1
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Jia C, Chai R, Zhang M, Guo X, Zhou X, Ding N, Lei C, Dong Z, Zhao J, Ren H, Lu D. Improvement of Saccharomyces cerevisiae strain tolerance to vanillin through heavy ion radiation combined with adaptive laboratory evolution. J Biotechnol 2024; 394:112-124. [PMID: 39197754 DOI: 10.1016/j.jbiotec.2024.08.014] [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: 06/05/2024] [Revised: 08/12/2024] [Accepted: 08/23/2024] [Indexed: 09/01/2024]
Abstract
Vanillin is an inhibitor of lignocellulose hydrolysate, which can reduce the ability of Saccharomyces cerevisiae to utilize lignocellulose, which is an important factor limiting the development of the ethanol fermentation industry. In this study, mutants of vanillin-tolerant yeast named H6, H7, X3, and X8 were bred by heavy ion irradiation (HIR) combined with adaptive laboratory evolution (ALE). Phenotypic tests revealed that the mutants outperformed the original strain WT in tolerance, growth rate, genetic stability and fermentation ability. At 1.6 g/L vanillin concentration, the average OD600 value obtained for mutant strains was 0.95 and thus about 3.4-fold higher than for the wild-type. When the concentration of vanillin was 2.0 g/L, the glucose utilization rate of the mutant was 86.3 % within 96 h, while that of the original strain was only 70.0 %. At this concentration of vanillin, the mitochondrial membrane potential of the mutant strain recovered faster than that of the original strain, and the ROS scavenging ability was stronger. We analyzed the whole transcriptome sequencing map and the whole genome resequencing of the mutant, and found that DEGs such as FLO9, GRC3, PSP2 and SWF1, which have large differential expression multiples and obvious mutation characteristics, play an important role in cell flocculation, rDNA transcription, inhibition of DNA polymerase mutation and protein palmitoylation. These functions can help cells resist vanillin stress. The results show that combining HIR with ALE is an effective mutagenesis strategy. This approach can efficiently obtain Saccharomyces cerevisiae mutants with improved vanillin tolerance, and provide reference for obtaining robust yeast strains with lignocellulose inhibitor tolerance.
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Affiliation(s)
- Chenglin Jia
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ran Chai
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
| | - Miaomiao Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaopeng Guo
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
| | - Xiang Zhou
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nan Ding
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cairong Lei
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ziyi Dong
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingru Zhao
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiwei Ren
- School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
| | - Dong Lu
- Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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2
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Grzechnik P, Mischo H. Fateful decisions of where to cut the line: Pathology associated with aberrant 3' end processing and transcription termination. J Mol Biol 2024:168802. [PMID: 39321865 DOI: 10.1016/j.jmb.2024.168802] [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: 07/31/2024] [Revised: 09/17/2024] [Accepted: 09/19/2024] [Indexed: 09/27/2024]
Abstract
Aberrant gene expression lies at the heart of many pathologies. This review will point out how 3' end processing, the final mRNA-maturation step in the transcription cycle, is surprisingly prone to regulated as well as stochastic variations with a wide range of consequences. Whereas smaller variations contribute to the plasticity of gene expression, larger alternations to 3' end processing and coupled transcription termination can lead to pathological consequences. These can be caused by the local mutation of one gene or affect larger numbers of genes systematically, if aspects of the mechanisms of 3' end processing and transcription termination are altered.
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Affiliation(s)
- Pawel Grzechnik
- Division of Molecular and Cellular Function, School of Biological Sciences, University of Manchester
| | - Hannah Mischo
- Department of Infectious Diseases, School of Immunology and Microbial Science, King's College London
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3
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Luna R, Gómez-González B, Aguilera A. RNA biogenesis and RNA metabolism factors as R-loop suppressors: a hidden role in genome integrity. Genes Dev 2024; 38:504-527. [PMID: 38986581 PMCID: PMC11293400 DOI: 10.1101/gad.351853.124] [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: 07/12/2024]
Abstract
Genome integrity relies on the accuracy of DNA metabolism, but as appreciated for more than four decades, transcription enhances mutation and recombination frequencies. More recent research provided evidence for a previously unforeseen link between RNA and DNA metabolism, which is often related to the accumulation of DNA-RNA hybrids and R-loops. In addition to physiological roles, R-loops interfere with DNA replication and repair, providing a molecular scenario for the origin of genome instability. Here, we review current knowledge on the multiple RNA factors that prevent or resolve R-loops and consequent transcription-replication conflicts and thus act as modulators of genome dynamics.
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Affiliation(s)
- Rosa Luna
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Belén Gómez-González
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain;
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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4
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Kannan A, Gangadharan Leela S, Branzei D, Gangwani L. Role of senataxin in R-loop-mediated neurodegeneration. Brain Commun 2024; 6:fcae239. [PMID: 39070547 PMCID: PMC11277865 DOI: 10.1093/braincomms/fcae239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 06/14/2024] [Accepted: 07/13/2024] [Indexed: 07/30/2024] Open
Abstract
Senataxin is an RNA:DNA helicase that plays an important role in the resolution of RNA:DNA hybrids (R-loops) formed during transcription. R-loops are involved in the regulation of biological processes such as immunoglobulin class switching, gene expression and DNA repair. Excessive accumulation of R-loops results in DNA damage and loss of genomic integrity. Senataxin is critical for maintaining optimal levels of R-loops to prevent DNA damage and acts as a genome guardian. Within the nucleus, senataxin interacts with various RNA processing factors and DNA damage response and repair proteins. Senataxin interactors include survival motor neuron and zinc finger protein 1, with whom it co-localizes in sub-nuclear bodies. Despite its ubiquitous expression, mutations in senataxin specifically affect neurons and result in distinct neurodegenerative diseases such as amyotrophic lateral sclerosis type 4 and ataxia with oculomotor apraxia type 2, which are attributed to the gain-of-function and the loss-of-function mutations in senataxin, respectively. In addition, low levels of senataxin (loss-of-function) in spinal muscular atrophy result in the accumulation of R-loops causing DNA damage and motor neuron degeneration. Senataxin may play multiple functions in diverse cellular processes; however, its emerging role in R-loop resolution and maintenance of genomic integrity is gaining attention in the field of neurodegenerative diseases. In this review, we highlight the role of senataxin in R-loop resolution and its potential as a therapeutic target to treat neurodegenerative diseases.
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Affiliation(s)
| | - Shyni Gangadharan Leela
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Dana Branzei
- The AIRC Institute of Molecular Oncology Foundation, IFOM ETS, Milan 20139, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia 27100, Italy
| | - Laxman Gangwani
- Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
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5
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Mérida-Cerro JA, Maraver-Cárdenas P, Rondón AG, Aguilera A. Rat1 promotes premature transcription termination at R-loops. Nucleic Acids Res 2024; 52:3623-3635. [PMID: 38281203 DOI: 10.1093/nar/gkae033] [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: 06/05/2023] [Revised: 01/04/2024] [Accepted: 01/10/2024] [Indexed: 01/30/2024] Open
Abstract
Certain DNA sequences can adopt a non-B form in the genome that interfere with DNA-templated processes, including transcription. Among the sequences that are intrinsically difficult to transcribe are those that tend to form R-loops, three-stranded nucleic acid structures formed by a DNA-RNA hybrid and the displaced ssDNA. Here we compared the transcription of an endogenous gene with and without an R-loop-forming sequence inserted. We show that, in agreement with previous in vivo and in vitro analyses, transcription elongation is delayed by R-loops in yeast. Importantly, we demonstrate that the Rat1 transcription terminator factor facilitates transcription throughout such structures by inducing premature termination of arrested RNAPIIs. We propose that RNase H degrades the RNA moiety of the hybrid, providing an entry site for Rat1. Thus, we have uncovered an unanticipated function of Rat1 as a transcription restoring factor opening up the possibility that it may also promote transcription through other genomic DNA structures intrinsically difficult to transcribe. If R-loop-mediated transcriptional stress is not relieved by Rat1, it will cause genomic instability, probably through the increase of transcription-replication conflicts, a deleterious situation that could lead to cancer.
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Affiliation(s)
- José Antonio Mérida-Cerro
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, CSIC, 41092 Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Pablo Maraver-Cárdenas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, CSIC, 41092 Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Ana G Rondón
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, CSIC, 41092 Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, CSIC, 41092 Seville, Spain; Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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6
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Giannini M, Porrua O. Senataxin: A key actor in RNA metabolism, genome integrity and neurodegeneration. Biochimie 2024; 217:10-19. [PMID: 37558082 DOI: 10.1016/j.biochi.2023.08.001] [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: 05/08/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/11/2023]
Abstract
The RNA/DNA helicase senataxin (SETX) has been involved in multiple crucial processes related to genome expression and integrity such us transcription termination, the regulation of transcription-replication conflicts and the resolution of R-loops. SETX has been the focus of numerous studies since the discovery that mutations in its coding gene are the root cause of two different neurodegenerative diseases: Ataxia with Oculomotor Apraxia type 2 (AOA2) and a juvenile form of Amyotrophic Lateral Sclerosis (ALS4). A plethora of cellular phenotypes have been described as the result of SETX deficiency, yet the precise molecular function of SETX as well as the molecular pathways leading from SETX mutations to AOA2 and ALS4 pathologies have remained unclear. However, recent data have shed light onto the biochemical activities and biological roles of SETX, thus providing new clues to understand the molecular consequences of SETX mutation. In this review we summarize near two decades of scientific effort to elucidate SETX function, we discuss strengths and limitations of the approaches and models used thus far to investigate SETX-associated diseases and suggest new possible research avenues for the study of AOA2 and ALS4 pathogenesis.
