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Dey S, Batisse C, Shukla J, Webster MW, Takacs M, Saint-André C, Weixlbaumer A. Structural insights into RNA-mediated transcription regulation in bacteria. Mol Cell 2022; 82:3885-3900.e10. [DOI: 10.1016/j.molcel.2022.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/07/2022] [Accepted: 09/19/2022] [Indexed: 11/06/2022]
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2
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Hsu TY, Hsu LN, Chen SY, Juang BT. MUT-7 Provides Molecular Insight into the Werner Syndrome Exonuclease. Cells 2021; 10:cells10123457. [PMID: 34943966 PMCID: PMC8700014 DOI: 10.3390/cells10123457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/01/2021] [Accepted: 12/05/2021] [Indexed: 11/24/2022] Open
Abstract
Werner syndrome (WS) is a rare recessive genetic disease characterized by premature aging. Individuals with this disorder develop normally during childhood, but their physiological conditions exacerbate the aging process in late adolescence. WS is caused by mutation of the human WS gene (WRN), which encodes two main domains, a 3′-5′ exonuclease and a 3′-5′ helicase. Caenorhabditis elegans expresses human WRN orthologs as two different proteins: MUT-7, which has a 3′-5′ exonuclease domain, and C. elegans WRN-1 (CeWRN-1), which has only helicase domains. These unique proteins dynamically regulate olfactory memory in C. elegans, providing insight into the molecular roles of WRN domains in humans. In this review, we specifically focus on characterizing the function of MUT-7 in small interfering RNA (siRNA) synthesis in the cytoplasm and the roles of siRNA in directing nuclear CeWRN-1 loading onto a heterochromatin complex to induce negative feedback regulation. Further studies on the different contributions of the 3′-5′ exonuclease and helicase domains in the molecular mechanism will provide clues to the accelerated aging processes in WS.
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Affiliation(s)
- Tsung-Yuan Hsu
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan;
- Department of Cell and Tissue Biology, University of California, 513 Parnassus, San Francisco, CA 94143, USA
| | - Ling-Nung Hsu
- Occupational Safety and Health Office, Fu Jen Catholic University Hospital, New Taipei City 243, Taiwan;
| | - Shih-Yu Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan;
| | - Bi-Tzen Juang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan;
- Center for Intelligent Drug Systems and Smart Bio-Devices (IDS2B), National Chiao Tung University, Hsinchu 300, Taiwan
- Correspondence:
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3
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Hornáček M, Kováčik L, Mazel T, Cmarko D, Bártová E, Raška I, Smirnov E. Fluctuations of pol I and fibrillarin contents of the nucleoli. Nucleus 2017. [PMID: 28622108 DOI: 10.1080/19491034.2017.1306160] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Nucleoli are formed on the basis of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). Each NOR contains multiple genes coding for RNAs of the ribosomal particles. The prominent components of the nucleolar ultrastructure, fibrillar centers (FC) and dense fibrillar components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene. In this work, we transfected human-derived cells with GFP-RPA43 (subunit of pol I) and RFP-fibrillarin. Following changes of the fluorescent signals in individual FC/DFC units, we found two kinds of kinetics: 1) the rapid fluctuations with periods of 2-3 min, when the pol I and fibrillarin signals oscillated in anti-phase manner, and the intensities of pol I in the neighboring FC/DFC units did not correlate. 2) fluctuations with periods of 10 to 60 min, in which pol I and fibrillarin signals measured in the same unit did not correlate, but pol I signals in the units belonging to different nucleoli were synchronized. Our data indicate that a complex pulsing activity of transcription as well as early processing is common for ribosomal genes.
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Affiliation(s)
- M Hornáček
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
| | - L Kováčik
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
| | - T Mazel
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
| | - D Cmarko
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
| | - E Bártová
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic.,b Institute of Biophysics of the CAS , Brno , Czech Republic
| | - I Raška
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
| | - E Smirnov
- a Institute of Biology and Medical Genetics, First Faculty of Medicine , Charles University, and General University Hospital in Prague , Prague , Czech Republic
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4
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Tefferi A. Genomics Basics: DNA Structure, Gene Expression, Cloning, Genetic Mapping, and Molecular Tests. Semin Cardiothorac Vasc Anesth 2016; 10:282-90. [PMID: 17200086 DOI: 10.1177/1089253206294343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Genomics is the study of the structure and function of the human genome including genes and their surrounding DNA sequences. The over 3 billion base pairs of the human genome have now been sequenced and approximately 25 000 genes acknowledged. However, only 1% of the entire genome has been assigned to protein coding and decades more work is anticipated to define the functional relevance of noncoding DNA as well as the basis and consequences of sequence variations among individuals. For medical scientists, the focus remains on discovering both disease-causing and disease-susceptibility genes. For pharmaceutical companies, the opportunity to develop molecularly targeted therapy is not going unnoticed. For the practicing physician, the prospect of genomic medicine that incorporates molecular diagnosis and pathogenesis-targeted therapy requires basic understanding of terminology and concepts in molecular biology and the corresponding laboratory tests.
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Affiliation(s)
- Ayalew Tefferi
- Division of Hematology, Mayo Clinic, Rochester, MN 55905, USA.
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5
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Abstract
Nucleoli are formed on the basis of ribosomal genes coding for RNAs of ribosomal particles, but also include a great variety of other DNA regions. In this article, we discuss the characteristics of ribosomal DNA: the structure of the rDNA locus, complex organization and functions of the intergenic spacer, multiplicity of gene copies in one cell, selective silencing of genes and whole gene clusters, relation to components of nucleolar ultrastructure, specific problems associated with replication. We also review current data on the role of non-ribosomal DNA in the organization and function of nucleoli. Finally, we discuss probable causes preventing efficient visualization of DNA in nucleoli.
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6
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Viktorovskaya OV, Schneider DA. Functional divergence of eukaryotic RNA polymerases: unique properties of RNA polymerase I suit its cellular role. Gene 2014; 556:19-26. [PMID: 25445273 DOI: 10.1016/j.gene.2014.10.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/16/2014] [Accepted: 10/17/2014] [Indexed: 02/08/2023]
Abstract
Eukaryotic cells express at least three unique nuclear RNA polymerases. The selective advantage provided by this enhanced complexity is a topic of fundamental interest in cell biology. It has long been known that the gene targets and transcription initiation pathways for RNA polymerases (Pols) I, II and III are distinct; however, recent genetic, biochemical and structural data suggest that even the core enzymes have evolved unique properties. Among the three eukaryotic RNA polymerases, Pol I is considered the most divergent. Transcription of the ribosomal DNA by Pol I is unmatched in its high rate of initiation, complex organization within the nucleolus and functional connection to ribosome assembly. Furthermore, ribosome synthesis is intimately linked to cell growth and proliferation. Thus, there is intense selective pressure on Pol I. This review describes key features of Pol I transcription, discusses catalytic activities of the enzyme and focuses on recent advances in understanding its unique role among eukaryotic RNA polymerases.
