential for understanding their diverse phenotypes in vivo.
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Affiliation(s)
- Nataliya Miropolskaya
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia
| | - Ivan Petushkov
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia
| | - Daria Esyunina
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia.
| | - Andrey Kulbachinskiy
- Institute of Molecular Genetics, National Research Center "Kurchatov Institute", Moscow, Russia.
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25
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Fleurier S, Dapa T, Tenaillon O, Condon C, Matic I. rRNA operon multiplicity as a bacterial genome stability insurance policy. Nucleic Acids Res 2022; 50:12601-12620. [PMID: 35552441 PMCID: PMC9825170 DOI: 10.1093/nar/gkac332] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 04/12/2022] [Accepted: 04/21/2022] [Indexed: 01/29/2023] Open
Abstract
Quick growth restart after upon encountering favourable environmental conditions is a major fitness contributor in natural environment. It is widely assumed that the time required to restart growth after nutritional upshift is determined by how long it takes for cells to synthesize enough ribosomes to produce the proteins required to reinitiate growth. Here we show that a reduction in the capacity to synthesize ribosomes by reducing number of ribosomal RNA (rRNA) operons (rrn) causes a longer transition from stationary phase to growth of Escherichia coli primarily due to high mortality rates. Cell death results from DNA replication blockage and massive DNA breakage at the sites of the remaining rrn operons that become overloaded with RNA polymerases (RNAPs). Mortality rates and growth restart duration can be reduced by preventing R-loop formation and improving DNA repair capacity. The same molecular mechanisms determine the duration of the recovery phase after ribosome-damaging stresses, such as antibiotics, exposure to bile salts or high temperature. Our study therefore suggests that a major function of rrn operon multiplicity is to ensure that individual rrn operons are not saturated by RNAPs, which can result in catastrophic chromosome replication failure and cell death during adaptation to environmental fluctuations.
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Affiliation(s)
- Sebastien Fleurier
- Department of Infection, Immunity and Inflammation, Institut Cochin, Inserm U1016, CNRS UMR8104, Université de Paris, 75014 Paris, France
| | - Tanja Dapa
- Department of Infection, Immunity and Inflammation, Institut Cochin, Inserm U1016, CNRS UMR8104, Université de Paris, 75014 Paris, France
| | | | - Ciarán Condon
- Institut de Biologie Physico-Chimique, CNRS UMR8261, Université de Paris, 75005 Paris, France
| | - Ivan Matic
- To whom correspondence should be addressed.
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26
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Break-induced replication: unraveling each step. Trends Genet 2022; 38:752-765. [PMID: 35459559 DOI: 10.1016/j.tig.2022.03.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 10/18/2022]
Abstract
Break-induced replication (BIR) repairs one-ended double-strand DNA breaks through invasion into a homologous template followed by DNA synthesis. Different from S-phase replication, BIR copies the template DNA in a migrating displacement loop (D-loop) and results in conservative inheritance of newly synthesized DNA. This unusual mode of DNA synthesis makes BIR a source of various genetic instabilities like those associated with cancer in humans. This review focuses on recent progress in delineating the mechanism of Rad51-dependent BIR in budding yeast. In addition, we discuss new data that describe changes in BIR efficiency and fidelity on encountering replication obstacles as well as the implications of these findings for BIR-dependent processes such as telomere maintenance and the repair of collapsed replication forks.
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27
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Saponaro M. Transcription-Replication Coordination. Life (Basel) 2022; 12:108. [PMID: 35054503 PMCID: PMC8781949 DOI: 10.3390/life12010108] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/06/2022] [Accepted: 01/10/2022] [Indexed: 12/02/2022] Open
Abstract
Transcription and replication are the two most essential processes that a cell does with its DNA: they allow cells to express the genomic content that is required for their functions and to create a perfect copy of this genomic information to pass on to the daughter cells. Nevertheless, these two processes are in a constant ambivalent relationship. When transcription and replication occupy the same regions, there is the possibility of conflicts between transcription and replication as transcription can impair DNA replication progression leading to increased DNA damage. Nevertheless, DNA replication origins are preferentially located in open chromatin next to actively transcribed regions, meaning that the possibility of conflicts is potentially an accepted incident for cells. Data in the literature point both towards the existence or not of coordination between these two processes to avoid the danger of collisions. Several reviews have been published on transcription-replication conflicts, but we focus here on the most recent findings that relate to how these two processes are coordinated in eukaryotes, considering advantages and disadvantages from coordination, how likely conflicts are at any given time, and which are their potential hotspots in the genome.
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Affiliation(s)
- Marco Saponaro
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
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28
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St Germain C, Zhao H, Sinha V, Sanz LA, Chédin F, Barlow J. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2051-2073. [PMID: 35100392 PMCID: PMC8887484 DOI: 10.1093/nar/gkac035] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 01/05/2022] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
Conflicts between transcription and replication machinery are a potent source of replication stress and genome instability; however, no technique currently exists to identify endogenous genomic locations prone to transcription–replication interactions. Here, we report a novel method to identify genomic loci prone to transcription–replication interactions termed transcription–replication immunoprecipitation on nascent DNA sequencing, TRIPn-Seq. TRIPn-Seq employs the sequential immunoprecipitation of RNA polymerase 2 phosphorylated at serine 5 (RNAP2s5) followed by enrichment of nascent DNA previously labeled with bromodeoxyuridine. Using TRIPn-Seq, we mapped 1009 unique transcription–replication interactions (TRIs) in mouse primary B cells characterized by a bimodal pattern of RNAP2s5, bidirectional transcription, an enrichment of RNA:DNA hybrids, and a high probability of forming G-quadruplexes. TRIs are highly enriched at transcription start sites and map to early replicating regions. TRIs exhibit enhanced Replication Protein A association and TRI-associated genes exhibit higher replication fork termination than control transcription start sites, two marks of replication stress. TRIs colocalize with double-strand DNA breaks, are enriched for deletions, and accumulate mutations in tumors. We propose that replication stress at TRIs induces mutations potentially contributing to age-related disease, as well as tumor formation and development.