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Affiliation(s)
- Marta Giannini
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Odil Porrua
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France.
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7
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Normand C, Dez C, Dauban L, Queille S, Danché S, Abderrahmane S, Beckouet F, Gadal O. RNA polymerase I mutant affects ribosomal RNA processing and ribosomal DNA stability. RNA Biol 2024; 21:1-16. [PMID: 39049162 PMCID: PMC11275518 DOI: 10.1080/15476286.2024.2381910] [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] [Revised: 07/12/2024] [Accepted: 07/15/2024] [Indexed: 07/27/2024] Open
Abstract
Transcription is a major contributor to genomic instability. The ribosomal RNA (rDNA) gene locus consists of a head-to-tail repeat of the most actively transcribed genes in the genome. RNA polymerase I (RNAPI) is responsible for massive rRNA production, and nascent rRNA is co-transcriptionally assembled with early assembly factors in the yeast nucleolus. In Saccharomyces cerevisiae, a mutant form of RNAPI bearing a fusion of the transcription factor Rrn3 with RNAPI subunit Rpa43 (CARA-RNAPI) has been described previously. Here, we show that the CARA-RNAPI allele results in a novel type of rRNA processing defect, associated with rDNA genomic instability. A fraction of the 35S rRNA produced in CARA-RNAPI mutant escapes processing steps and accumulates. This accumulation is increased in mutants affecting exonucleolytic activities of the exosome complex. CARA-RNAPI is synthetic lethal with monopolin mutants that are known to affect the rDNA condensation. CARA-RNAPI strongly impacts rDNA organization and increases rDNA copy number variation. Reduced rDNA copy number suppresses lethality, suggesting that the chromosome segregation defect is caused by genomic rDNA instability. We conclude that a constitutive association of Rrn3 with transcribing RNAPI results in the accumulation of rRNAs that escape normal processing, impacting rDNA organization and affecting rDNA stability.
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Affiliation(s)
- Christophe Normand
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Christophe Dez
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Lise Dauban
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Sophie Queille
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Sarah Danché
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Sarra Abderrahmane
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Frederic Beckouet
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Olivier Gadal
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Integrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
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8
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Schwank K, Schmid C, Fremter T, Engel C, Milkereit P, Griesenbeck J, Tschochner H. Features of yeast RNA polymerase I with special consideration of the lobe binding subunits. Biol Chem 2023; 404:979-1002. [PMID: 37823775 DOI: 10.1515/hsz-2023-0184] [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: 04/14/2023] [Accepted: 07/13/2023] [Indexed: 10/13/2023]
Abstract
Ribosomal RNAs (rRNAs) are structural components of ribosomes and represent the most abundant cellular RNA fraction. In the yeast Saccharomyces cerevisiae, they account for more than 60 % of the RNA content in a growing cell. The major amount of rRNA is synthesized by RNA polymerase I (Pol I). This enzyme transcribes exclusively the rRNA gene which is tandemly repeated in about 150 copies on chromosome XII. The high number of transcribed rRNA genes, the efficient recruitment of the transcription machinery and the dense packaging of elongating Pol I molecules on the gene ensure that enough rRNA is generated. Specific features of Pol I and of associated factors confer promoter selectivity and both elongation and termination competence. Many excellent reviews exist about the state of research about function and regulation of Pol I and how Pol I initiation complexes are assembled. In this report we focus on the Pol I specific lobe binding subunits which support efficient, error-free, and correctly terminated rRNA synthesis.
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Affiliation(s)
- Katrin Schwank
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Catharina Schmid
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Tobias Fremter
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Christoph Engel
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Philipp Milkereit
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Joachim Griesenbeck
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
| | - Herbert Tschochner
- Regensburg Center of Biochemistry (RCB), Universität Regensburg, D-93053 Regensburg, Germany
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9
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Yang DL, Huang K, Deng D, Zeng Y, Wang Z, Zhang Y. DNA-dependent RNA polymerases in plants. THE PLANT CELL 2023; 35:3641-3661. [PMID: 37453082 PMCID: PMC10533338 DOI: 10.1093/plcell/koad195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/09/2023] [Accepted: 05/29/2023] [Indexed: 07/18/2023]
Abstract
DNA-dependent RNA polymerases (Pols) transfer the genetic information stored in genomic DNA to RNA in all organisms. In eukaryotes, the typical products of nuclear Pol I, Pol II, and Pol III are ribosomal RNAs, mRNAs, and transfer RNAs, respectively. Intriguingly, plants possess two additional Pols, Pol IV and Pol V, which produce small RNAs and long noncoding RNAs, respectively, mainly for silencing transposable elements. The five plant Pols share some subunits, but their distinct functions stem from unique subunits that interact with specific regulatory factors in their transcription cycles. Here, we summarize recent advances in our understanding of plant nucleus-localized Pols, including their evolution, function, structures, and transcription cycles.
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Affiliation(s)
- Dong-Lei Yang
- National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Kun Huang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Deyin Deng
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang Agriculture and Forestry University, Lin’an, Hangzhou 311300, China
| | - Yuan Zeng
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhenxing Wang
- College of Horticulture, National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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10
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Duval M, Yague-Sanz C, Turowski TW, Petfalski E, Tollervey D, Bachand F. The conserved RNA-binding protein Seb1 promotes cotranscriptional ribosomal RNA processing by controlling RNA polymerase I progression. Nat Commun 2023; 14:3013. [PMID: 37230993 DOI: 10.1038/s41467-023-38826-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 05/16/2023] [Indexed: 05/27/2023] Open
Abstract
Transcription by RNA polymerase I (RNAPI) represents most of the transcriptional activity in eukaryotic cells and is associated with the production of mature ribosomal RNA (rRNA). As several rRNA maturation steps are coupled to RNAPI transcription, the rate of RNAPI elongation directly influences processing of nascent pre-rRNA, and changes in RNAPI transcription rate can result in alternative rRNA processing pathways in response to growth conditions and stress. However, factors and mechanisms that control RNAPI progression by influencing transcription elongation rate remain poorly understood. We show here that the conserved fission yeast RNA-binding protein Seb1 associates with the RNAPI transcription machinery and promotes RNAPI pausing states along the rDNA. The overall faster progression of RNAPI at the rDNA in Seb1-deficient cells impaired cotranscriptional pre-rRNA processing and the production of mature rRNAs. Given that Seb1 also influences pre-mRNA processing by modulating RNAPII progression, our findings unveil Seb1 as a pause-promoting factor for RNA polymerases I and II to control cotranscriptional RNA processing.
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Affiliation(s)
- Maxime Duval
- RNA group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Carlo Yague-Sanz
- RNA group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, QC, Canada
- URPHYM-GEMO, The University of Namur, 5000, Namur, Belgium
| | - Tomasz W Turowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | | | - David Tollervey
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - François Bachand
- RNA group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, QC, Canada.
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11
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Han WY, Hou BH, Lee WC, Chan TC, Lin TH, Chen HM. Arabidopsis mRNA decay landscape shaped by XRN 5'-3' exoribonucleases. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 114:895-913. [PMID: 36987558 DOI: 10.1111/tpj.16181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 02/18/2023] [Accepted: 03/03/2023] [Indexed: 05/27/2023]
Abstract
5'-3' exoribonucleases (XRNs) play crucial roles in the control of RNA processing, quality, and quantity in eukaryotes. Although genome-wide profiling of RNA decay fragments is now feasible, how XRNs shape the plant mRNA degradome remains elusive. Here, we profiled and analyzed the RNA degradomes of Arabidopsis wild-type and mutant plants with defects in XRN activity. Deficiency of nuclear XRN3 or cytoplasmic XRN4 activity but not nuclear XRN2 activity greatly altered Arabidopsis mRNA decay profiles. Short excised linear introns and cleaved pre-mRNA fragments downstream of polyadenylation sites were polyadenylated and stabilized in the xrn3 mutant, demonstrating the unique function of XRN3 in the removal of cleavage remnants from pre-mRNA processing. Further analysis of stabilized XRN3 substrates confirmed that pre-mRNA 3' end cleavage frequently occurs after adenosine. The most abundant decay intermediates in wild-type plants include not only the primary substrates of XRN4 but also the products of XRN4-mediated cytoplasmic decay. An increase in decay intermediates with 5' ends upstream of a consensus motif in the xrn4 mutant suggests that there is an endonucleolytic cleavage mechanism targeting the 3' untranslated regions of many Arabidopsis mRNAs. However, analysis of decay fragments in the xrn4 mutant indicated that, except for microRNA-directed slicing, endonucleolytic cleavage events in the coding sequence rarely result in major decay intermediates. Together, these findings reveal the major substrates and products of nuclear and cytoplasmic XRNs along Arabidopsis transcripts and provide a basis for precise interpretation of RNA degradome data.