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Affiliation(s)
- Olga V Viktorovskaya
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, United States
| | - David A Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, United States.
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7
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Parks AR, Court C, Lubkowska L, Jin DJ, Kashlev M, Court DL. Bacteriophage λ N protein inhibits transcription slippage by Escherichia coli RNA polymerase. Nucleic Acids Res 2014; 42:5823-9. [PMID: 24711367 PMCID: PMC4027172 DOI: 10.1093/nar/gku203] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transcriptional slippage is a class of error in which ribonucleic acid (RNA) polymerase incorporates nucleotides out of register, with respect to the deoxyribonucleic acid (DNA) template. This phenomenon is involved in gene regulation mechanisms and in the development of diverse diseases. The bacteriophage λ N protein reduces transcriptional slippage within actively growing cells and in vitro. N appears to stabilize the RNA/DNA hybrid, particularly at the 5′ end, preventing loss of register between transcript and template. This report provides the first evidence of a protein that directly influences transcriptional slippage, and provides a clue about the molecular mechanism of transcription termination and N-mediated antitermination.
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Affiliation(s)
- Adam R Parks
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Carolyn Court
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Lucyna Lubkowska
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Ding J Jin
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Mikhail Kashlev
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
| | - Donald L Court
- Molecular Control and Genetics Section, Gene Regulation and Chromosome Biology, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
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8
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Németh A, Perez-Fernandez J, Merkl P, Hamperl S, Gerber J, Griesenbeck J, Tschochner H. RNA polymerase I termination: Where is the end? BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:306-17. [PMID: 23092677 DOI: 10.1016/j.bbagrm.2012.10.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/10/2012] [Accepted: 10/17/2012] [Indexed: 01/01/2023]
Abstract
The synthesis of ribosomal RNA (rRNA) precursor molecules by RNA polymerase I (Pol I) terminates with the dissociation of the protein-DNA-RNA ternary complex. Based on in vitro results the mechanism of Pol I termination appeared initially to be rather conserved and simple until this process was more thoroughly re-investigated in vivo. A picture emerged that Pol I termination seems to be connected to co-transcriptional processing, re-initiation of transcription and, possibly, other processes downstream of Pol I transcription units. In this article, our current understanding of the mechanism of Pol I termination and how this process might be implicated in other biological processes in yeast and mammals is summarized and discussed. This article is part of a Special Issue entitled: Transcription by Odd Pols.
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Affiliation(s)
- Attila Németh
- Universität Regensburg, Biochemie-Zentrum Regensburg (BZR), Lehrstuhl Biochemie III, 93053 Regensburg, Germany.
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9
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Franco B, Hernández R, López-Villaseñor I. Trichomonas vaginalis ribosomal RNA: Identification and characterisation of the transcription promoter and terminator sequences. Mol Biochem Parasitol 2012; 185:1-9. [DOI: 10.1016/j.molbiopara.2012.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 04/26/2012] [Accepted: 05/24/2012] [Indexed: 11/16/2022]
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10
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The Reb1-homologue Ydr026c/Nsi1 is required for efficient RNA polymerase I termination in yeast. EMBO J 2012; 31:3480-93. [PMID: 22805593 DOI: 10.1038/emboj.2012.185] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 06/19/2012] [Indexed: 12/27/2022] Open
Abstract
Several DNA cis-elements and trans-acting factors were described to be involved in transcription termination and to release the elongating RNA polymerases from their templates. Different models for the molecular mechanism of transcription termination have been suggested for eukaryotic RNA polymerase I (Pol I) from results of in vitro and in vivo experiments. To analyse the molecular requirements for yeast RNA Pol I termination, an in vivo approach was used in which efficient termination resulted in growth inhibition. This led to the identification of a Myb-like protein, Ydr026c, as bona fide termination factor, now designated Nsi1 (NTS1 silencing protein 1), since it was very recently described as silencing factor of ribosomal DNA. Possible Nsi1 functions in regard to the mechanism of transcription termination are discussed.
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11
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Krzyszton M, Zakrzewska-Placzek M, Koper M, Kufel J. Rat1 and Xrn2: The Diverse Functions of the Nuclear Rat1/Xrn2 Exonuclease. EUKARYOTIC RNASES AND THEIR PARTNERS IN RNA DEGRADATION AND BIOGENESIS, PART A 2012; 31:131-63. [DOI: 10.1016/b978-0-12-404740-2.00007-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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12
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Tate J, Gollnick P. Role of forward translocation in nucleoside triphosphate phosphohydrolase I (NPH I)-mediated transcription termination of vaccinia virus early genes. J Biol Chem 2011; 286:44764-75. [PMID: 22069335 PMCID: PMC3247973 DOI: 10.1074/jbc.m111.263822] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 10/28/2011] [Indexed: 01/04/2023] Open
Abstract
Termination of transcription of vaccinia virus early genes requires the virion form of the viral RNA polymerase (RNAP), a termination signal (UUUUUNU) in the nascent RNA, vaccinia termination factor, nucleoside triphosphate phosphohydrolase I (NPH I), and ATP. NPH I uses ATP hydrolysis to mediate transcript release, and in vitro, ATPase activity requires single-stranded DNA. NPH I shows sequence similarity with the DEXH-box family of proteins, which includes an Escherichia coli ATP-dependent motor protein, Mfd. Mfd releases transcripts and rescues arrested transcription complexes by moving the transcription elongation complex downstream on the DNA template in the absence of transcription elongation. This mechanism is known as forward translocation. In this study, we demonstrate that NPH I also uses forward translocation to catalyze transcript release from viral RNAP. Moreover, we show that NPH I-mediated release can occur at a stalled RNAP in the absence of vaccinia termination factor and U(5)NU when transcription elongation is prevented.