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Affiliation(s)
- Commodore P St Germain
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
- School of Mathematics and Science, Solano Community College, 4000 Suisun Valley Road, Fairfield, CA 94534, USA
| | - Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Vrishti Sinha
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Lionel A Sanz
- Department of Molecular and Cellular Biology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Jacqueline H Barlow
- To whom correspondence should be addressed. Tel: +1 530 752 9529; Fax: +1 530 752 9014;
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29
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Huang D, Lo T, Merrikh H, Wiggins PA. Characterizing stochastic cell-cycle dynamics in exponential growth. Phys Rev E 2022; 105:014420. [PMID: 35193317 PMCID: PMC9506121 DOI: 10.1103/physreve.105.014420] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Two powerful and complementary experimental approaches are commonly used to study the cell cycle and cell biology: One class of experiments characterizes the statistics (or demographics) of an unsynchronized exponentially growing population, while the other captures cell-cycle dynamics, either by time-lapse imaging of full cell cycles or in bulk experiments on synchronized populations. In this paper, we study the subtle relationship between observations in these two distinct experimental approaches. We begin with an existing model: A single-cell deterministic description of cell-cycle dynamics where cell states (i.e., periods or phases) have precise lifetimes. We then generalize this description to a stochastic model in which the states have stochastic lifetimes, as described by arbitrary probability distribution functions. Our analyses of the demographics of an exponential culture reveal a simple and exact correspondence between the deterministic and stochastic models: The corresponding state ages in the deterministic model are equal to the exponential mean of the age in the stochastic model. An important implication is therefore that the demographics of an exponential culture will be well fit by a deterministic model even if the state timing is stochastic. Although we explore the implications of the models in the context of the Escherichia coli cell cycle, we expect both the models as well as the significance of the exponential-mean lifetimes to find many applications in the quantitative analysis of cell-cycle dynamics in other biological systems.
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Affiliation(s)
- Dean Huang
- Department of Physics, University of Washington, Seattle, WA, 98195
| | - Teresa Lo
- Department of Physics, University of Washington, Seattle, WA, 98195
| | - Houra Merrikh
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37205
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232
| | - Paul A. Wiggins
- Department of Physics, University of Washington, Seattle, WA, 98195
- Department of Bioengineering, University of Washington, Seattle, WA, 98195
- Department of Microbiology, University of Washington, Seattle, WA, 98195
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30
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Wu W, He JN, Lan M, Zhang P, Chu WK. Transcription-Replication Collisions and Chromosome Fragility. Front Genet 2021; 12:804547. [PMID: 34956339 PMCID: PMC8703014 DOI: 10.3389/fgene.2021.804547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Accurate replication of the entire genome is critical for cell division and propagation. Certain regions in the genome, such as fragile sites (common fragile sites, rare fragile sites, early replicating fragile sites), rDNA and telomeres, are intrinsically difficult to replicate, especially in the presence of replication stress caused by, for example, oncogene activation during tumor development. Therefore, these regions are particularly prone to deletions and chromosome rearrangements during tumorigenesis, rendering chromosome fragility. Although, the mechanism underlying their “difficult-to-replicate” nature and genomic instability is still not fully understood, accumulating evidence suggests transcription might be a major source of endogenous replication stress (RS) leading to chromosome fragility. Here, we provide an updated overview of how transcription affects chromosome fragility. Furthermore, we will use the well characterized common fragile sites (CFSs) as a model to discuss pathways involved in offsetting transcription-induced RS at these loci with a focus on the recently discovered atypical DNA synthesis repair pathway Mitotic DNA Synthesis (MiDAS).
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Affiliation(s)
- Wei Wu
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Jing Na He
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
| | - Mengjiao Lan
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Pumin Zhang
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Wai Kit Chu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
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31
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Brüning JG, Marians KJ. Bypass of complex co-directional replication-transcription collisions by replisome skipping. Nucleic Acids Res 2021; 49:9870-9885. [PMID: 34469567 PMCID: PMC8464059 DOI: 10.1093/nar/gkab760] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 12/27/2022] Open
Abstract
Collisions between the replisome and RNA polymerases [RNAP(s)] are the main obstacle to DNA replication. These collisions can occur either head-on or co-directionally with respect to the direction of translocation of both complexes. Whereas head-on collisions require additional factors to be resolved, co-directional collisions are thought to be overcome by the replisome itself using the mRNA transcript as a primer. We show that mRNA takeover is utilized primarily after collisions with single RNAP complexes with short transcripts. Bypass of more complex transcription complexes requires the synthesis of a new primer downstream of the RNAP for the replisome to resume leading-strand synthesis. In both cases, bypass proceeds with displacement of the RNAP. Rep, Mfd, UvrD and RNase H can process the RNAP block and facilitate replisome bypass by promoting the formation of continuous leading strands. Bypass of co-directional RNAP(s) and/or R-loops is determined largely by the length of the obstacle that the replisome needs to traverse: R-loops are about equally as potent obstacles as RNAP arrays if they occupy the same length of the DNA template.