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Affiliation(s)
- Wan-Yin Han
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University, Taichung 40227, Taiwan, and Academia Sinica, Taipei, 11529, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, 40227, Taiwan
| | - Bo-Han Hou
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Wen-Chi Lee
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Tze-Ching Chan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Tzu-Hsiang Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Ho-Ming Chen
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University, Taichung 40227, Taiwan, and Academia Sinica, Taipei, 11529, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung, 40227, Taiwan
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12
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Regulation of ribosomal RNA gene copy number, transcription and nucleolus organization in eukaryotes. Nat Rev Mol Cell Biol 2023; 24:414-429. [PMID: 36732602 DOI: 10.1038/s41580-022-00573-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2022] [Indexed: 02/04/2023]
Abstract
One of the first biological machineries to be created seems to have been the ribosome. Since then, organisms have dedicated great efforts to optimize this apparatus. The ribosomal RNA (rRNA) contained within ribosomes is crucial for protein synthesis and maintenance of cellular function in all known organisms. In eukaryotic cells, rRNA is produced from ribosomal DNA clusters of tandem rRNA genes, whose organization in the nucleolus, maintenance and transcription are strictly regulated to satisfy the substantial demand for rRNA required for ribosome biogenesis. Recent studies have elucidated mechanisms underlying the integrity of ribosomal DNA and regulation of its transcription, including epigenetic mechanisms and a unique recombination and copy-number control system to stably maintain high rRNA gene copy number. In this Review, we disucss how the crucial maintenance of rRNA gene copy number through control of gene amplification and of rRNA production by RNA polymerase I are orchestrated. We also discuss how liquid-liquid phase separation controls the architecture and function of the nucleolus and the relationship between rRNA production, cell senescence and disease.
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13
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Xie J, Libri D, Porrua O. Mechanisms of eukaryotic transcription termination at a glance. J Cell Sci 2023; 136:286227. [PMID: 36594557 DOI: 10.1242/jcs.259873] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transcription termination is the final step of a transcription cycle, which induces the release of the transcript at the termination site and allows the recycling of the polymerase for the next round of transcription. Timely transcription termination is critical for avoiding interferences between neighbouring transcription units as well as conflicts between transcribing RNA polymerases (RNAPs) and other DNA-associated processes, such as replication or DNA repair. Understanding the mechanisms by which the very stable transcription elongation complex is dismantled is essential for appreciating how physiological gene expression is maintained and also how concurrent processes that occur synchronously on the DNA are coordinated. Although the strategies employed by the different classes of eukaryotic RNAPs are traditionally considered to be different, novel findings point to interesting commonalities. In this Cell Science at a Glance and the accompanying poster, we review the current understanding about the mechanisms of transcription termination by the three eukaryotic RNAPs.
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Affiliation(s)
- Juanjuan Xie
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Domenico Libri
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Odil Porrua
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
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14
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Karyka E, Berrueta Ramirez N, Webster CP, Marchi PM, Graves EJ, Godena VK, Marrone L, Bhargava A, Ray S, Ning K, Crane H, Hautbergue GM, El-Khamisy SF, Azzouz M. SMN-deficient cells exhibit increased ribosomal DNA damage. Life Sci Alliance 2022; 5:e202101145. [PMID: 35440492 PMCID: PMC9018017 DOI: 10.26508/lsa.202101145] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 04/04/2022] [Accepted: 04/04/2022] [Indexed: 12/26/2022] Open
Abstract
Spinal muscular atrophy, the leading genetic cause of infant mortality, is a motor neuron disease caused by low levels of survival motor neuron (SMN) protein. SMN is a multifunctional protein that is implicated in numerous cytoplasmic and nuclear processes. Recently, increasing attention is being paid to the role of SMN in the maintenance of DNA integrity. DNA damage and genome instability have been linked to a range of neurodegenerative diseases. The ribosomal DNA (rDNA) represents a particularly unstable locus undergoing frequent breakage. Instability in rDNA has been associated with cancer, premature ageing syndromes, and a number of neurodegenerative disorders. Here, we report that SMN-deficient cells exhibit increased rDNA damage leading to impaired ribosomal RNA synthesis and translation. We also unravel an interaction between SMN and RNA polymerase I. Moreover, we uncover an spinal muscular atrophy motor neuron-specific deficiency of DDX21 protein, which is required for resolving R-loops in the nucleolus. Taken together, our findings suggest a new role of SMN in rDNA integrity.
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Affiliation(s)
- Evangelia Karyka
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Nelly Berrueta Ramirez
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Department of Molecular Biology and Biotechnology, The Institute of Neuroscience and the Healthy Lifespan Institute, School of Bioscience, Firth Court, University of Sheffield, Sheffield, UK
| | - Christopher P Webster
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Paolo M Marchi
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Emily J Graves
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Vinay K Godena
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Lara Marrone
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Anushka Bhargava
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Swagat Ray
- Department of Molecular Biology and Biotechnology, The Institute of Neuroscience and the Healthy Lifespan Institute, School of Bioscience, Firth Court, University of Sheffield, Sheffield, UK
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln, UK
| | - Ke Ning
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Hannah Crane
- Department of Molecular Biology and Biotechnology, The Institute of Neuroscience and the Healthy Lifespan Institute, School of Bioscience, Firth Court, University of Sheffield, Sheffield, UK
| | - Guillaume M Hautbergue
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Sherif F El-Khamisy
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Department of Molecular Biology and Biotechnology, The Institute of Neuroscience and the Healthy Lifespan Institute, School of Bioscience, Firth Court, University of Sheffield, Sheffield, UK
- The Institute of Cancer Therapeutics, University of Bradford, Bradford, UK
| | - Mimoun Azzouz
- The Healthy Lifespan Institute and Neuroscience Institute, Neurodegeneration and Genome Stability Group, University of Sheffield, Sheffield, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
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15
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Xie J, Aiello U, Clement Y, Haidara N, Girbig M, Schmitzova J, Pena V, Müller CW, Libri D, Porrua O. An integrated model for termination of RNA polymerase III transcription. SCIENCE ADVANCES 2022; 8:eabm9875. [PMID: 35857496 PMCID: PMC9278858 DOI: 10.1126/sciadv.abm9875] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
RNA polymerase III (RNAPIII) synthesizes essential and abundant noncoding RNAs such as transfer RNAs. Controlling RNAPIII span of activity by accurate and efficient termination is a challenging necessity to ensure robust gene expression and to prevent conflicts with other DNA-associated machineries. The mechanism of RNAPIII termination is believed to be simpler than that of other eukaryotic RNA polymerases, solely relying on the recognition of a T-tract in the nontemplate strand. Here, we combine high-resolution genome-wide analyses and in vitro transcription termination assays to revisit the mechanism of RNAPIII transcription termination in budding yeast. We show that T-tracts are necessary but not always sufficient for termination and that secondary structures of the nascent RNAs are important auxiliary cis-acting elements. Moreover, we show that the helicase Sen1 plays a key role in a fail-safe termination pathway. Our results provide a comprehensive model illustrating how multiple mechanisms cooperate to ensure efficient RNAPIII transcription termination.
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Affiliation(s)
- Juanjuan Xie
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Yves Clement
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Nouhou Haidara
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Mathias Girbig
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, 69117 Heidelberg, Germany
- Joint PhD degree from EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jana Schmitzova
- Max Planck Institute for Biophysical Chemistry, Macromolecular Crystallography, Am Fassberg 11, 37077 Goettingen, Germany
| | - Vladimir Pena
- Max Planck Institute for Biophysical Chemistry, Macromolecular Crystallography, Am Fassberg 11, 37077 Goettingen, Germany
| | - Christoph W. Müller
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Corresponding author. (D.L.); (O.P.)
| | - Odil Porrua
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Corresponding author. (D.L.); (O.P.)
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16
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Aiello U, Challal D, Wentzinger G, Lengronne A, Appanah R, Pasero P, Palancade B, Libri D. Sen1 is a key regulator of transcription-driven conflicts. Mol Cell 2022; 82:2952-2966.e6. [PMID: 35839782 DOI: 10.1016/j.molcel.2022.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/04/2022] [Accepted: 06/13/2022] [Indexed: 10/17/2022]
Abstract
Cellular homeostasis requires the coordination of several machineries concurrently engaged in the DNA. Wide-spread transcription can interfere with other processes, and transcription-replication conflicts (TRCs) threaten genome stability. The conserved Sen1 helicase not only terminates non-coding transcription but also interacts with the replisome and reportedly resolves genotoxic R-loops. Sen1 prevents genomic instability, but how this relates to its molecular functions remains unclear. We generated high-resolution, genome-wide maps of transcription-dependent conflicts and R-loops using a Sen1 mutant that has lost interaction with the replisome but is termination proficient. We show that, under physiological conditions, Sen1 removes RNA polymerase II at TRCs within genes and the rDNA and at sites of transcription-transcription conflicts, thus qualifying as a "key regulator of conflicts." We demonstrate that genomic stability is affected by Sen1 mutation only when in addition to its role at the replisome, the termination of non-coding transcription or R-loop removal are additionally compromised.
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Affiliation(s)
- Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France
| | - Drice Challal
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France
| | | | - Armelle Lengronne
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Rowin Appanah
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Benoit Palancade
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013 Paris, France.