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Affiliation(s)
- Jessica Tate
- From the Department of Biological Sciences, University at Buffalo, Buffalo, New York 14226
| | - Paul Gollnick
- From the Department of Biological Sciences, University at Buffalo, Buffalo, New York 14226
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13
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Transcript Slippage and Recoding. RECODING: EXPANSION OF DECODING RULES ENRICHES GENE EXPRESSION 2010. [DOI: 10.1007/978-0-387-89382-2_19] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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14
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Abreu-Blanco MT, Ramírez JL, Pinto-Santini DM, Papadopoulou B, Guevara P. Analysis of ribosomal RNA transcription termination and 3' end processing in Leishmania amazonensis. Gene 2009; 451:15-22. [PMID: 19914359 DOI: 10.1016/j.gene.2009.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 10/11/2009] [Accepted: 11/03/2009] [Indexed: 11/16/2022]
Abstract
The control of gene expression in the human parasite Leishmania occurs mainly at the post-transcriptional level. Nevertheless, basic cell processes such as ribosome biogenesis seem to be conserved. Mature ribosomal RNAs (rRNAs) are synthesized from typical RNA polymerase I (Pol I) promoters and processed by pathways analogous to other eukaryotes. To further understand Pol I transcription control in these parasites, we have analyzed transcription termination and processing of the rDNA in Leishmania amazonensis. 3'-end S1 mapping of rRNA precursors identified three termini, one corresponding to the mature 28S rRNA and two to the rDNA intergenic spacer (IGS), termed T1 and T2, for precursors which are 185 and 576 nucleotides longer, respectively. Both T1 and T2 are associated with conserved G + C rich elements that have the potential to form hairpin structures and T-rich clusters. We found that two fragments of 423 bp and 233 bp, flanking sites T1 and T2 respectively when placed upstream of the green fluorescent protein gene (GFP), negatively affected the Pol I-driven transcription of this gene, which suggests the presence of a transcription terminator element in these regions. Deletion analysis pointed to a CCCTTTT heptamer as part of the putative terminator and suggested that the hairpins are processing signals.
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Affiliation(s)
- María Teresa Abreu-Blanco
- Laboratorio de Genética Molecular. Instituto de Biología Experimental. Universidad Central de Venezuela. Apartado Postal 48162. Caracas 1041A. Venezuela
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15
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Dengl S, Cramer P. Torpedo nuclease Rat1 is insufficient to terminate RNA polymerase II in vitro. J Biol Chem 2009; 284:21270-9. [PMID: 19535338 PMCID: PMC2755851 DOI: 10.1074/jbc.m109.013847] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 04/28/2009] [Indexed: 11/06/2022] Open
Abstract
Termination of RNA polymerase (pol) II transcription in vivo requires the 5'-RNA exonuclease Rat1. It was proposed that Rat1 degrades RNA from the 5'-end that is created by transcript cleavage, catches up with elongating pol II, and acts like a Torpedo that removes pol II from DNA. Here we test the Torpedo model in an in vitro system based on bead-coupled pol II elongation complexes (ECs). Recombinant Rat1 complexes with Rai1, and with Rai1 and Rtt103, degrade RNA extending from the EC until they reach the polymerase surface but fail to terminate pol II. Instead, the EC retains an approximately 18-nucleotide RNA that remains with its 3'-end at the active site and can be elongated. Thus, pol II termination apparently requires a factor or several factors in addition to Rat1, Rai1, and Rtt103, post-translational modifications of these factors, or unusual reaction conditions.
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Affiliation(s)
- Stefan Dengl
- From the Gene Center and Center for Integrated Protein Science Munich, Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Patrick Cramer
- From the Gene Center and Center for Integrated Protein Science Munich, Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
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16
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Zúñiga S, Sola I, Cruz JLG, Enjuanes L. Role of RNA chaperones in virus replication. Virus Res 2008; 139:253-66. [PMID: 18675859 PMCID: PMC7114511 DOI: 10.1016/j.virusres.2008.06.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 06/18/2008] [Accepted: 06/23/2008] [Indexed: 01/06/2023]
Abstract
RNA molecules are functionally diverse in part due to their extreme structural flexibility that allows rapid regulation by refolding. RNA folding could be a difficult process as often molecules adopt a spatial conformation that is very stable but not biologically functional, named a kinetic trap. RNA chaperones are non-specific RNA binding proteins that help RNA folding by resolving misfolded structures or preventing their formation. There is a large number of viruses whose genome is RNA that allows some evolutionary advantages, such as rapid genome mutation. On the other hand, regions of the viral RNA genomes can adopt different structural conformations, some of them lacking functional relevance and acting as misfolded intermediates. In fact, for an efficient replication, they often require RNA chaperone activities. There is a growing list of RNA chaperones encoded by viruses involved in different steps of the viral cycle. Also, cellular RNA chaperones have been involved in replication of RNA viruses. This review briefly describes RNA chaperone activities and is focused in the roles that viral or cellular nucleic acid chaperones have in RNA virus replication, particularly in those viruses that require discontinuous RNA synthesis.
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Affiliation(s)
- Sonia Zúñiga
- Centro Nacional de Biotecnología, CSIC, Department of Molecular and Cell Biology, Campus Universitario de Cantoblanco, Darwin 3, 28049 Madrid, Spain
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17
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El Hage A, Koper M, Kufel J, Tollervey D. Efficient termination of transcription by RNA polymerase I requires the 5' exonuclease Rat1 in yeast. Genes Dev 2008; 22:1069-81. [PMID: 18413717 DOI: 10.1101/gad.463708] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
During transcription termination by RNA polymerase II on protein-coding genes, the nuclear 5' exonuclease Rat1/Xrn2 degrades the nascent transcript downstream from the polyadenylation site and "torpedoes" the polymerase. We report that the activity of Rat1 is also required for efficient termination by RNA polymerase I (Pol I) on the rDNA. In strains lacking catalytically active Rat1 or its cofactor Rai1, Pol I reads through the major, "Reb1-dependent" terminator (T1) but stops downstream at the "fail-safe" terminator (T2) and replication fork barrier (RFB). The absence of both Rat1 and the RFB-binding protein Fob1 increased Pol I read-through of T2 and the RFB. We propose that cotranscriptional cleavage of the pre-rRNA by the endonuclease Rnt1 generates a loading site for the Rat1/Rai1 complex, which then degrades the nascent transcript. When Rat1 catches Pol I, which is predicted to be paused at T1, transcription is terminated.
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Affiliation(s)
- Aziz El Hage
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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18
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Nabavi S, Nazar RN. Nonpolyadenylated RNA polymerase II termination is induced by transcript cleavage. J Biol Chem 2008; 283:13601-10. [PMID: 18321857 DOI: 10.1074/jbc.m710125200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the termination of transcription and 3' RNA processing of the eukaryotic mRNA has been linked to a polyadenylation signal and a transcript cleavage process, much less is known about the termination or processing of nonpolyadenylated RNA polymerase II transcripts. An efficiently expressed plasmid-based expression system was used to study the termination and processing of Schizosaccharomyces pombe U3 small nucleolar RNA (snoRNA) transcripts in vivo. The termination assay was linked to cell transformation, and restriction fragment length polymorphism was used to determine levels of plasmid-derived U3 snoRNA. Mutation analyses in vivo indicate that the maturation of the 3' end is not directly dependent on an external cis-acting sequence or structure; rather, it is dependent on a transcript cleavage that can occur hundreds or even thousands of nucleotides downstream of the mature U3 snoRNA sequence. Similarly, termination is dependent on the same transcript cleavage that is localized in a hairpin structure that normally follows the 3' end of the U3 snoRNA but that also can be moved hundreds or thousands of nucleotides downstream. Both processes, however, can be induced simultaneously and equally efficiently with a single unrelated Pac1 endonuclease-labile structure. The results support a "reversed torpedoes" model in which a single cleavage allows exonucleases and/or other protein factors access to the transcript leading to transcription termination in one direction and RNA maturation in the other direction.