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Affiliation(s)
- Jan-Gert Brüning
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kenneth J Marians
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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32
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Kemiha S, Poli J, Lin YL, Lengronne A, Pasero P. Toxic R-loops: Cause or consequence of replication stress? DNA Repair (Amst) 2021; 107:103199. [PMID: 34399314 DOI: 10.1016/j.dnarep.2021.103199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 01/08/2023]
Abstract
Transcription-replication conflicts (TRCs) represent a potential source of endogenous replication stress (RS) and genomic instability in eukaryotic cells but the mechanisms that underlie this instability remain poorly understood. Part of the problem could come from non-B DNA structures called R-loops, which are formed of a RNA:DNA hybrid and a displaced ssDNA loop. In this review, we discuss different scenarios in which R-loops directly or indirectly interfere with DNA replication. We also present other types of TRCs that may not depend on R-loops to impede fork progression. Finally, we discuss alternative models in which toxic RNA:DNA hybrids form at stalled forks as a consequence - but not a cause - of replication stress and interfere with replication resumption.
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Affiliation(s)
- Samira Kemiha
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Jérôme Poli
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Yea-Lih Lin
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Armelle Lengronne
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France.
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Mfd regulates RNA polymerase association with hard-to-transcribe regions in vivo, especially those with structured RNAs. Proc Natl Acad Sci U S A 2021; 118:2008498118. [PMID: 33443179 DOI: 10.1073/pnas.2008498118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
RNA polymerase (RNAP) encounters various roadblocks during transcription. These obstacles can impede RNAP movement and influence transcription, ultimately necessitating the activity of RNAP-associated factors. One such factor is the bacterial protein Mfd, a highly conserved DNA translocase and evolvability factor that interacts with RNAP. Although Mfd is thought to function primarily in the repair of DNA lesions that stall RNAP, increasing evidence suggests that it may also be important for transcription regulation. However, this is yet to be fully characterized. To shed light on Mfd's in vivo functions, we identified the chromosomal regions where it associates. We analyzed Mfd's impact on RNAP association and transcription regulation genome-wide. We found that Mfd represses RNAP association at many chromosomal regions. We found that these regions show increased RNAP pausing, suggesting that they are hard to transcribe. Interestingly, we noticed that the majority of the regions where Mfd regulates transcription contain highly structured regulatory RNAs. The RNAs identified regulate a myriad of biological processes, ranging from metabolism to transfer RNA regulation to toxin-antitoxin (TA) functions. We found that cells lacking Mfd are highly sensitive to toxin overexpression. Finally, we found that Mfd promotes mutagenesis in at least one toxin gene, suggesting that its function in regulating transcription may promote evolution of certain TA systems and other regions containing strong RNA secondary structures. We conclude that Mfd is an RNAP cofactor that is important, and at times critical, for transcription regulation at hard-to-transcribe regions, especially those that express structured regulatory RNAs.
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Moreno-del Álamo M, Carrasco B, Torres R, Alonso JC. Bacillus subtilis PcrA Helicase Removes Trafficking Barriers. Cells 2021; 10:935. [PMID: 33920686 PMCID: PMC8074105 DOI: 10.3390/cells10040935] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/27/2022] Open
Abstract
Bacillus subtilis PcrA interacts with the RNA polymerase and might contribute to mitigate replication-transcription conflicts (RTCs). We show that PcrA depletion lethality is partially suppressed by rnhB inactivation, but cell viability is significantly reduced by rnhC or dinG inactivation. Following PcrA depletion, cells lacking RnhC or DinG are extremely sensitive to DNA damage. Chromosome segregation is not further impaired by rnhB or dinG inactivation but is blocked by rnhC or recA inactivation upon PcrA depletion. Despite our efforts, we could not construct a ΔrnhC ΔrecA strain. These observations support the idea that PcrA dismantles RTCs. Purified PcrA, which binds single-stranded (ss) DNA over RNA, is a ssDNA-dependent ATPase and preferentially unwinds DNA in a 3'→5'direction. PcrA unwinds a 3'-tailed RNA of an RNA-DNA hybrid significantly faster than that of a DNA substrate. Our results suggest that a replicative stress, caused by mis-incorporated rNMPs, indirectly increases cell viability upon PcrA depletion. We propose that PcrA, in concert with RnhC or DinG, contributes to removing spontaneous or enzyme-driven R-loops, to counteract deleterious trafficking conflicts and preserve to genomic integrity.
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Affiliation(s)
| | | | | | - Juan Carlos Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 28049 Madrid, Spain; (M.M.-d.Á.); (B.C.); (R.T.)