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17
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Nojima T, Proudfoot NJ. Mechanisms of lncRNA biogenesis as revealed by nascent transcriptomics. Nat Rev Mol Cell Biol 2022; 23:389-406. [DOI: 10.1038/s41580-021-00447-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2021] [Indexed: 12/14/2022]
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18
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Defining the Influence of the A12.2 Subunit on Transcription Elongation and Termination by RNA Polymerase I In Vivo. Genes (Basel) 2021; 12:genes12121939. [PMID: 34946888 PMCID: PMC8701712 DOI: 10.3390/genes12121939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
Saccharomyces cerevisiae has approximately 200 copies of the 35S rDNA gene, arranged tandemly on chromosome XII. This gene is transcribed by RNA polymerase I (Pol I) and the 35S rRNA transcript is processed to produce three of the four rRNAs required for ribosome biogenesis. An intergenic spacer (IGS) separates each copy of the 35S gene and contains the 5S rDNA gene, the origin of DNA replication, and the promoter for the adjacent 35S gene. Pol I is a 14-subunit enzyme responsible for the majority of rRNA synthesis, thereby sustaining normal cellular function and growth. The A12.2 subunit of Pol I plays a crucial role in cleavage, termination, and nucleotide addition during transcription. Deletion of this subunit causes alteration of nucleotide addition kinetics and read-through of transcription termination sites. To interrogate both of these phenomena, we performed native elongating transcript sequencing (NET-seq) with an rpa12Δ strain of S. cerevisiae and evaluated the resultant change in Pol I occupancy across the 35S gene and the IGS. Compared to wild-type (WT), we observed template sequence-specific changes in Pol I occupancy throughout the 35S gene. We also observed rpa12Δ Pol I occupancy downstream of both termination sites and throughout most of the IGS, including the 5S gene. Relative occupancy of rpa12Δ Pol I increased upstream of the promoter-proximal Reb1 binding site and dropped significantly downstream, implicating this site as a third terminator for Pol I transcription. Collectively, these high-resolution results indicate that the A12.2 subunit of Pol I plays an important role in transcription elongation and termination.
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19
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Jurga M, Abugable AA, Goldman ASH, El-Khamisy SF. USP11 controls R-loops by regulating senataxin proteostasis. Nat Commun 2021; 12:5156. [PMID: 34526504 PMCID: PMC8443744 DOI: 10.1038/s41467-021-25459-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
R-loops are by-products of transcription that must be tightly regulated to maintain genomic stability and gene expression. Here, we describe a mechanism for the regulation of the R-loop-specific helicase, senataxin (SETX), and identify the ubiquitin specific peptidase 11 (USP11) as an R-loop regulator. USP11 de-ubiquitinates SETX and its depletion increases SETX K48-ubiquitination and protein turnover. Loss of USP11 decreases SETX steady-state levels and reduces R-loop dissolution. Ageing of USP11 knockout cells restores SETX levels via compensatory transcriptional downregulation of the E3 ubiquitin ligase, KEAP1. Loss of USP11 reduces SETX enrichment at KEAP1 promoter, leading to R-loop accumulation, enrichment of the endonuclease XPF and formation of double-strand breaks. Overexpression of KEAP1 increases SETX K48-ubiquitination, promotes its degradation and R-loop accumulation. These data define a ubiquitination-dependent mechanism for SETX regulation, which is controlled by the opposing activities of USP11 and KEAP1 with broad applications for cancer and neurological disease.
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Affiliation(s)
- Mateusz Jurga
- School of Bioscience, Department of Molecular Biology and Biotechnology, The Healthy Lifespan Institute and the Institute of Neuroscience, University of Sheffield, Sheffield, UK
- The Institute of Cancer Therapeutics, University of Bradford, Bradford, UK
| | - Arwa A Abugable
- School of Bioscience, Department of Molecular Biology and Biotechnology, The Healthy Lifespan Institute and the Institute of Neuroscience, University of Sheffield, Sheffield, UK
| | | | - Sherif F El-Khamisy
- School of Bioscience, Department of Molecular Biology and Biotechnology, The Healthy Lifespan Institute and the Institute of Neuroscience, University of Sheffield, Sheffield, UK.
- The Institute of Cancer Therapeutics, University of Bradford, Bradford, UK.
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20
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Yague-Sanz C, Duval M, Larochelle M, Bachand F. Co-transcriptional RNA cleavage by Drosha homolog Pac1 triggers transcription termination in fission yeast. Nucleic Acids Res 2021; 49:8610-8624. [PMID: 34352089 PMCID: PMC8421224 DOI: 10.1093/nar/gkab654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
Transcription termination of protein-coding genes in eukaryotic cells usually relies on a tight coordination between the cleavage and polyadenylation of the pre-mRNA, and 5′-3′ degradation of the downstream nascent transcript. Here we investigated the contribution of the essential fission yeast endonuclease Pac1, a homolog of human Drosha that cleaves hairpin RNA structures, in triggering polyadenylation-independent transcription termination. Using ChIP-sequencing in Pac1-deficient cells, we found that Pac1 triggers transcription termination at snRNA and snoRNA genes as well as at specific protein-coding genes. Notably, we found that Pac1-dependent premature termination occurred at two genes encoding conserved transmembrane transporters whose expression were strongly repressed by Pac1. Analysis by genome editing indicated that a stem-loop structure in the nascent transcript directs Pac1-mediated cleavage and that the regions upstream and downstream of the Pac1 cleavage site in the targeted mRNAs were stabilized by mutation of nuclear 3′-5′ and 5′-3′ exonucleases, respectively. Our findings unveil a premature transcription termination pathway that uncouples co-transcriptional RNA cleavage from polyadenylation, triggering rapid nuclear RNA degradation.
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Affiliation(s)
- Carlo Yague-Sanz
- RNA Group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke J1E 4K8, Québec, Canada
| | - Maxime Duval
- RNA Group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke J1E 4K8, Québec, Canada
| | - Marc Larochelle
- RNA Group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke J1E 4K8, Québec, Canada
| | - François Bachand
- RNA Group, Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke J1E 4K8, Québec, Canada
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21
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Li M, Klungland A. Modifications and interactions at the R-loop. DNA Repair (Amst) 2020; 96:102958. [PMID: 32961406 DOI: 10.1016/j.dnarep.2020.102958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/24/2020] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
R-loops are tripartite structures consisting of an RNA:DNA hybrid and a displaced single-stranded DNA [1]. They are widespread and occupy up to 5 % of the mammalian genomes [2]. R-loops have a key role in genome stability, and known functions associated with gene regulation, DNA replication, chromatin patterning, immunoglobuline gene recombination and DNA Double-strand break repair [3-7]. Novel methodology, including the application of the S9.6 antibody, have more recently led to detailed knowledge on the genome-wide distribution of the R-loops as well as the identification of the R-loop interactome [8-10]. The regulation of R-loops was recently shown to also depend on dynamic RNA-methylation, including METTL3/14 dependent 6-methylAdenines (m6As) and METTL8 dependent 3-methylCytosines (m3Cs) [11-13].
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Affiliation(s)
- Miaomiao Li
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, NO-0027, Oslo, Norway; Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, NO-0317, Oslo, Norway
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, NO-0027, Oslo, Norway; Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, NO-0317, Oslo, Norway.
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22
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Abraham KJ, Khosraviani N, Chan JNY, Gorthi A, Samman A, Zhao DY, Wang M, Bokros M, Vidya E, Ostrowski LA, Oshidari R, Pietrobon V, Patel PS, Algouneh A, Singhania R, Liu Y, Yerlici VT, De Carvalho DD, Ohh M, Dickson BC, Hakem R, Greenblatt JF, Lee S, Bishop AJR, Mekhail K. Nucleolar RNA polymerase II drives ribosome biogenesis. Nature 2020; 585:298-302. [PMID: 32669707 PMCID: PMC7486236 DOI: 10.1038/s41586-020-2497-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 04/21/2020] [Indexed: 12/16/2022]
Abstract
Proteins are manufactured by ribosomes-macromolecular complexes of protein and RNA molecules that are assembled within major nuclear compartments called nucleoli1,2. Existing models suggest that RNA polymerases I and III (Pol I and Pol III) are the only enzymes that directly mediate the expression of the ribosomal RNA (rRNA) components of ribosomes. Here we show, however, that RNA polymerase II (Pol II) inside human nucleoli operates near genes encoding rRNAs to drive their expression. Pol II, assisted by the neurodegeneration-associated enzyme senataxin, generates a shield comprising triplex nucleic acid structures known as R-loops at intergenic spacers flanking nucleolar rRNA genes. The shield prevents Pol I from producing sense intergenic noncoding RNAs (sincRNAs) that can disrupt nucleolar organization and rRNA expression. These disruptive sincRNAs can be unleashed by Pol II inhibition, senataxin loss, Ewing sarcoma or locus-associated R-loop repression through an experimental system involving the proteins RNaseH1, eGFP and dCas9 (which we refer to as 'red laser'). We reveal a nucleolar Pol-II-dependent mechanism that drives ribosome biogenesis, identify disease-associated disruption of nucleoli by noncoding RNAs, and establish locus-targeted R-loop modulation. Our findings revise theories of labour division between the major RNA polymerases, and identify nucleolar Pol II as a major factor in protein synthesis and nuclear organization, with potential implications for health and disease.