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Affiliation(s)
- Sadeq Nabavi
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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19
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Ibrahim H, Wilusz J, Wilusz CJ. RNA recognition by 3'-to-5' exonucleases: the substrate perspective. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2007; 1779:256-65. [PMID: 18078842 DOI: 10.1016/j.bbagrm.2007.11.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 12/30/2022]
Abstract
The 3'-to-5' exonucleolytic decay and processing of a variety of RNAs is an essential feature of RNA metabolism in all cells. The 3'-5' exonucleases, and in particular the exosome, are involved in a large number of pathways from 3' processing of rRNA, snRNA and snoRNA, to decay of mRNAs and mRNA surveillance. The potent enzymes performing these reactions are regulated to prevent processing of inappropriate substrates whilst mature RNA molecules exhibit several attributes that enable them to evade 3'-5' attack. How does an enzyme perform such selective activities on different substrates? The goal of this review is to provide an overview and perspective of available data on the underlying principles for the recognition of RNA substrates by 3'-to-5' exonucleases.
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Affiliation(s)
- Hend Ibrahim
- Colorado State University, Department of Microbiology, Immunology and Pathology, Fort Collins, CO 80525, USA
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20
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Conconi A. The yeast rDNA locus: a model system to study DNA repair in chromatin. DNA Repair (Amst) 2007; 4:897-908. [PMID: 15996904 DOI: 10.1016/j.dnarep.2005.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2005] [Indexed: 11/23/2022]
Abstract
Most of the studies on the effect of chromatin structure and chromatin remodeling on DNA repair are based on in vitro reconstituted assays. In such experiments individual nucleosomes are either released by nuclease digestion of native chromatin fibers or are assembled from purified histones. Though reconstituted assays are valid approaches to follow NER in chromatin they are of somehow limited physiological relevance since single core particles do not exist in vivo [K. van Holde, J. Zlatanova, The nucleosome core particle: does it have structural and physiological relevance? Bioessays 21 (1999) 776-778]. This is particularly true for studies involving core histones tails, as in their natural chromatin context histones tails participate in interactions that are not necessarily present in vitro [J.C. Hansen, C. Tse, A.P. Wolffe, Structure and function of the core histone N-termini: more than meets the eye, Biochemistry 37 (1998) 17637-17641; J.J. Hayes, J.C. Hansen, Nucleosomes and chromatin fiber, Curr. Opin. Genet. Dev. 11 (2001) 124-129]. Indeed it was found that human DNA ligase I has the capability to ligate a nick on the surface of a 215bp nucleosome but not a nick in a nucleosome lacking linker DNA, possibly because of forced interactions between histone tails and core DNA present in the latter complex [D.R. Chafin, J.M. Vitolo, L.A. Henricksen, B.A. Bambara, J.J. Hayes, Human DNA ligase I efficiently seals nicks in nucleosomes, EMBO J. 19 (2000) 5492-5501]. In addition, chromatin remodeling could also occur in the higher ordered folding of chromatin and involve multiple arrays of nucleosomes [P.J. Horn, C.L. Peterson, Chromatin higher order folding: wrapping up transcription, Science 297 (2002) 1824-1827]. By studying the chromatin structure of ribosomal genes in yeast, our knowledge of the fate of nucleosomes during transcription and DNA replication has improved considerably [R. Lucchini, J.M. Sogo, The dynamic structure of ribosomal RNA gene chromatin, in: M.R. Paule (Ed.), Transcription of Ribosomal RNA Genes by Eukaryotic RNA Polymerase I, Springer-Verlag/R.G. Landes Company, 1998, pp. 254-276]. How nuclear processes such as DNA repair take place in chromatin is still largely unknown, and in this review I discuss how the yeast rDNA locus may be exploited to investigate DNA repair and chromatin modification in vivo.
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Affiliation(s)
- Antonio Conconi
- Department de Microbiologie et Infectiologie, Faculte de Medecine, Universite de Sherbrooke, 3001, 12(e) Avenue Nord, Sherbrooke, Que., Canada J1H 5N4
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21
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Shibata R, Bessho Y, Shinkai A, Nishimoto M, Fusatomi E, Terada T, Shirouzu M, Yokoyama S. Crystal structure and RNA-binding analysis of the archaeal transcription factor NusA. Biochem Biophys Res Commun 2007; 355:122-8. [PMID: 17288993 DOI: 10.1016/j.bbrc.2007.01.119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 01/23/2007] [Indexed: 11/29/2022]
Abstract
The transcription factor NusA functions in transcriptional regulation involving termination in bacteria. A NusA homolog consisting of only the two KH domains is widely conserved in archaea, but its function remains unknown. We have found that Aeropyrum pernix NusA strongly binds to a certain CU-rich sequence near a termination signal. Our crystal structure of A. pernix NusA revealed that its spatial arrangement is quite similar to that of the KH domains of bacterial NusA. Thus, we consider archaeal NusA to have retained some functions of bacterial NusA, including the ssRNA-binding ability. Remarkable structural differences between archaeal and bacterial NusA exist at the interface with RNAP, in connection with the different NusA-binding sites around the termination signals. Transcriptional termination in archaea could differ from all of the known bacterial and eukaryal mechanisms, in terms of the combination of a bacterial factor and a eukaryal-type RNAP.
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Affiliation(s)
- Rie Shibata
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
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22
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Pasternak AO, Spaan WJM, Snijder EJ. Nidovirus transcription: how to make sense...? J Gen Virol 2006; 87:1403-1421. [PMID: 16690906 DOI: 10.1099/vir.0.81611-0] [Citation(s) in RCA: 255] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Many positive-stranded RNA viruses use subgenomic mRNAs to express part of their genetic information. To produce structural and accessory proteins, members of the order Nidovirales (corona-, toro-, arteri- and roniviruses) generate a 3' co-terminal nested set of at least three and often seven to nine mRNAs. Coronavirus and arterivirus subgenomic transcripts are not only 3' co-terminal but also contain a common 5' leader sequence, which is derived from the genomic 5' end. Their synthesis involves a process of discontinuous RNA synthesis that resembles similarity-assisted RNA recombination. Most models proposed over the past 25 years assume co-transcriptional fusion of subgenomic RNA leader and body sequences, but there has been controversy over the question of whether this occurs during plus- or minus-strand synthesis. In the latter model, which has now gained considerable support, subgenomic mRNA synthesis takes place from a complementary set of subgenome-size minus-strand RNAs, produced by discontinuous minus-strand synthesis. Sense-antisense base-pairing interactions between short conserved sequences play a key regulatory role in this process. In view of the presumed common ancestry of nidoviruses, the recent finding that ronivirus and torovirus mRNAs do not contain a common 5' leader sequence is surprising. Apparently, major mechanistic differences must exist between nidoviruses, which raises questions about the functions of the common leader sequence and nidovirus transcriptase proteins and the evolution of nidovirus transcription. In this review, nidovirus transcription mechanisms are compared, the experimental systems used are critically assessed and, in particular, the impact of recently developed reverse genetic systems is discussed.