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35
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Balbontín R, Frazão N, Gordo I. DNA Breaks-Mediated Fitness Cost Reveals RNase HI as a New Target for Selectively Eliminating Antibiotic-Resistant Bacteria. Mol Biol Evol 2021; 38:3220-3234. [PMID: 33830249 PMCID: PMC8321526 DOI: 10.1093/molbev/msab093] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Antibiotic resistance often generates defects in bacterial growth called fitness cost. Understanding the causes of this cost is of paramount importance, as it is one of the main determinants of the prevalence of resistances upon reducing antibiotics use. Here we show that the fitness costs of antibiotic resistance mutations that affect transcription and translation in Escherichia coli strongly correlate with DNA breaks, which are generated via transcription–translation uncoupling, increased formation of RNA–DNA hybrids (R-loops), and elevated replication–transcription conflicts. We also demonstrated that the mechanisms generating DNA breaks are repeatedly targeted by compensatory evolution, and that DNA breaks and the cost of resistance can be increased by targeting the RNase HI, which specifically degrades R-loops. We further show that the DNA damage and thus the fitness cost caused by lack of RNase HI function drive resistant clones to extinction in populations with high initial frequency of resistance, both in laboratory conditions and in a mouse model of gut colonization. Thus, RNase HI provides a target specific against resistant bacteria, which we validate using a repurposed drug. In summary, we revealed key mechanisms underlying the fitness cost of antibiotic resistance mutations that can be exploited to specifically eliminate resistant bacteria.
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Affiliation(s)
| | | | - Isabel Gordo
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
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Lang KS, Merrikh H. Topological stress is responsible for the detrimental outcomes of head-on replication-transcription conflicts. Cell Rep 2021; 34:108797. [PMID: 33657379 PMCID: PMC7986047 DOI: 10.1016/j.celrep.2021.108797] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/14/2020] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
Conflicts between the replication and transcription machineries have profound effects on chromosome duplication, genome organization, and evolution across species. Head-on conflicts (lagging-strand genes) are significantly more detrimental than codirectional conflicts (leading-strand genes). The fundamental reason for this difference is unknown. Here, we report that topological stress significantly contributes to this difference. We find that head-on, but not codirectional, conflict resolution requires the relaxation of positive supercoils by the type II topoisomerases DNA gyrase and Topo IV, at least in the Gram-positive model bacterium Bacillus subtilis. Interestingly, our data suggest that after positive supercoil resolution, gyrase introduces excessive negative supercoils at head-on conflict regions, driving pervasive R-loop formation. Altogether, our results reveal a fundamental mechanistic difference between the two types of encounters, addressing a long-standing question in the field of replication-transcription conflicts. Lang and Merrikh show that resolution of head-on, but not codirectional, conflicts between replication and transcription machineries requires type II topoisomerases, suggesting that a fundamental difference between the two types of conflicts is supercoil buildup in DNA. Furthermore, they show that supercoil resolution at head-on conflict regions drives R-loop formation.
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Affiliation(s)
- Kevin S Lang
- Department of Biochemistry, Light Hall, Vanderbilt University, Nashville, TN, USA
| | - Houra Merrikh
- Department of Biochemistry, Light Hall, Vanderbilt University, Nashville, TN, USA.
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Bolotin A, Quinquis B, Roume H, Gohar M, Lereclus D, Sorokin A. Long inverted repeats around the chromosome replication terminus in the model strain Bacillus thuringiensis serovar israelensis BGSC 4Q7. Microb Genom 2020; 6. [PMID: 33180015 PMCID: PMC8116677 DOI: 10.1099/mgen.0.000468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Bacillus thuringiensis serovar israelensis is the most widely used natural biopesticide against mosquito larvae worldwide. Its lineage has been actively studied and a plasmid-free strain, B. thuringiensis serovar israelensis BGSC 4Q7 (4Q7), has been produced. Previous sequencing of the genome of this strain has revealed the persistent presence of a 235 kb extrachromosomal element, pBtic235, which has been shown to be an inducible prophage, although three putative chromosomal prophages have been lost. Moreover, a 492 kb region, potentially including the standard replication terminus, has also been deleted in the 4Q7 strain, indicating an absence of essential genes in this area. We reanalysed the genome coverage distribution of reads for the previously sequenced variant strain, and sequenced two independently maintained samples of the 4Q7 strain. A 553 kb area, close to the 492 kb deletion, was found to be duplicated. This duplication presumably restored the equal sizes of the replichores, and a balanced functioning of replication termination. An analysis of genome assembly graphs revealed a transient association of the host chromosome with the pBtic235 element. This association may play a functional role in the replication of the bacterial chromosome, and the termination of this process in particular. The genome-restructuring events detected may modify the genetic status of cytotoxic or haemolytic toxins, potentially influencing strain virulence. Twelve of the single-nucleotide variants identified in 4Q7 were probably due to the procedure used for strain construction or were present in the precursor of this strain. No sequence variants were found in pBtic235, but the distribution of the corresponding 4Q7 reads indicates a significant difference from counterparts in natural B. thuringiensis serovar israelensis strains, suggesting a duplication or over-replication in 4Q7. Thus, the 4Q7 strain is not a pure plasmid-less offshoot, but a highly genetically modified derivative of its natural ancestor. In addition to potentially influencing virulence, genome-restructuring events can modify the replication termination machinery. These findings have potential implications for the conclusions of virulence studies on 4Q7 as a model, but they also raise interesting fundamental questions about the functioning of the Bacillus genome.