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Affiliation(s)
- Karan J Abraham
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Negin Khosraviani
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Janet N Y Chan
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Aparna Gorthi
- Greehey Children's Cancer Research Institute, Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, USA
| | - Anas Samman
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Dorothy Y Zhao
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Miling Wang
- Sylvester Comprehensive Cancer Center, Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Michael Bokros
- Sylvester Comprehensive Cancer Center, Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Elva Vidya
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Lauren A Ostrowski
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Roxanne Oshidari
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Violena Pietrobon
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Parasvi S Patel
- Princess Margaret Cancer Research Centre, University Health Network, and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Arash Algouneh
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Princess Margaret Cancer Research Centre, University Health Network, and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Rajat Singhania
- Princess Margaret Cancer Research Centre, University Health Network, and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Yupeng Liu
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - V Talya Yerlici
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Daniel D De Carvalho
- Princess Margaret Cancer Research Centre, University Health Network, and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Michael Ohh
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Brendan C Dickson
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Razq Hakem
- Princess Margaret Cancer Research Centre, University Health Network, and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Jack F Greenblatt
- Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Stephen Lee
- Sylvester Comprehensive Cancer Center, Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Alexander J R Bishop
- Greehey Children's Cancer Research Institute, Department of Cell Systems and Anatomy, University of Texas Health at San Antonio, San Antonio, TX, USA
- Mays Cancer Center, University of Texas Health at San Antonio, San Antonio, TX, USA
| | - Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
- Canada Research Chairs Program, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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23
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Roth SJ, Heinz S, Benner C. ARTDeco: automatic readthrough transcription detection. BMC Bioinformatics 2020; 21:214. [PMID: 32456667 PMCID: PMC7249449 DOI: 10.1186/s12859-020-03551-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/18/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Mounting evidence suggests several diseases and biological processes target transcription termination to misregulate gene expression. Disruption of transcription termination leads to readthrough transcription past the 3' end of genes, which can result in novel transcripts, changes in epigenetic states and altered 3D genome structure. RESULTS We developed Automatic Readthrough Transcription Detection (ARTDeco), a tool to detect and analyze multiple features of readthrough transcription from RNA-seq and other next-generation sequencing (NGS) assays that profile transcriptional activity. ARTDeco robustly quantifies the global severity of readthrough phenotypes, and reliably identifies individual genes that fail to terminate (readthrough genes), are aberrantly transcribed due to upstream termination failure (read-in genes), and novel transcripts created as a result of readthrough (downstream of gene or DoG transcripts). We used ARTDeco to characterize readthrough transcription observed during influenza A virus (IAV) infection, validating its specificity and sensitivity by comparing its performance in samples infected with a mutant virus that fails to block transcription termination. We verify ARTDeco's ability to detect readthrough as well as identify read-in genes from different experimental assays across multiple experimental systems with known defects in transcriptional termination, and show how these results can be leveraged to improve the interpretation of gene expression and downstream analysis. Applying ARTDeco to a gene expression data set from IAV-infected monocytes from different donors, we find strong evidence that read-in gene-associated expression quantitative trait loci (eQTLs) likely regulate genes upstream of read-in genes. This indicates that taking readthrough transcription into account is important for the interpretation of eQTLs in systems where transcription termination is blocked. CONCLUSIONS ARTDeco aids researchers investigating readthrough transcription in a variety of systems and contexts.
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Affiliation(s)
- Samuel J Roth
- Bioinformatics and Systems Biology Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0640, USA
| | - Sven Heinz
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0640, USA
| | - Christopher Benner
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0640, USA.
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Campbell JB, Edwards MJ, Ozersky SA, Duina AA. Evidence that dissociation of Spt16 from transcribed genes is partially dependent on RNA Polymerase II termination. Transcription 2019; 10:195-206. [PMID: 31809228 PMCID: PMC6948958 DOI: 10.1080/21541264.2019.1685837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
FACT (FAcilitates Chromatin Transactions) is a highly conserved histone chaperone complex in eukaryotic cells that can interact and manipulate nucleosomes in order to promote a variety of DNA-based processes and to maintain the integrity of chromatin throughout the genome. Whereas key features of the physical interactions that occur between FACT and nucleosomes in vitro have been elucidated in recent years, less is known regarding FACT functional dynamics in vivo. Using the Saccharomyces cerevisiae system, we now provide evidence that at least at some genes dissociation of the FACT subunit Spt16 from their 3′ ends is partially dependent on RNA Polymerase II (Pol II) termination. Combined with other studies, our results are consistent with a two-phase mechanism for FACT dissociation from genes, one that occurs upstream from Pol II dissociation and is Pol II termination-independent and the other that occurs further downstream and is dependent on Pol II termination.
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Affiliation(s)
| | | | | | - Andrea A Duina
- Biology Department, Hendrix College, Conway, Arkansas, USA
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25
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Sáez-Vásquez J, Delseny M. Ribosome Biogenesis in Plants: From Functional 45S Ribosomal DNA Organization to Ribosome Assembly Factors. THE PLANT CELL 2019; 31:1945-1967. [PMID: 31239391 PMCID: PMC6751116 DOI: 10.1105/tpc.18.00874] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 05/28/2019] [Accepted: 06/25/2019] [Indexed: 05/11/2023]
Abstract
The transcription of 18S, 5.8S, and 18S rRNA genes (45S rDNA), cotranscriptional processing of pre-rRNA, and assembly of mature rRNA with ribosomal proteins are the linchpins of ribosome biogenesis. In yeast (Saccharomyces cerevisiae) and animal cells, hundreds of pre-rRNA processing factors have been identified and their involvement in ribosome assembly determined. These studies, together with structural analyses, have yielded comprehensive models of the pre-40S and pre-60S ribosome subunits as well as the largest cotranscriptionally assembled preribosome particle: the 90S/small subunit processome. Here, we present the current knowledge of the functional organization of 45S rDNA, pre-rRNA transcription, rRNA processing activities, and ribosome assembly factors in plants, focusing on data from Arabidopsis (Arabidopsis thaliana). Based on yeast and mammalian cell studies, we describe the ribonucleoprotein complexes and RNA-associated activities and discuss how they might specifically affect the production of 40S and 60S subunits. Finally, we review recent findings concerning pre-rRNA processing pathways and a novel mechanism involved in a ribosome stress response in plants.
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Affiliation(s)
- Julio Sáez-Vásquez
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France, and Universite Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France
| | - Michel Delseny
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France, and Universite Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France
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26
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Pillon MC, Lo YH, Stanley RE. IT'S 2 for the price of 1: Multifaceted ITS2 processing machines in RNA and DNA maintenance. DNA Repair (Amst) 2019; 81:102653. [PMID: 31324529 PMCID: PMC6764878 DOI: 10.1016/j.dnarep.2019.102653] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cells utilize sophisticated RNA processing machines to ensure the quality of RNA. Many RNA processing machines have been further implicated in regulating the DNA damage response signifying a strong link between RNA processing and genome maintenance. One of the most intricate and highly regulated RNA processing pathways is the processing of the precursor ribosomal RNA (pre-rRNA), which is paramount for the production of ribosomes. Removal of the Internal Transcribed Spacer 2 (ITS2), located between the 5.8S and 25S rRNA, is one of the most complex steps of ribosome assembly. Processing of the ITS2 is initiated by the newly discovered endoribonuclease Las1, which cleaves at the C2 site within the ITS2, generating products that are further processed by the polynucleotide kinase Grc3, the 5'→3' exonuclease Rat1, and the 3'→5' RNA exosome complex. In addition to their defined roles in ITS2 processing, these critical cellular machines participate in other stages of ribosome assembly, turnover of numerous cellular RNAs, and genome maintenance. Here we summarize recent work defining the molecular mechanisms of ITS2 processing by these essential RNA processing machines and highlight their emerging roles in transcription termination, heterochromatin function, telomere maintenance, and DNA repair.
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Affiliation(s)
- Monica C Pillon
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Yu-Hua Lo
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Robin E Stanley
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA.
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27
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Rivosecchi J, Larochelle M, Teste C, Grenier F, Malapert A, Ricci EP, Bernard P, Bachand F, Vanoosthuyse V. Senataxin homologue Sen1 is required for efficient termination of RNA polymerase III transcription. EMBO J 2019; 38:e101955. [PMID: 31294478 DOI: 10.15252/embj.2019101955] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/03/2019] [Accepted: 06/11/2019] [Indexed: 01/13/2023] Open
Abstract
R-loop disassembly by the human helicase Senataxin contributes to genome integrity and to proper transcription termination at a subset of RNA polymerase II genes. Whether Senataxin also contributes to transcription termination at other classes of genes has remained unclear. Here, we show that Sen1, one of two fission yeast homologues of Senataxin, promotes efficient termination of RNA polymerase III (RNAP3) transcription in vivo. In the absence of Sen1, RNAP3 accumulates downstream of RNAP3-transcribed genes and produces long exosome-sensitive 3'-extended transcripts. Importantly, neither of these defects was affected by the removal of R-loops. The finding that Sen1 acts as an ancillary factor for RNAP3 transcription termination in vivo challenges the pre-existing view that RNAP3 terminates transcription autonomously. We propose that Sen1 is a cofactor for transcription termination that has been co-opted by different RNA polymerases in the course of evolution.
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Affiliation(s)
- Julieta Rivosecchi
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Marc Larochelle
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Camille Teste
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Frédéric Grenier
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Amélie Malapert
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Emiliano P Ricci
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Pascal Bernard
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - François Bachand
- Département de Biochimie, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Vincent Vanoosthuyse
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, CNRS, UMR 5239, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France
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28
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Abstract
In all living organisms, the flow of genetic information is a two-step process: first DNA is transcribed into RNA, which is subsequently used as template for protein synthesis during translation. In bacteria, archaea and eukaryotes, transcription is carried out by multi-subunit RNA polymerases (RNAPs) sharing a conserved architecture of the RNAP core. RNAPs catalyse the highly accurate polymerisation of RNA from NTP building blocks, utilising DNA as template, being assisted by transcription factors during the initiation, elongation and termination phase of transcription. The complexity of this highly dynamic process is reflected in the intricate network of protein-protein and protein-nucleic acid interactions in transcription complexes and the substantial conformational changes of the RNAP as it progresses through the transcription cycle.In this chapter, we will first briefly describe the early work that led to the discovery of multisubunit RNAPs. We will then discuss the three-dimensional organisation of RNAPs from the bacterial, archaeal and eukaryotic domains of life, highlighting the conserved nature, but also the domain-specific features of the transcriptional apparatus. Another section will focus on transcription factors and their role in regulating the RNA polymerase throughout the different phases of the transcription cycle. This includes a discussion of the molecular mechanisms and dynamic events that govern transcription initiation, elongation and termination.