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Affiliation(s)
- Alexander O Pasternak
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, LUMC P4-26, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Willy J M Spaan
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, LUMC P4-26, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, LUMC P4-26, PO Box 9600, 2300 RC Leiden, The Netherlands
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23
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Trinh V, Langelier MF, Archambault J, Coulombe B. Structural perspective on mutations affecting the function of multisubunit RNA polymerases. Microbiol Mol Biol Rev 2006; 70:12-36. [PMID: 16524917 PMCID: PMC1393249 DOI: 10.1128/mmbr.70.1.12-36.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
High-resolution crystallographic structures of multisubunit RNA polymerases (RNAPs) have increased our understanding of transcriptional mechanisms. Based on a thorough review of the literature, we have compiled the mutations affecting the function of multisubunit RNA polymerases, many of which having been generated and studied prior to the publication of the first high-resolution structure, and highlighted the positions of the altered amino acids in the structures of both the prokaryotic and eukaryotic enzymes. The observations support many previous hypotheses on the transcriptional process, including the implication of the bridge helix and the trigger loop in the processivity of RNAP, the importance of contacts between the RNAP jaw-lobe module and the downstream DNA in the establishment of a transcription bubble and selection of the transcription start site, the destabilizing effects of ppGpp on the open promoter complex, and the link between RNAP processivity and termination. This study also revealed novel, remarkable features of the RNA polymerase catalytic mechanisms that will require additional investigation, including the putative roles of fork loop 2 in the establishment of a transcription bubble, the trigger loop in start site selection, and the uncharacterized funnel domain in RNAP processivity.
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Affiliation(s)
- Vincent Trinh
- Gene Transcription Laboratory, Institut de Recherches Cliniques de Montréal, 110 Ave. des Pins Ouest, Montréal, Québec, Canada
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24
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Guffanti E, Corradini R, Ottonello S, Dieci G. Functional dissection of RNA polymerase III termination using a peptide nucleic acid as a transcriptional roadblock. J Biol Chem 2004; 279:20708-16. [PMID: 14970213 DOI: 10.1074/jbc.m311295200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that a T(10) peptide nucleic acid (PNA) bound to the transcriptional terminator of a Saccharomyces cerevisiae tDNA(Ile)(TAT) gene arrests elongating yeast RNA polymerase (pol) III at a position that precedes by 20 bp the upstream end of the PNA roadblock (Dieci, G., Corradini, R., Sforza, S., Marchelli, R., and Ottonello, S. (2001) J. Biol. Chem. 276, 5720-5725). Here, a PNA-binding cassette was placed at various distances downstream of a functional tDNA(Ile) transcriptional terminator (T(6)) that is not bound by the T(10) PNA, and the effect of the PNA roadblock on RNA 3'-end formation, transcript release, and transcription reinitiation was examined. With a PNA roadblock placed as close as 5 bp downstream of the T(6) terminator, pol III could still reach the termination site and complete pre-tRNA synthesis, implying that the catalytic site-to-front edge (C-F) distance of the polymerase can shorten by >10 bp upon recognition of the terminator element. In addition, transcripts synthesized by a PNA-roadblocked terminating pol III were found to be released from transcription complexes. Interestingly, however, the same roadblock dramatically reduced the rate of transcription reinitiation. Also, when placed 5 bp downstream of a mutationally inactivated terminator element (T(3)GT(2)), the PNA roadblock restored transcription termination, thus indicating that the inactivated terminator is compromised in its ability to cause pol III pausing, but can still induce C-F distance shortening and transcript release. The latter two activities were found to be further impaired in variants of the inactivated terminator bearing fewer than three consecutive T residues (T(2)G(2)T(2) and TG(2)TGT). The data indicate that RNA polymerase pausing, C-F distance shortening, and transcript release are functionally distinguishable features of the termination process and point to the RNA release propensity of pol III as a major determinant of its remarkably high termination efficiency.
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Affiliation(s)
- Elisa Guffanti
- Dipartimento di Biochimica e Biologia Molecolare and Dipartimento di Chimica Organica e Industriale, Università degli Studi di Parma, 43100 Parma, Italy
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25
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Barak O, Lazzaro MA, Lane WS, Speicher DW, Picketts DJ, Shiekhattar R. Isolation of human NURF: a regulator of Engrailed gene expression. EMBO J 2004; 22:6089-100. [PMID: 14609955 PMCID: PMC275440 DOI: 10.1093/emboj/cdg582] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The modification of chromatin structure is an important regulatory mechanism for developmental gene expression. Differential expression of the mammalian ISWI genes, SNF2H and SNF2L, has suggested that they possess distinct developmental roles. Here we describe the purification and characterization of the first human SNF2L-containing complex. The subunit composition suggests that it represents the human ortholog of the Drosophila nucleosome-remodeling factor (NURF) complex. Human NURF (hNURF) is enriched in brain, and we demonstrate that it regulates human Engrailed, a homeodomain protein that regulates neuronal development in the mid-hindbrain. Furthermore, we show that hNURF potentiates neurite outgrowth in cell culture. Taken together, our data suggess a role for an ISWI complex in neuronal growth.
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Affiliation(s)
- Orr Barak
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
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26
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Abstract
Long recognized as a target of regulation in prokaryotes, transcript elongation has recently become the focus of many investigators interested in eukaryotic gene expression. The growth of this area has been fueled by the availability of new methods and molecular structures, expanding sequence databases and an appreciation for the exquisite coordination required among different processes in the nucleus. Our article collates new information on regulatory accessory factors, as well as their ultimate target, RNA polymerase, in the nucleus of eukaryotic cells. How this regulation influences the biology of the organism is quite profound, and from single cell to multicellular eukaryotes significant similarities exist in the molecular responses to extracellular signals during transcript elongation. The most advanced genetic knowledge in this area comes from Saccharomyces cerevisiae, but the biochemistry and cell biology results from other organisms are also highlighted.