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Affiliation(s)
- Alexander Bolotin
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Benoit Quinquis
- MGP, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Hugo Roume
- MGP, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Michel Gohar
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Didier Lereclus
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Alexei Sorokin
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
- *Correspondence: Alexei Sorokin,
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Brüning JG, Marians KJ. Replisome bypass of transcription complexes and R-loops. Nucleic Acids Res 2020; 48:10353-10367. [PMID: 32926139 PMCID: PMC7544221 DOI: 10.1093/nar/gkaa741] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/22/2020] [Accepted: 08/25/2020] [Indexed: 12/16/2022] Open
Abstract
The vast majority of the genome is transcribed by RNA polymerases. G+C-rich regions of the chromosomes and negative superhelicity can promote the invasion of the DNA by RNA to form R-loops, which have been shown to block DNA replication and promote genome instability. However, it is unclear whether the R-loops themselves are sufficient to cause this instability or if additional factors are required. We have investigated replisome collisions with transcription complexes and R-loops using a reconstituted bacterial DNA replication system. RNA polymerase transcription complexes co-directionally oriented with the replication fork were transient blockages, whereas those oriented head-on were severe, stable blockages. On the other hand, replisomes easily bypassed R-loops on either template strand. Replication encounters with R-loops on the leading-strand template (co-directional) resulted in gaps in the nascent leading strand, whereas lagging-strand template R-loops (head-on) had little impact on replication fork progression. We conclude that whereas R-loops alone can act as transient replication blocks, most genome-destabilizing replication fork stalling likely occurs because of proteins bound to the R-loops.
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Affiliation(s)
- Jan-Gert Brüning
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kenneth J Marians
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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Balzano E, Pelliccia F, Giunta S. Genome (in)stability at tandem repeats. Semin Cell Dev Biol 2020; 113:97-112. [PMID: 33109442 DOI: 10.1016/j.semcdb.2020.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 09/26/2020] [Accepted: 10/10/2020] [Indexed: 12/12/2022]
Abstract
Repeat sequences account for over half of the human genome and represent a significant source of variation that underlies physiological and pathological states. Yet, their study has been hindered due to limitations in short-reads sequencing technology and difficulties in assembly. A important category of repetitive DNA in the human genome is comprised of tandem repeats (TRs), where repetitive units are arranged in a head-to-tail pattern. Compared to other regions of the genome, TRs carry between 10 and 10,000 fold higher mutation rate. There are several mutagenic mechanisms that can give rise to this propensity toward instability, but their precise contribution remains speculative. Given the high degree of homology between these sequences and their arrangement in tandem, once damaged, TRs have an intrinsic propensity to undergo aberrant recombination with non-allelic exchange and generate harmful rearrangements that may undermine the stability of the entire genome. The dynamic mutagenesis at TRs has been found to underlie individual polymorphism associated with neurodegenerative and neuromuscular disorders, as well as complex genetic diseases like cancer and diabetes. Here, we review our current understanding of the surveillance and repair mechanisms operating within these regions, and we describe how alterations in these protective processes can readily trigger mutational signatures found at TRs, ultimately resulting in the pathological correlation between TRs instability and human diseases. Finally, we provide a viewpoint to counter the detrimental effects that TRs pose in light of their selection and conservation, as important drivers of human evolution.
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Affiliation(s)
- Elisa Balzano
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Franca Pelliccia
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Simona Giunta
- The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy.
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40
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Nastasi C, Mannarino L, D’Incalci M. DNA Damage Response and Immune Defense. Int J Mol Sci 2020; 21:E7504. [PMID: 33053746 PMCID: PMC7588887 DOI: 10.3390/ijms21207504] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/08/2020] [Accepted: 10/10/2020] [Indexed: 02/07/2023] Open
Abstract
DNA damage is the cause of numerous human pathologies including cancer, premature aging, and chronic inflammatory conditions. The DNA damage response (DDR), in turn, coordinates DNA damage checkpoint activation and promotes the removal of DNA lesions. In recent years, several studies have shown how the DDR and the immune system are tightly connected, revealing an important crosstalk between the two of them. This interesting interplay has opened up new perspectives in clinical studies for immunological diseases as well as for cancer treatment. In this review, we provide an overview, from cellular to molecular pathways, on how DDR and the immune system communicate and share the crucial commitment of maintaining the genomic fitness.
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Affiliation(s)
- Claudia Nastasi
- Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy;
| | | | - Maurizio D’Incalci
- Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy;
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41
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Simms CL, Yan LL, Qiu JK, Zaher HS. Ribosome Collisions Result in +1 Frameshifting in the Absence of No-Go Decay. Cell Rep 2020; 28:1679-1689.e4. [PMID: 31412239 PMCID: PMC6701860 DOI: 10.1016/j.celrep.2019.07.046] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/17/2019] [Accepted: 07/15/2019] [Indexed: 12/22/2022] Open
Abstract
During translation, an mRNA is typically occupied by multiple ribosomes sparsely distributed across the coding sequence. This distribution, mediated by slow rates of initiation relative to elongation, ensures that they rarely collide with each other, but given the stochastic nature of protein synthesis, collision events do occur. Recent work from our lab suggested that collisions signal for mRNA degradation through no-go decay (NGD). We have explored the impact of stalling on ribosome function when NGD is compromised and found it to result in +1 frameshifting. We used reporters that limit the number of ribosomes on a transcript to show that +1 frameshifting is induced through ribosome collision in yeast and bacteria. Furthermore, we observe a positive correlation between ribosome density and frameshifting efficiency. It is thus tempting to speculate that NGD, in addition to its role in mRNA quality control, evolved to cope with stochastic collision events to prevent deleterious frameshifting events. Ribosome collisions, resulting from stalling, activate quality control processes to degrade the aberrant mRNA and the incomplete peptide. mRNA degradation proceeds through an endonucleolytic cleavage between the stacked ribosomes, which resolves the collisions. Simms et al. show that, when cleavage is inhibited, colliding ribosomes move out of frame.