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29
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Peck SA, Hughes KD, Victorino JF, Mosley AL. Writing a wrong: Coupled RNA polymerase II transcription and RNA quality control. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1529. [PMID: 30848101 PMCID: PMC6570551 DOI: 10.1002/wrna.1529] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/27/2018] [Accepted: 02/07/2019] [Indexed: 12/20/2022]
Abstract
Processing and maturation of precursor RNA species is coupled to RNA polymerase II transcription. Co-transcriptional RNA processing helps to ensure efficient and proper capping, splicing, and 3' end processing of different RNA species to help ensure quality control of the transcriptome. Many improperly processed transcripts are not exported from the nucleus, are restricted to the site of transcription, and are in some cases degraded, which helps to limit any possibility of aberrant RNA causing harm to cellular health. These critical quality control pathways are regulated by the highly dynamic protein-protein interaction network at the site of transcription. Recent work has further revealed the extent to which the processes of transcription and RNA processing and quality control are integrated, and how critically their coupling relies upon the dynamic protein interactions that take place co-transcriptionally. This review focuses specifically on the intricate balance between 3' end processing and RNA decay during transcription termination. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Processing > 3' End Processing RNA Processing > Splicing Mechanisms RNA Processing > Capping and 5' End Modifications.
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Affiliation(s)
- Sarah A Peck
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Katlyn D Hughes
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jose F Victorino
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
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30
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Cortez-Sánchez JL, Cortés-Acosta E, Cueto-Hernández VM, Reyes-Maldonado E, Hernández-Rodríguez C, Villa-Tanaca L, Ibarra JA. Activity and expression of Candida glabrata vacuolar proteases in autophagy-like conditions. FEMS Yeast Res 2019; 18:4828329. [PMID: 29385574 DOI: 10.1093/femsyr/foy006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/26/2018] [Indexed: 11/13/2022] Open
Abstract
Candida glabrata is an emerging opportunistic pathogen that has intrinsic resistance to azoles. During infection or while living as a commensal, it encounters nutritional stresses such as deficiency of carbon or nitrogen sources. Herein, we investigate the expression and activity of PrA, Ape1, Ape3 and CpY vacuolar proteases during these stressful nutrimental conditions. Our findings demonstrate a differential activity profile depending on the addition or lack of carbon, nitrogen or both. Of the four proteases tested, PrA and Ape3 showed a higher activity in the absence of nitrogen. Steady-state RNA levels for all the proteases were also differentially expressed although not always correlated with its activity, suggesting multiple levels of regulation. Microscopy observations of C. glabrata cells subjected to the different conditions showed an increase in the vacuolar volume. Moreover, the presence of ATG8-PE and an increased expression of ATG8 were observed in the yeast under the tested conditions suggesting that C. glabrata is in autophagy stage. Taken together, our results showed that PrA, Ape1, Ape3 and CpY have varying activities and expression depending on whether nitrogen or carbon is added to the media, and that these vacuolar proteases might have a role in the autophagy process.
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Affiliation(s)
- J Luis Cortez-Sánchez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - Elías Cortés-Acosta
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - V Mónica Cueto-Hernández
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - Elba Reyes-Maldonado
- Departamento de Morfología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - César Hernández-Rodríguez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - Lourdes Villa-Tanaca
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
| | - J Antonio Ibarra
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Delegación Miguel Hidalgo, Ciudad de México CP 11340, México
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31
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Abou Elela S, Ji X. Structure and function of Rnt1p: An alternative to RNAi for targeted RNA degradation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1521. [PMID: 30548404 DOI: 10.1002/wrna.1521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/30/2018] [Accepted: 11/15/2018] [Indexed: 12/27/2022]
Abstract
The double-stranded RNA-binding protein (dsRBP) family controls RNA editing, stability, and function in all eukaryotes. The central feature of this family is the recognition of a generic RNA duplex using highly conserved double-stranded RNA-binding domain (dsRBD) that recognizes the characteristic distance between the minor grooves created by the RNA helix. Variations on this theme that confer species and functional specificities have been reported but most dsRBPs retain their capacity to bind generic dsRNA. The ribonuclease III (RNase III) family members fall into four classes, represented by bacterial RNase III, yeast Rnt1p, human Drosha, and human Dicer, respectively. Like all dsRBPs and most members of the RNase III family, Rnt1p has a dsRBD, but unlike most of its kin, it poorly binds to generic RNA helices. Instead, Rnt1p, the only known RNase III expressed in Saccharomyces cerevisiae that lacks the RNAi (RNA interference) machinery, recognizes a specific class of stem-loop structures. To recognize the specific substrates, the dsRBD of Rnt1p is specialized, featuring a αβββααα topology and a sequence-specific RNA-binding motif at the C-terminus. Since the discovery of Rnt1p in 1996, significant progress has been made in studies of its genetics, function, structure, and mechanism of action, explaining the reasons and mechanisms for the increased specificity of this enzyme and its impact on the mechanism of RNA degradation. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Processing > Processing of Small RNAs RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Sherif Abou Elela
- Microbiology and Infectiology Department, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Xinhua Ji
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland
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32
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Analysis of rRNA synthesis using quantitative transcription run-on (qTRO) in yeast. Biotechniques 2018; 65:163-168. [PMID: 30227741 DOI: 10.2144/btn-2018-0073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Comparative transcriptional analyses require appropriate and precise normalization. Here we describe a modified transcription run-on (TRO) method, named quantitative TRO (qTRO), that allows quantification of nascent transcription activity. The most critical improvement it introduces is a new standardization method for RNA isolation and hybridization steps, enabling transcription activity quantification and comparative biological analysis. We used this technique with chromatin immunoprecipitation to investigate RNA polymerase I (RNAPI) transcription activity and its rDNA gene profiles in Saccharomyces cerevisiae. We designed a set of new oligonucleotide probes complementary to nascent ribosomal RNA (rRNA) transcripts and standardized their hybridization strength. The qTRO method could be successfully implemented to study RNAPI transcription in response to oxidative stress and in two mutant strains with impaired rRNA synthesis.
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Cortés-Acosta E, Ibarra JA, Ramírez-Saad H, Vargas-Mendoza CF, Villa-Tanaca L, Hernández-Rodríguez C. Polymorphism in the regulatory regions of genes CgYPS1 and CgYPS7 encoding yapsins in Candida glabrata is associated with changes in expression levels. FEMS Yeast Res 2017; 17:4562591. [PMID: 29069395 DOI: 10.1093/femsyr/fox077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/27/2017] [Indexed: 12/29/2022] Open
Abstract
Candida glabrata is an opportunistic fungus infecting mainly immunocompromised people. Its adherence capacity and exoenzymes contribute to damaging host cells. In particular, the yapsins are a family of aspartyl proteases involved in maturation of proteins and cell wall function, and yapsins 1 and 7, respectively encoded by genes CgYPS1 and CgYPS7, are potential virulence factors. In this study, the polymorphism of regulatory regions and the expression profiles of both genes were compared in C. glabrata clinical strains. The sequence analysis of regulatory regions revealed that the distribution of transcription factor binding sites (TFBSs) was similar, although some TFBSs were not universally distributed. The quantita-tive expression of CgYPS1 and CgYPS7 genes of different C. glabrata strains in rich and poor media was estimated by RT-qPCR. The primary sequences of genes CgYPS1 and CgYPS7 of C. glabrata strains were highly conserved among different strains, but the regulatory regions were polymorphic, harboring different TFBS arrays, and showing differential expression profiles.
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Affiliation(s)
- Elías Cortés-Acosta
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México
| | - José Antonio Ibarra
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México
| | - Hugo Ramírez-Saad
- Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana-Xochimilco, 04960 Ciudad de México
| | - Carlos Fabián Vargas-Mendoza
- Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México
| | - Lourdes Villa-Tanaca
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México
| | - César Hernández-Rodríguez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México
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Groh M, Albulescu LO, Cristini A, Gromak N. Senataxin: Genome Guardian at the Interface of Transcription and Neurodegeneration. J Mol Biol 2016; 429:3181-3195. [PMID: 27771483 DOI: 10.1016/j.jmb.2016.10.021] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/14/2016] [Accepted: 10/15/2016] [Indexed: 12/12/2022]
Abstract
R-loops comprise an RNA/DNA hybrid and a displaced single-stranded DNA. They play crucial biological functions and are implicated in neurological diseases, including ataxias, amyotrophic lateral sclerosis, nucleotide expansion disorders (Friedreich ataxia and fragile X syndrome), and cancer. Currently, it is unclear which mechanisms cause R-loop structures to become pathogenic. The RNA/DNA helicase senataxin (SETX) is one of the best characterised R-loop-binding factors in vivo. Mutations in SETX are linked to two neurodegenerative disorders: ataxia with oculomotor apraxia type 2 (AOA2) and amyotrophic lateral sclerosis type 4 (ALS4). SETX is known to play a role in transcription, neurogenesis, and antiviral response. Here, we review the causes of R-loop dysregulation in neurodegenerative diseases and how these structures contribute to pathomechanisms. We will discuss the importance of SETX as a genome guardian in suppressing aberrant R-loop formation and analyse how SETX mutations can lead to neurodegeneration in AOA2/ALS4. Finally, we will discuss the implications for other R-loop-associated neurodegenerative diseases and point to future therapeutic approaches to treat these disorders.