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Affiliation(s)
- Karen M Arndt
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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27
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Cheutin T, O'Donohue MF, Beorchia A, Vandelaer M, Kaplan H, Deféver B, Ploton D, Thiry M. Three-dimensional organization of active rRNA genes within the nucleolus. J Cell Sci 2002; 115:3297-307. [PMID: 12140261 DOI: 10.1242/jcs.115.16.3297] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In this work, we have localized transcribing rRNA genes at the ultrastructural level and described their three-dimensional organization within the nucleolus by electron tomography. Isolated nucleoli, which exhibit a reduced transcriptional rate, were used to determine the sites of initial BrUTP incorporation (i.e. rRNA synthesis by the transcriptional machinery). Using pulse-chase experiments with BrUTP and an elongation inhibitor,cordycepin, it was possible to precisely localize the initial sites of BrUTP incorporation. Our data show that BrUTP incorporation initially takes place in the fibrillar centers and that elongating rRNAs rapidly enter the surrounding dense fibrillar component. Furthermore, we investigated the spatial arrangement of RNA polymerase I molecules within the whole volume of the fibrillar centers. Electron tomography was performed on thick sections of cells that had been labeled with anti-RNA polymerase I antibodies prior to embedding. Detailed tomographic analyses revealed that RNA polymerase I molecules are mainly localized within discrete clusters. In each of them, RNA polymerase I molecules were grouped as several coils, 60 nm in diameter. Overall, these findings have allowed us to propose a model for the three-dimensional organization of transcribing rDNA genes within the nucleolus.
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Affiliation(s)
- Thierry Cheutin
- Unité MéDIAN, CNRS UMR 6142, UFR de Pharmacie, 51 rue Cognacq-Jay, 51096 Reims Cedex, France
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28
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Tefferi A, Wieben ED, Dewald GW, Whiteman DAH, Bernard ME, Spelsberg TC. Primer on medical genomics part II: Background principles and methods in molecular genetics. Mayo Clin Proc 2002; 77:785-808. [PMID: 12173714 DOI: 10.4065/77.8.785] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The nucleus of every human cell contains the full complement of the human genome, which consists of approximately 30,000 to 70,000 named and unnamed genes and many intergenic DNA sequences. The double-helical DNA molecule in a human cell, associated with special proteins, is highly compacted into 22 pairs of autosomal chromosomes and an additional pair of sex chromosomes. The entire cellular DNA consists of approximately 3 billion base pairs, of which only 1% is thought to encode a functional protein or a polypeptide. Genetic information is expressed and regulated through a complex system of DNA transcription, RNA processing, RNA translation, and posttranslational and cotranslational modification of proteins. Advances in molecular biology techniques have allowed accurate and rapid characterization of DNA sequences as well as identification and quantification of cellular RNA and protein. Global analytic methods and human genetic mapping are expected to accelerate the process of identification and localization of disease genes. In this second part of an educational series in medical genomics, selected principles and methods in molecular biology are recapped, with the intent to prepare the reader for forthcoming articles with a more direct focus on aspects of the subject matter.
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Affiliation(s)
- Ayalew Tefferi
- Division of Hematology and Internal Medicine, Mayo Clinic, Rochester, Minn 55905, USA
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29
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Pasternak AO, van den Born E, Spaan WJ, Snijder EJ. Sequence requirements for RNA strand transfer during nidovirus discontinuous subgenomic RNA synthesis. EMBO J 2001; 20:7220-8. [PMID: 11742998 PMCID: PMC125340 DOI: 10.1093/emboj/20.24.7220] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2001] [Revised: 10/25/2001] [Accepted: 11/01/2001] [Indexed: 12/02/2022] Open
Abstract
Nidovirus subgenomic mRNAs contain a leader sequence derived from the 5' end of the genome fused to different sequences ('bodies') derived from the 3' end. Their generation involves a unique mechanism of discontinuous subgenomic RNA synthesis that resembles copy-choice RNA recombination. During this process, the nascent RNA strand is transferred from one site in the template to another, during either plus or minus strand synthesis, to yield subgenomic RNA molecules. Central to this process are transcription-regulating sequences (TRSs), which are present at both template sites and ensure the fidelity of strand transfer. Here we present results of a comprehensive co-variation mutagenesis study of equine arteritis virus TRSs, demonstrating that discontinuous RNA synthesis depends not only on base pairing between sense leader TRS and antisense body TRS, but also on the primary sequence of the body TRS. While the leader TRS merely plays a targeting role for strand transfer, the body TRS fulfils multiple functions. The sequences of mRNA leader-body junctions of TRS mutants strongly suggested that the discontinuous step occurs during minus strand synthesis.
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Affiliation(s)
| | | | | | - Eric J. Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
Corresponding author e-mail: A.O.Pasternak and E.van den Born contributed equally to this work
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30
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De Backer MD, Nelissen B, Logghe M, Viaene J, Loonen I, Vandoninck S, de Hoogt R, Dewaele S, Simons FA, Verhasselt P, Vanhoof G, Contreras R, Luyten WH. An antisense-based functional genomics approach for identification of genes critical for growth of Candida albicans. Nat Biotechnol 2001; 19:235-41. [PMID: 11231556 DOI: 10.1038/85677] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Converting the complete genome sequence of Candida albicans into meaningful biological information will require comprehensive screens for identifying functional classes of genes. Most systems described so far are not applicable to C. albicans because of its difficulty with mating, its diploid nature, and the lack of functional random insertional mutagenesis methods. We examined artificial gene suppression as a means to identify gene products critical for growth of this pathogen; these represent new antifungal drug targets. To achieve gene suppression we combined antisense RNA inhibition and promoter interference. After cloning antisense complementary DNA (cDNA) fragments under control of an inducible GAL1 promoter, we transferred the resulting libraries to C. albicans. Over 2,000 transformant colonies were screened for a promoter-induced diminished-growth phenotype. After recovery of the plasmids, sequence determination of their inserts revealed the messenger RNA (mRNA) they inhibited or the gene they disrupted. Eighty-six genes critical for growth were identified, 45 with unknown function. When used in high-throughput screening for antifungals, the crippled C. albicans strains generated in this study showed enhanced sensitivity to specific drugs.
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MESH Headings
- Antifungal Agents/pharmacology
- Candida albicans/drug effects
- Candida albicans/genetics
- Candida albicans/growth & development
- Cloning, Molecular/methods
- DNA, Antisense/genetics
- Drug Evaluation, Preclinical
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Gene Expression Regulation, Fungal
- Gene Library
- Genes, Essential/genetics
- Genes, Fungal/genetics
- Genome, Fungal
- Genomics/methods
- Heterozygote
- Microbial Sensitivity Tests
- Mutagenesis, Insertional/genetics
- Phenotype
- Promoter Regions, Genetic/genetics
- RNA, Antisense/genetics
- RNA, Fungal/analysis
- RNA, Fungal/genetics
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Transformation, Genetic
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Affiliation(s)
- M D De Backer
- Department of Advanced Bio-Technologies, Janssen Pharmaceutica, Turnhoutseweg 30, B2340 Beerse, Belgium.