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Affiliation(s)
- Carrie L Simms
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Liewei L Yan
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jessica K Qiu
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Hani S Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
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42
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Syeda AH, Dimude JU, Skovgaard O, Rudolph CJ. Too Much of a Good Thing: How Ectopic DNA Replication Affects Bacterial Replication Dynamics. Front Microbiol 2020; 11:534. [PMID: 32351461 PMCID: PMC7174701 DOI: 10.3389/fmicb.2020.00534] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 03/12/2020] [Indexed: 12/15/2022] Open
Abstract
Each cell division requires the complete and accurate duplication of the entire genome. In bacteria, the duplication process of the often-circular chromosomes is initiated at a single origin per chromosome, resulting in two replication forks that traverse the chromosome in opposite directions. DNA synthesis is completed once the two forks fuse in a region diametrically opposite the origin. In some bacteria, such as Escherichia coli, the region where forks fuse forms a specialized termination area. Polar replication fork pause sites flanking this area can pause the progression of replication forks, thereby allowing forks to enter but not to leave. Transcription of all required genes has to take place simultaneously with genome duplication. As both of these genome trafficking processes share the same template, conflicts are unavoidable. In this review, we focus on recent attempts to add additional origins into various ectopic chromosomal locations of the E. coli chromosome. As ectopic origins disturb the native replichore arrangements, the problems resulting from such perturbations can give important insights into how genome trafficking processes are coordinated and the problems that arise if this coordination is disturbed. The data from these studies highlight that head-on replication–transcription conflicts are indeed highly problematic and multiple repair pathways are required to restart replication forks arrested at obstacles. In addition, the existing data also demonstrate that the replication fork trap in E. coli imposes significant constraints to genome duplication if ectopic origins are active. We describe the current models of how replication fork fusion events can cause serious problems for genome duplication, as well as models of how such problems might be alleviated both by a number of repair pathways as well as the replication fork trap system. Considering the problems associated both with head-on replication-transcription conflicts as well as head-on replication fork fusion events might provide clues of how these genome trafficking issues have contributed to shape the distinct architecture of bacterial chromosomes.
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Affiliation(s)
- Aisha H Syeda
- Department of Biology, University of York, York, United Kingdom
| | - Juachi U Dimude
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Ole Skovgaard
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Christian J Rudolph
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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43
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Ragu S, Matos-Rodrigues G, Lopez BS. Replication Stress, DNA Damage, Inflammatory Cytokines and Innate Immune Response. Genes (Basel) 2020; 11:E409. [PMID: 32283785 PMCID: PMC7230342 DOI: 10.3390/genes11040409] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 12/21/2022] Open
Abstract
Complete and accurate DNA replication is essential to genome stability maintenance during cellular division. However, cells are routinely challenged by endogenous as well as exogenous agents that threaten DNA stability. DNA breaks and the activation of the DNA damage response (DDR) arising from endogenous replication stress have been observed at pre- or early stages of oncogenesis and senescence. Proper detection and signalling of DNA damage are essential for the autonomous cellular response in which the DDR regulates cell cycle progression and controls the repair machinery. In addition to this autonomous cellular response, replicative stress changes the cellular microenvironment, activating the innate immune response that enables the organism to protect itself against the proliferation of damaged cells. Thereby, the recent descriptions of the mechanisms of the pro-inflammatory response activation after replication stress, DNA damage and DDR defects constitute important conceptual novelties. Here, we review the links of replication, DNA damage and DDR defects to innate immunity activation by pro-inflammatory paracrine effects, highlighting the implications for human syndromes and immunotherapies.
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Affiliation(s)
| | | | - Bernard S. Lopez
- Institut Cochin, INSERM U1016, UMR 8104 CNRS, Université de Paris, Equipe Labellisée Ligue Contre le Cancer, 24 rue du Faubourg St Jacques, 75014 Paris, France; (S.R.); (G.M.-R.)
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44
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Tanaka H, Watanabe T. Mechanisms Underlying Recurrent Genomic Amplification in Human Cancers. Trends Cancer 2020; 6:462-477. [PMID: 32383436 DOI: 10.1016/j.trecan.2020.02.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 12/17/2022]
Abstract
Focal copy-number increases (genomic amplification) pinpoint oncogenic driver genes and therapeutic targets in cancer genomes. With the advent of genomic technologies, recurrent genomic amplification has been mapped throughout the genome. Recurrent amplification could be solely due to positive selection for the tumor-promoting effects of amplified gene products. Alternatively, recurrence could result from the susceptibility of the loci to amplification. Distinguishing between these possibilities requires a full understanding of the amplification mechanisms. Two mechanisms, the formation of double minute (DM) chromosomes and breakage-fusion-bridge (BFB) cycles, have been repeatedly linked to genomic amplification, and the impact of both mechanisms has been confirmed in cancer genomics data. We review the details of these mechanisms and discuss the mechanisms underlying recurrence.