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Affiliation(s)
- Matthias Groh
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Laura Oana Albulescu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Agnese Cristini
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE, UK.
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35
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Porrua O, Boudvillain M, Libri D. Transcription Termination: Variations on Common Themes. Trends Genet 2016; 32:508-522. [DOI: 10.1016/j.tig.2016.05.007] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 05/28/2016] [Accepted: 05/31/2016] [Indexed: 11/29/2022]
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36
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Abstract
Termination of RNA polymerase II (RNAPII) transcription is a fundamental step of gene expression that involves the release of the nascent transcript and dissociation of RNAPII from the DNA template. As transcription termination is intimately linked to RNA 3' end processing, termination pathways have a key decisive influence on the fate of the transcribed RNA. Quite remarkably, when reaching the 3' end of genes, a substantial fraction of RNAPII fail to terminate transcription, requiring the contribution of alternative or "fail-safe" mechanisms of termination to release the polymerase. This point of view covers redundant mechanisms of transcription termination and how they relate to conventional termination models. In particular, we expand on recent findings that propose a reverse torpedo model of termination, in which the 3'5' exonucleolytic activity of the RNA exosome targets transcription events associated with paused and backtracked RNAPII.
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Affiliation(s)
- Jean-François Lemay
- a Department of Biochemistry ; Faculté de Médecine et des Sciences de la Santé; Université de Sherbrooke; Pavillon de Recherche Appliquée sur le Cancer (PRAC) ; Sherbrooke, Quebec
| | - François Bachand
- a Department of Biochemistry ; Faculté de Médecine et des Sciences de la Santé; Université de Sherbrooke; Pavillon de Recherche Appliquée sur le Cancer (PRAC) ; Sherbrooke, Quebec
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37
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Abstract
Terminating transcription is a highly intricate process for mammalian protein-coding genes. First, the chromatin template slows down transcription at the gene end. Then, the transcript is cleaved at the poly(A) signal to release the messenger RNA. The remaining transcript is selectively unraveled and degraded. This induces critical conformational changes in the heart of the enzyme that trigger termination. Termination can also occur at variable positions along the gene and so prevent aberrant transcript formation or intentionally make different transcripts. These may form multiple messenger RNAs with altered regulatory properties or encode different proteins. Finally, termination can be perturbed to achieve particular cellular needs or blocked in cancer or virally infected cells. In such cases, failure to terminate transcription can spell disaster for the cell.
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Affiliation(s)
- Nick J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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38
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Mosrin-Huaman C, Hervouet-Coste N, Rahmouni AR. Co-transcriptional degradation by the 5'-3' exonuclease Rat1p mediates quality control of HXK1 mRNP biogenesis in S. cerevisiae. RNA Biol 2016; 13:582-92. [PMID: 27124216 DOI: 10.1080/15476286.2016.1181255] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The co-transcriptional biogenesis of export-competent messenger ribonucleoprotein particles (mRNPs) in yeast is under the surveillance of quality control (QC) steps. Aberrant mRNPs resulting from inappropriate or inefficient processing and packaging reactions are detected by the QC system and retained in the nucleus with ensuing elimination of their mRNA component by a mechanism that requires the catalytic activity of Rrp6p, a 3'-5' exonuclease associated with the RNA exosome. In previous studies, we implemented a new experimental approach in which the production of aberrant mRNPs is massively increased upon perturbation of mRNP biogenesis by the RNA-dependent helicase/translocase activity of the bacterial Rho factor expressed in S. cerevisiae. The analyses of a subset of transcripts such as PMA1 led us to substantiate the essential role of Rrp6p in the nuclear mRNP QC and to reveal a functional coordination of the process by Nrd1p. Here, we extended those results by showing that, in contrast to PMA1, Rho-induced aberrant HXK1 mRNPs are targeted for destruction by an Nrd1p- and Rrp6p-independent alternative QC pathway that relies on the 5'-3' exonuclease activity of Rat1p. We show that the degradation of aberrant HXK1 mRNPs by Rat1p occurs co-transcriptionally following decapping by Dcp2p and leads to premature transcription termination. We discuss the possibility that this alternative QC pathway might be linked to the well-known specific features of the HXK1 gene transcription such as its localization at the nuclear periphery and gene loop formation.
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Affiliation(s)
| | | | - A Rachid Rahmouni
- a Centre de Biophysique Moléculaire , Rue Charles Sadron , Orléans , France
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39
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Functional architecture of the Reb1-Ter complex of Schizosaccharomyces pombe. Proc Natl Acad Sci U S A 2016; 113:E2267-76. [PMID: 27035982 DOI: 10.1073/pnas.1525465113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Reb1 ofSchizosaccharomyces pomberepresents a family of multifunctional proteins that bind to specific terminator sites (Ter) and cause polar termination of transcription catalyzed by RNA polymerase I (pol I) and arrest of replication forks approaching the Ter sites from the opposite direction. However, it remains to be investigated whether the same mechanism causes arrest of both DNA transactions. Here, we present the structure of Reb1 as a complex with a Ter site at a resolution of 2.7 Å. Structure-guided molecular genetic analyses revealed that it has distinct and well-defined DNA binding and transcription termination (TTD) domains. The region of the protein involved in replication termination is distinct from the TTD. Mechanistically, the data support the conclusion that transcription termination is not caused by just high affinity Reb1-Ter protein-DNA interactions. Rather, protein-protein interactions between the TTD with the Rpa12 subunit of RNA pol I seem to be an integral part of the mechanism. This conclusion is further supported by the observation that double mutations in TTD that abolished its interaction with Rpa12 also greatly reduced transcription termination thereby revealing a conduit for functional communications between RNA pol I and the terminator protein.
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Gros J, Kumar C, Lynch G, Yadav T, Whitehouse I, Remus D. Post-licensing Specification of Eukaryotic Replication Origins by Facilitated Mcm2-7 Sliding along DNA. Mol Cell 2015; 60:797-807. [PMID: 26656162 DOI: 10.1016/j.molcel.2015.10.022] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/28/2015] [Accepted: 10/09/2015] [Indexed: 12/11/2022]
Abstract
Eukaryotic genomes are replicated from many origin sites that are licensed by the loading of the replicative DNA helicase, Mcm2-7. How eukaryotic origin positions are specified remains elusive. Here we show that, contrary to the bacterial paradigm, eukaryotic replication origins are not irrevocably defined by selection of the helicase loading site, but can shift in position after helicase loading. Using purified proteins we show that DNA translocases, including RNA polymerase, can push budding yeast Mcm2-7 double hexamers along DNA. Displaced Mcm2-7 double hexamers support DNA replication initiation distal to the loading site in vitro. Similarly, in yeast cells that are defective for transcription termination, collisions with RNA polymerase induce a redistribution of Mcm2-7 complexes along the chromosomes, resulting in a corresponding shift in DNA replication initiation sites. These results reveal a eukaryotic origin specification mechanism that departs from the classical replicon model, helping eukaryotic cells to negotiate transcription-replication conflict.
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Affiliation(s)
- Julien Gros
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA
| | - Charanya Kumar
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA
| | - Gerard Lynch
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA
| | - Tejas Yadav
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA; Weill-Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
| | - Iestyn Whitehouse
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center (MSKCC), 1275 York Avenue, New York, NY 10065, USA.
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Santos-Pereira JM, Aguilera A. R loops: new modulators of genome dynamics and function. Nat Rev Genet 2015; 16:583-97. [PMID: 26370899 DOI: 10.1038/nrg3961] [Citation(s) in RCA: 528] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
R loops are nucleic acid structures composed of an RNA-DNA hybrid and a displaced single-stranded DNA. Recently, evidence has emerged that R loops occur more often in the genome and have greater physiological relevance, including roles in transcription and chromatin structure, than was previously predicted. Importantly, however, R loops are also a major threat to genome stability. For this reason, several DNA and RNA metabolism factors prevent R-loop formation in cells. Dysfunction of these factors causes R-loop accumulation, which leads to replication stress, genome instability, chromatin alterations or gene silencing, phenomena that are frequently associated with cancer and a number of genetic diseases. We review the current knowledge of the mechanisms controlling R loops and their putative relationship with disease.
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Affiliation(s)
- José M Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
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Dhir A, Dhir S, Proudfoot NJ, Jopling CL. Microprocessor mediates transcriptional termination of long noncoding RNA transcripts hosting microRNAs. Nat Struct Mol Biol 2015; 22:319-27. [PMID: 25730776 PMCID: PMC4492989 DOI: 10.1038/nsmb.2982] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 02/05/2015] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) play a major part in the post-transcriptional regulation of gene expression. Mammalian miRNA biogenesis begins with cotranscriptional cleavage of RNA polymerase II (Pol II) transcripts by the Microprocessor complex. Although most miRNAs are located within introns of protein-coding transcripts, a substantial minority of miRNAs originate from long noncoding (lnc) RNAs, for which transcript processing is largely uncharacterized. We show, by detailed characterization of liver-specific lnc-pri-miR-122 and genome-wide analysis in human cell lines, that most lncRNA transcripts containing miRNAs (lnc-pri-miRNAs) do not use the canonical cleavage-and-polyadenylation pathway but instead use Microprocessor cleavage to terminate transcription. Microprocessor inactivation leads to extensive transcriptional readthrough of lnc-pri-miRNA and transcriptional interference with downstream genes. Consequently we define a new RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells.