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31
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The Transcription of Genes. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50031-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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32
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Wang Z, Bai L, Hsieh YJ, Roeder RG. Nuclear factor 1 (NF1) affects accurate termination and multiple-round transcription by human RNA polymerase III. EMBO J 2000; 19:6823-32. [PMID: 11118217 PMCID: PMC305894 DOI: 10.1093/emboj/19.24.6823] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We have shown previously that the TFIIIC1/TFIIIC1' fraction interacts specifically with the VA1 terminator regions to affect both termination and initiation/reinitiation of transcription by human RNA polymerase III. Here, we further purified the VA1 terminator-binding factor to apparent homogeneity and found, by peptide sequence analysis, that it belongs to the NF1 protein family. NF1 interacts specifically with the NF1-binding sites within the terminator regions of the VA1 gene and with two subunits (TFIIIC220 and TFIIIC110) of human TFIIIC2. Immunodepletion with anti-NF1 antibodies dramatically decreases transcription from the VA1 template in nuclear extract, and mutation at the NF1-binding site in the terminator region of the VA1 gene selectively affects multiple-round transcription (reinitiation of transcription) and termination. In addition, NF1 acts in conjunction with TFIIIC to promote accurate termination by RNA polymerase III on a C-tailed VA1 template.
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Affiliation(s)
- Z Wang
- The Laboratory of Biochemistry and Molecular Biology,The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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33
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Schnare MN, Collings JC, Spencer DF, Gray MW. The 28S-18S rDNA intergenic spacer from Crithidia fasciculata: repeated sequences, length heterogeneity, putative processing sites and potential interactions between U3 small nucleolar RNA and the ribosomal RNA precursor. Nucleic Acids Res 2000; 28:3452-61. [PMID: 10982863 PMCID: PMC110749 DOI: 10.1093/nar/28.18.3452] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2000] [Revised: 07/17/2000] [Accepted: 07/28/2000] [Indexed: 11/12/2022] Open
Abstract
In Crithidia fasciculata, the ribosomal RNA (rRNA) gene repeats range in size from approximately 11 to 12 kb. This length heterogeneity is localized to a region of the intergenic spacer (IGS) that contains tandemly repeated copies of a 19mer sequence. The IGS also contains four copies of an approximately 55 nt repeat that has an internal inverted repeat and is also present in the IGS of Leishmania species. We have mapped the C.fasciculata transcription initiation site as well as two other reverse transcriptase stop sites that may be analogous to the A0 and A' pre-rRNA processing sites within the 5' external transcribed spacer (ETS) of other eukaryotes. Features that could influence processing at these sites include two stretches of conserved primary sequence and three secondary structure elements present in the 5' ETS. We also characterized the C.fasciculata U3 snoRNA, which has the potential for base-pairing with pre-rRNA sequences. Finally, we demonstrate that biosynthesis of large subunit rRNA in both C. fasciculata and Trypanosoma brucei involves 3'-terminal addition of three A residues that are not present in the corresponding DNA sequences.
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MESH Headings
- Animals
- Base Pairing
- Base Sequence
- Conserved Sequence
- Crithidia fasciculata/genetics
- Crithidia fasciculata/metabolism
- DNA, Protozoan/genetics
- DNA, Protozoan/metabolism
- DNA, Ribosomal/genetics
- DNA, Ribosomal/metabolism
- Genetic Heterogeneity
- Molecular Sequence Data
- Nucleic Acid Conformation
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal/metabolism
- RNA, Small Nucleolar/chemistry
- RNA, Small Nucleolar/genetics
- RNA, Small Nucleolar/metabolism
- Repetitive Sequences, Nucleic Acid
- Restriction Mapping
- Sequence Alignment
- Sequence Analysis, DNA
- Trypanosoma brucei brucei/genetics
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Affiliation(s)
- M N Schnare
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada
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34
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Greger IH, Aranda A, Proudfoot N. Balancing transcriptional interference and initiation on the GAL7 promoter of Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2000; 97:8415-20. [PMID: 10890898 PMCID: PMC26962 DOI: 10.1073/pnas.140217697] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transcriptional termination of the GAL10 gene in Saccharomyces cerevisiae depends on the efficiency of polyadenylation. Either cis mutations in the poly(A) signal or trans mutations of mRNA 3' end cleavage factors result in GAL10 read-through transcripts into the adjacent GAL7 gene and inactivation (occlusion) of the GAL7 promoter. Herein, we present a molecular explanation of this transcriptional interference phenomenon. In vivo footprinting data reveal that GAL7 promoter occlusion is associated with the displacement of Gal4p transcription factors from the promoter. Interestingly, overexpression of Gal4p restores promoter occupancy, activates GAL7 expression, and rescues growth on the otherwise toxic galactose substrate. Our data therefore demonstrate a precise balance between transcriptional interference and initiation.
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Affiliation(s)
- I H Greger
- Sir William Dunn School of Pathology, South Parks Road, University of Oxford, Oxford OX1 3RE, United Kingdom
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35
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Abstract
The task of transcribing nuclear genes is shared between three RNA polymerases in eukaryotes: RNA polymerase (pol) I synthesizes the large rRNA, pol II synthesizes mRNA and pol III synthesizes tRNA and 5S rRNA. Although pol II has received most attention, pol I and pol III are together responsible for the bulk of transcriptional activity. This survey will summarise what is known about the process of transcription by pol I and pol III, how it happens and the proteins involved. Attention will be drawn to the similarities between the three nuclear RNA polymerase systems and also to their differences.
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Affiliation(s)
- M R Paule
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
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36
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Reeder RH, Guevara P, Roan JG. Saccharomyces cerevisiae RNA polymerase I terminates transcription at the Reb1 terminator in vivo. Mol Cell Biol 1999; 19:7369-76. [PMID: 10523625 PMCID: PMC84730 DOI: 10.1128/mcb.19.11.7369] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have mapped transcription termination sites for RNA polymerase I in the yeast Saccharomyces cerevisiae. S1 nuclease mapping shows that the primary terminator is the Reb1p terminator located at +93 downstream of the 3' end of 25S rRNA. Reverse transcription coupled with quantitative PCR shows that approximately 90% of all transcripts terminate at this site. Transcripts which read through the +93 site quantitatively terminate at a fail-safe terminator located further downstream at +250. Inactivation of Rnt1p (an RNase III involved in processing the 3' end of 25S rRNA) greatly stabilizes transcripts extending to both sites and increases readthrough at the +93 site. In vivo assay of mutants of the Reb1p terminator shows that this site operates in vivo by the same mechanism as has previously been delineated through in vitro studies.