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Affiliation(s)
- Hisashi Tanaka
- Department of Surgery, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Biomedical Sciences, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA.
| | - Takaaki Watanabe
- Department of Surgery, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Molecular Life Science, Tokai University School of Medicine, Kanagawa, Japan
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45
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Tramontano A, Boffo FL, Russo G, De Rosa M, Iodice I, Pezone A. Methylation of the Suppressor Gene p16INK4a: Mechanism and Consequences. Biomolecules 2020; 10:biom10030446. [PMID: 32183138 PMCID: PMC7175352 DOI: 10.3390/biom10030446] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 12/15/2022] Open
Abstract
Tumor suppressor genes in the CDKN2A/B locus (p15INK4b, p16INK4a, and p14ARF) function as biological barriers to transformation and are the most frequently silenced or deleted genes in human cancers. This gene silencing frequently occurs due to DNA methylation of the promoter regions, although the underlying mechanism is currently unknown. We present evidence that methylation of p16INK4a promoter is associated with DNA damage caused by interference between transcription and replication processes. Inhibition of replication or transcription significantly reduces the DNA damage and CpGs methylation of the p16INK4a promoter. We conclude that de novo methylation of the promoter regions is dependent on local DNA damage. DNA methylation reduces the expression of p16INK4a and ultimately removes this barrier to oncogene-induced senescence.
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Affiliation(s)
- Alfonso Tramontano
- Department of Precision Medicine University of Campania “L. Vanvitelli”, 80131 Naples, Italy;
| | - Francesca Ludovica Boffo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy; (F.L.B.); (G.R.); (M.D.R.); (I.I.)
| | - Giusi Russo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy; (F.L.B.); (G.R.); (M.D.R.); (I.I.)
| | - Mariarosaria De Rosa
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy; (F.L.B.); (G.R.); (M.D.R.); (I.I.)
| | - Ilaria Iodice
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy; (F.L.B.); (G.R.); (M.D.R.); (I.I.)
| | - Antonio Pezone
- Department of Precision Medicine University of Campania “L. Vanvitelli”, 80131 Naples, Italy;
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Istituto di Endocrinologia ed Oncologia Sperimentale del C.N.R., Università Federico II, 80131 Napoli, Italy; (F.L.B.); (G.R.); (M.D.R.); (I.I.)
- Correspondence: or ; Tel.: +39-0817-463-614
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46
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Tumor treating fields cause replication stress and interfere with DNA replication fork maintenance: Implications for cancer therapy. Transl Res 2020; 217:33-46. [PMID: 31707040 DOI: 10.1016/j.trsl.2019.10.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/27/2019] [Accepted: 10/15/2019] [Indexed: 12/20/2022]
Abstract
Tumor treating fields (TTFields) is a noninvasive physical modality of cancer therapy that applies low-intensity, intermediate frequency, and alternating electric fields to a tumor. Interference with mitosis was the first mechanism describing the effects of TTFields on cancer cells; however, TTFields was shown to not only reduce the rejoining of radiation-induced DNA double-strand breaks (DSBs), but to also induce DNA DSBs. The mechanism(s) by which TTFields generates DNA DSBs is related to the generation of replication stress including reduced expression of the DNA replication complex genes MCM6 and MCM10 and the Fanconi's Anemia pathway genes. When markers of DNA replication stress as a result of TTFields exposure were examined, newly replicated DNA length was reduced with TTFields exposure time and there was increased R-loop formation. Furthermore, as cells were exposed to TTFields a conditional vulnerability environment developed which rendered cells more susceptible to DNA damaging agents or agents that interfere with DNA repair or replication fork maintenance. The effect of TTFields exposure with concomitant exposure to cisplatin or PARP inhibition, the combination of TTFields plus concomitant PARP inhibition followed by radiation, or radiation alone at the end of a TTFields exposure were all synergistic. Finally, gene expression analysis of 47 key mitosis regulator genes suggested that TTFields-induced mitotic aberrations and DNA damage/replication stress events, although intimately linked to one another, are likely initiated independently of one another. This suggests that enhanced replication stress and reduced DNA repair capacity are also major mechanisms of TTFields effects, effects for which there are therapeutic implications.
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47
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Determinants of Replication-Fork Pausing at tRNA Genes in Saccharomyces cerevisiae. Genetics 2020; 214:825-838. [PMID: 32071194 DOI: 10.1534/genetics.120.303092] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 02/12/2020] [Indexed: 12/21/2022] Open
Abstract
Transfer RNA (tRNA) genes are widely studied sites of replication-fork pausing and genome instability in the budding yeast Saccharomyces cerevisiae tRNAs are extremely highly transcribed and serve as constitutive condensin binding sites. tRNA transcription by RNA polymerase III has previously been identified as stimulating replication-fork pausing at tRNA genes, but the nature of the block to replication has not been incontrovertibly demonstrated. Here, we describe a systematic, genome-wide analysis of the contributions of candidates to replication-fork progression at tDNAs in yeast: transcription factor binding, transcription, topoisomerase activity, condensin-mediated clustering, and Rad18-dependent DNA repair. We show that an asymmetric block to replication is maintained even when tRNA transcription is abolished by depletion of one or more subunits of RNA polymerase III. By contrast, analogous depletion of the essential transcription factor TFIIIB removes the obstacle to replication. Therefore, our data suggest that the RNA polymerase III transcription complex itself represents an asymmetric obstacle to replication even in the absence of RNA synthesis. We additionally demonstrate that replication-fork progression past tRNA genes is unaffected by the global depletion of condensin from the nucleus, and can be stimulated by the removal of topoisomerases or Rad18-dependent DNA repair pathways.