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Affiliation(s)
- Ashish Dhir
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Somdutta Dhir
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Nick J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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43
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Abstract
The RNA polymerase II transcription cycle is often divided into three major stages: initiation, elongation, and termination. Research over the last decade has blurred these divisions and emphasized the tightly regulated transitions that occur as RNA polymerase II synthesizes a transcript from start to finish. Transcription termination, the process that marks the end of transcription elongation, is regulated by proteins that interact with the polymerase, nascent transcript, and/or chromatin template. The failure to terminate transcription can cause accumulation of aberrant transcripts and interfere with transcription at downstream genes. Here, we review the mechanism, regulation, and physiological impact of a termination pathway that targets small noncoding transcripts produced by RNA polymerase II. We emphasize the Nrd1-Nab3-Sen1 pathway in yeast, in which the process has been extensively studied. The importance of understanding small RNA termination pathways is underscored by the need to control noncoding transcription in eukaryotic genomes.
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Affiliation(s)
- Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260;
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Colin J, Candelli T, Porrua O, Boulay J, Zhu C, Lacroute F, Steinmetz LM, Libri D. Roadblock termination by reb1p restricts cryptic and readthrough transcription. Mol Cell 2015; 56:667-80. [PMID: 25479637 DOI: 10.1016/j.molcel.2014.10.026] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 06/09/2014] [Accepted: 10/29/2014] [Indexed: 02/09/2023]
Abstract
Widely transcribed compact genomes must cope with the major challenge of frequent overlapping or concurrent transcription events. Efficient and timely transcription termination is crucial to control pervasive transcription and prevent transcriptional interference. In yeast, transcription termination of RNA polymerase II (RNAPII) occurs via two possible pathways that both require recognition of termination signals on nascent RNA by specific factors. We describe here an additional mechanism of transcription termination for RNAPII and demonstrate its biological significance. We show that the transcriptional activator Reb1p bound to DNA is a roadblock for RNAPII, which pauses and is ubiquitinated, thus triggering termination. Reb1p-dependent termination generates a class of cryptic transcripts that are degraded in the nucleus by the exosome. We also observed transcriptional interference between neighboring genes in the absence of Reb1p. This work demonstrates the importance of roadblock termination for controlling pervasive transcription and preventing transcription through gene regulatory regions.
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Affiliation(s)
- Jessie Colin
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France
| | - Tito Candelli
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France
| | - Odil Porrua
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France
| | - Jocelyne Boulay
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France
| | - Chenchen Zhu
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany
| | - François Lacroute
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, 69117 Heidelberg, Germany; Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Domenico Libri
- Centre de Génétique Moléculaire, CNRS UPR3404, 91190 Gif sur Yvette, France.
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Porrua O, Libri D. Transcription termination and the control of the transcriptome: why, where and how to stop. Nat Rev Mol Cell Biol 2015; 16:190-202. [DOI: 10.1038/nrm3943] [Citation(s) in RCA: 201] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Fernández-Pevida A, Kressler D, de la Cruz J. Processing of preribosomal RNA in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:191-209. [PMID: 25327757 DOI: 10.1002/wrna.1267] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 11/07/2022]
Abstract
Most, if not all RNAs, are transcribed as precursors that require processing to gain functionality. Ribosomal RNAs (rRNA) from all organisms undergo both exo- and endonucleolytic processing. Also, in all organisms, rRNA processing occurs inside large preribosomal particles and is coupled to nucleotide modification, folding of the precursor rRNA (pre-rRNA), and assembly of the ribosomal proteins (r-proteins). In this review, we focus on the processing pathway of pre-rRNAs of cytoplasmic ribosomes in the yeast Saccharomyces cerevisiae, without doubt, the organism where this pathway is best characterized. We summarize the current understanding of the rRNA maturation process, particularly focusing on the pre-rRNA processing sites, the enzymes responsible for the cleavage or trimming reactions and the different mechanisms that monitor and regulate the pathway. Strikingly, the overall order of the various processing steps is reasonably well conserved in eukaryotes, perhaps reflecting common principles for orchestrating the concomitant events of pre-rRNA processing and ribosome assembly.
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Affiliation(s)
- Antonio Fernández-Pevida
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain; Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
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Roles for Pbp1 and caloric restriction in genome and lifespan maintenance via suppression of RNA-DNA hybrids. Dev Cell 2014; 30:177-91. [PMID: 25073155 DOI: 10.1016/j.devcel.2014.05.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 03/13/2014] [Accepted: 05/13/2014] [Indexed: 12/31/2022]
Abstract
Intergenic transcription within repetitive loci such as the ribosomal DNA (rDNA) repeats of yeast commonly triggers aberrant recombination. Major mechanisms suppressing aberrant rDNA recombination rely on chromatin silencing or RNAPII repression at intergenic spacers within the repeats. We find ancient processes operating at rDNA intergenic spacers and other loci to maintain genome stability via repression of RNA-DNA hybrids. The yeast Ataxin-2 protein Pbp1 binds noncoding RNA, suppresses RNA-DNA hybrids, and prevents aberrant rDNA recombination. Repression of RNA-DNA hybrids in Pbp1-deficient cells through RNaseH overexpression, deletion of the G4DNA-stabilizing Stm1, or caloric restriction operating via RNaseH/Pif1 restores rDNA stability. Pbp1 also limits hybrids at non-rDNA G4DNA loci including telomeres. Moreover, cells lacking Pbp1 have a short replicative lifespan that is extended upon hybrid suppression. Thus, we find roles for Pbp1 in genome maintenance and reveal that caloric restriction counteracts Pbp1 deficiencies by engaging RNaseH and Pif1.
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Skourti-Stathaki K, Proudfoot NJ. A double-edged sword: R loops as threats to genome integrity and powerful regulators of gene expression. Genes Dev 2014; 28:1384-96. [PMID: 24990962 PMCID: PMC4083084 DOI: 10.1101/gad.242990.114] [Citation(s) in RCA: 394] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
R loops are three-stranded nucleic acid structures that comprise nascent RNA hybridized with the DNA template, leaving the nontemplate DNA single-stranded. These structures form naturally during transcription even though their persistent formation can have deleterious effects on genome integrity. Interestingly, an increasing number of studies also suggest that R loops function as potential gene expression regulators. Here, Skourti-Stathaki and Proudfoot review the most recent findings about R loops, highlighting their opposite roles in cellular fitness. R loops are three-stranded nucleic acid structures that comprise nascent RNA hybridized with the DNA template, leaving the nontemplate DNA single-stranded. R loops form naturally during transcription even though their persistent formation can be a risky outcome with deleterious effects on genome integrity. On the other hand, over the last few years, an increasingly strong case has been built for R loops as potential regulators of gene expression. Therefore, understanding their function and regulation under these opposite situations is essential to fully characterize the mechanisms that control genome integrity and gene expression. Here we review recent findings about these interesting structures that highlight their opposite roles in cellular fitness.
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Affiliation(s)
| | - Nicholas J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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Turowski TW, Tollervey D. Cotranscriptional events in eukaryotic ribosome synthesis. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 6:129-39. [PMID: 25176256 DOI: 10.1002/wrna.1263] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/16/2014] [Accepted: 07/23/2014] [Indexed: 12/13/2022]
Abstract
Eukaryotic ribosomes are synthesized in a complex, multistep pathway. This begins with transcription of the rDNA genes by a specialized RNA polymerase, accompanied by the cotranscriptional binding of large numbers of ribosome synthesis factors, small nucleolar RNAs and ribosomal proteins. Cleavage of the nascent transcript releases the early pre-40S and pre-60S particles, which acquire export competence in the nucleoplasm prior to translocation through the nuclear pore complexes and final maturation to functional ribosomal subunits in the cytoplasm. This review will focus on the many and complex interactions occurring during pre-rRNA synthesis, particularly in budding yeast in which the pathway is best understood.
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Affiliation(s)
- Tomasz W Turowski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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50
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Saccharomyces cerevisiae Sen1 as a model for the study of mutations in human Senataxin that elicit cerebellar ataxia. Genetics 2014; 198:577-90. [PMID: 25116135 DOI: 10.1534/genetics.114.167585] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The nuclear RNA and DNA helicase Sen1 is essential in the yeast Saccharomyces cerevisiae and is required for efficient termination of RNA polymerase II transcription of many short noncoding RNA genes. However, the mechanism of Sen1 function is not understood. We created a plasmid-based genetic system to study yeast Sen1 in vivo. Using this system, we show that (1) the minimal essential region of Sen1 corresponds to the helicase domain and one of two flanking nuclear localization sequences; (2) a previously isolated terminator readthrough mutation in the Sen1 helicase domain, E1597K, is rescued by a second mutation designed to restore a salt bridge within the first RecA domain; and (3) the human ortholog of yeast Sen1, Senataxin, cannot functionally replace Sen1 in yeast. Guided by sequence homology between the conserved helicase domains of Sen1 and Senataxin, we tested the effects of 13 missense mutations that cosegregate with the inherited disorder ataxia with oculomotor apraxia type 2 on Sen1 function. Ten of the disease mutations resulted in transcription readthrough of at least one of three Sen1-dependent termination elements tested. Our genetic system will facilitate the further investigation of structure-function relationships in yeast Sen1 and its orthologs.
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