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Affiliation(s)
- R H Reeder
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
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37
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Zhao J, Hyman L, Moore C. Formation of mRNA 3' ends in eukaryotes: mechanism, regulation, and interrelationships with other steps in mRNA synthesis. Microbiol Mol Biol Rev 1999; 63:405-45. [PMID: 10357856 PMCID: PMC98971 DOI: 10.1128/mmbr.63.2.405-445.1999] [Citation(s) in RCA: 808] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Formation of mRNA 3' ends in eukaryotes requires the interaction of transacting factors with cis-acting signal elements on the RNA precursor by two distinct mechanisms, one for the cleavage of most replication-dependent histone transcripts and the other for cleavage and polyadenylation of the majority of eukaryotic mRNAs. Most of the basic factors have now been identified, as well as some of the key protein-protein and RNA-protein interactions. This processing can be regulated by changing the levels or activity of basic factors or by using activators and repressors, many of which are components of the splicing machinery. These regulatory mechanisms act during differentiation, progression through the cell cycle, or viral infections. Recent findings suggest that the association of cleavage/polyadenylation factors with the transcriptional complex via the carboxyl-terminal domain of the RNA polymerase II (Pol II) large subunit is the means by which the cell restricts polyadenylation to Pol II transcripts. The processing of 3' ends is also important for transcription termination downstream of cleavage sites and for assembly of an export-competent mRNA. The progress of the last few years points to a remarkable coordination and cooperativity in the steps leading to the appearance of translatable mRNA in the cytoplasm.
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Affiliation(s)
- J Zhao
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, Massachusetts 02111, USA
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38
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Affiliation(s)
- B Ganter
- Department of Pathology, Stanford University School of Medicine, California 94305, USA
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39
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Abstract
Gene expression is modulated by regulatory elements that influence transcription elongation by RNA polymerase: terminators that disrupt the elongation complex and release RNA, and regulators that overcome termination signals. RNA release from Escherichia coli RNA polymerase can be induced by a complementary oligonucleotide that replaces the upstream half of the RNA hairpin stem of intrinsic terminator transcripts, implying that RNA hairpins act by extracting RNA from the transcription complex. A transcription antiterminator inhibits this activity of oligonucleotides and therefore protects the elongation complex from destabilizing attacks on the emerging transcript. These effects illuminate the structure of the complex and the mechanism of transcription termination.
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MESH Headings
- Base Pairing
- Base Sequence
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA-Directed RNA Polymerases/genetics
- DNA-Directed RNA Polymerases/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Models, Genetic
- Molecular Sequence Data
- Nucleic Acid Conformation
- Oligodeoxyribonucleotides/chemistry
- Oligodeoxyribonucleotides/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Templates, Genetic
- Terminator Regions, Genetic
- Transcription, Genetic
- Viral Proteins/metabolism
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Affiliation(s)
- W S Yarnell
- Section of Biochemistry, Molecular and Cell Biology, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA
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40
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Reeder RH. Regulation of RNA polymerase I transcription in yeast and vertebrates. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1999; 62:293-327. [PMID: 9932458 DOI: 10.1016/s0079-6603(08)60511-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
This article focuses on what is currently known about the regulation of transcription by RNA polymerase I (pol I) in eukaryotic organisms at opposite ends of the evolutionary spectrum--a yeast, Saccharomyces cerevisiae, and vertebrates, including mice, frogs, and man. Contemporary studies that have defined the DNA sequence elements are described, as well as the majority of the basal transcription factors essential for pol I transcription. Situations in which pol I transcription is known to be regulated are reviewed and possible regulatory mechanisms are critically discussed. Some aspects of basal pol I transcription machinery appear to have been conserved from fungi to vertebrates, but other aspects have evolved, perhaps to meet the needs of a metazoan organism. Different parts of the pol I transcription machinery are regulatory targets depending on different physiological stimuli. This suggests that multiple signaling pathways may also be involved. The involvement of ribosomal genes and their transcripts in events such as mitosis, cancer, and aging is discussed.
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Affiliation(s)
- R H Reeder
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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41
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Abstract
Downstream elements (DSEs) with transcriptional pausing activity play an important role in transcription termination of RNA polymerase II. We have defined two such DSEs in Schizosaccharomyces pombe, one for the ura4 gene and a new one in the 3'-end region of the nmt2 gene. Although these DSEs do not have sequence homology, both are orientation specific and are composed of multiple and redundant sequence elements that work together to achieve full pausing activity. Previous studies on the nmt1 and nmt2 genes revealed that transcription extends several kilobases past the genes' poly(A) sites. We show that the insertion of either DSE immediately downstream of the nmt1 poly(A) site induces more immediate termination. nmt2 termination efficiency can be increased by moving the DSE closer to the poly(A) site. These results suggest that DSEs may be a common feature in yeast genes.
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Affiliation(s)
- A Aranda
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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42
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Liu M, Xie Z, Price DH. A human RNA polymerase II transcription termination factor is a SWI2/SNF2 family member. J Biol Chem 1998; 273:25541-4. [PMID: 9748214 DOI: 10.1074/jbc.273.40.25541] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We obtained protein sequence information from Drosophila factor 2, an ATP-dependent RNA polymerase II transcription termination factor, and discovered that it was identical to a SWI2/SNF2 family member called lodestar. Portions of putative human and Caenorhabditis elegans homologues were found in the sequence data bases and a complete cDNA for the human factor was generated using polymerase chain reaction techniques. Recombinant human factor 2 was produced in a baculovirus expression system, purified, and characterized. Similar to the authentic Drosophila factor, the human factor displayed a strong double-stranded DNA-dependent ATPase activity that was inhibited by single-stranded DNA and exhibited RNA polymerase II termination activity. Both factors were able to work on elongation complexes from either species. We discuss the mechanism of termination by factor 2 and the implications for the role of factor 2 in cellular activities.
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Affiliation(s)
- M Liu
- Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242, USA
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43
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Jansa P, Mason SW, Hoffmann-Rohrer U, Grummt I. Cloning and functional characterization of PTRF, a novel protein which induces dissociation of paused ternary transcription complexes. EMBO J 1998; 17:2855-64. [PMID: 9582279 PMCID: PMC1170626 DOI: 10.1093/emboj/17.10.2855] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Termination of transcription by RNA polymerase I (Pol I) is a two-step process which involves pausing of elongating transcription complexes and release of both pre-rRNA and Pol I from the template. In mouse, pausing of elongation complexes is mediated by the transcription termination factor TTF-I bound to the 'Sal box' terminator downstream of the rDNA transcription unit. Dissociation of paused ternary complexes requires a cellular factor, termed PTRF for Pol I and transcript release factor. Here we describe the molecular cloning of a cDNA corresponding to murine PTRF. Recombinant PTRF is capable of dissociating ternary Pol I transcription complexes in vitro as revealed by release of both Pol I and nascent transcripts from the template. Consistent with its function in transcription termination, PTRF interacts with both TTF-I and Pol I. Moreover, we demonstrate specific binding of PTRF to transcripts containing the 3' end of pre-rRNA. Substitution of 3'-terminal uridylates by guanine residues abolishes PTRF binding and impairs release activity. The results reveal a network of protein-protein and protein-nucleic acid interactions that governs termination of Pol I transcription.
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Affiliation(s)
- P Jansa
- Division of Molecular Biology of the Cell II, German Cancer Research Center, Heidelberg, Germany
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