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48
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Hawkins M, Dimude JU, Howard JAL, Smith AJ, Dillingham MS, Savery NJ, Rudolph CJ, McGlynn P. Direct removal of RNA polymerase barriers to replication by accessory replicative helicases. Nucleic Acids Res 2019; 47:5100-5113. [PMID: 30869136 PMCID: PMC6547429 DOI: 10.1093/nar/gkz170] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/22/2019] [Accepted: 03/08/2019] [Indexed: 11/24/2022] Open
Abstract
Bacterial genome duplication and transcription require simultaneous access to the same DNA template. Conflicts between the replisome and transcription machinery can lead to interruption of DNA replication and loss of genome stability. Pausing, stalling and backtracking of transcribing RNA polymerases add to this problem and present barriers to replisomes. Accessory helicases promote fork movement through nucleoprotein barriers and exist in viruses, bacteria and eukaryotes. Here, we show that stalled Escherichia coli transcription elongation complexes block reconstituted replisomes. This physiologically relevant block can be alleviated by the accessory helicase Rep or UvrD, resulting in the formation of full-length replication products. Accessory helicase action during replication-transcription collisions therefore promotes continued replication without leaving gaps in the DNA. In contrast, DinG does not promote replisome movement through stalled transcription complexes in vitro. However, our data demonstrate that DinG operates indirectly in vivo to reduce conflicts between replication and transcription. These results suggest that Rep and UvrD helicases operate on DNA at the replication fork whereas DinG helicase acts via a different mechanism.
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Affiliation(s)
- Michelle Hawkins
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK
| | - Juachi U Dimude
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | | | - Abigail J Smith
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Mark S Dillingham
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Nigel J Savery
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Christian J Rudolph
- Division of Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Peter McGlynn
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK
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49
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Babos KN, Galloway KE, Kisler K, Zitting M, Li Y, Shi Y, Quintino B, Chow RH, Zlokovic BV, Ichida JK. Mitigating Antagonism between Transcription and Proliferation Allows Near-Deterministic Cellular Reprogramming. Cell Stem Cell 2019; 25:486-500.e9. [PMID: 31523028 DOI: 10.1016/j.stem.2019.08.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 05/24/2019] [Accepted: 08/09/2019] [Indexed: 12/30/2022]
Abstract
Although cellular reprogramming enables the generation of new cell types for disease modeling and regenerative therapies, reprogramming remains a rare cellular event. By examining reprogramming of fibroblasts into motor neurons and multiple other somatic lineages, we find that epigenetic barriers to conversion can be overcome by endowing cells with the ability to mitigate an inherent antagonism between transcription and DNA replication. We show that transcription factor overexpression induces unusually high rates of transcription and that sustaining hypertranscription and transgene expression in hyperproliferative cells early in reprogramming is critical for successful lineage conversion. However, hypertranscription impedes DNA replication and cell proliferation, processes that facilitate reprogramming. We identify a chemical and genetic cocktail that dramatically increases the number of cells capable of simultaneous hypertranscription and hyperproliferation by activating topoisomerases. Further, we show that hypertranscribing, hyperproliferating cells reprogram at 100-fold higher, near-deterministic rates. Therefore, relaxing biophysical constraints overcomes molecular barriers to cellular reprogramming.
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Affiliation(s)
- Kimberley N Babos
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA; Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Kate E Galloway
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA; Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
| | - Kassandra Kisler
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Madison Zitting
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yichen Li
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yingxiao Shi
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA
| | - Brooke Quintino
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA
| | - Robert H Chow
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Berislav V Zlokovic
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Justin K Ichida
- Eli and Edythe Broad CIRM Center, University of Southern California, 1425 San Pablo Street, Los Angeles, CA 90033, USA; Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA, USA; Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
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50
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Perera HM, Behrmann MS, Hoang JM, Griffin WC, Trakselis MA. Contacts and context that regulate DNA helicase unwinding and replisome progression. Enzymes 2019; 45:183-223. [PMID: 31627877 DOI: 10.1016/bs.enz.2019.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hexameric DNA helicases involved in the separation of duplex DNA at the replication fork have a universal architecture but have evolved from two separate protein families. The consequences are that the regulation, translocation polarity, strand specificity, and architectural orientation varies between phage/bacteria to that of archaea/eukaryotes. Once assembled and activated for single strand DNA translocation and unwinding, the DNA polymerase couples tightly to the helicase forming a robust replisome complex. However, this helicase-polymerase interaction can be challenged by various forms of endogenous or exogenous agents that can stall the entire replisome or decouple DNA unwinding from synthesis. The consequences of decoupling can be severe, leading to a build-up of ssDNA requiring various pathways for replication fork restart. All told, the hexameric helicase sits prominently at the front of the replisome constantly responding to a variety of obstacles that require transient unwinding/reannealing, traversal of more stable blocks, and alternations in DNA unwinding speed that regulate replisome progression.
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Affiliation(s)
- Himasha M Perera
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Megan S Behrmann
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Joy M Hoang
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Wezley C Griffin
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States.
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