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Diao AJ, Su BG, Vos SM. Pause Patrol: Negative Elongation Factor's Role in Promoter-Proximal Pausing and Beyond. J Mol Biol 2025; 437:168779. [PMID: 39241983 DOI: 10.1016/j.jmb.2024.168779] [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: 06/28/2024] [Revised: 08/27/2024] [Accepted: 08/30/2024] [Indexed: 09/09/2024]
Abstract
RNA polymerase (Pol) II is highly regulated to ensure appropriate gene expression. Early transcription elongation is associated with transient pausing of RNA Pol II in the promoter-proximal region. In multicellular organisms, this pausing is stabilized by the association of transcription elongation factors DRB-sensitivity inducing factor (DSIF) and Negative Elongation Factor (NELF). DSIF is a broadly conserved transcription elongation factor whereas NELF is mostly restricted to the metazoan lineage. Mounting evidence suggests that NELF association with RNA Pol II serves as checkpoint for either release into rapid and productive transcription elongation or premature termination at promoter-proximal pause sites. Here we summarize NELF's roles in promoter-proximal pausing, transcription termination, DNA repair, and signaling based on decades of cell biological, biochemical, and structural work and describe areas for future research.
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Affiliation(s)
- Annette J Diao
- Department of Biology, Massachusetts Institute of Technology, Building 68, 31 Ames St., Cambridge, MA 02139, United States
| | - Bonnie G Su
- Department of Biology, Massachusetts Institute of Technology, Building 68, 31 Ames St., Cambridge, MA 02139, United States
| | - Seychelle M Vos
- Department of Biology, Massachusetts Institute of Technology, Building 68, 31 Ames St., Cambridge, MA 02139, United States; Howard Hughes Medical Institute, United States.
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2
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Mora Gallardo C, Sánchez de Diego A, Martínez-A C, van Wely KHM. Interplay between splicing and transcriptional pausing exerts genome-wide control over alternative polyadenylation. Transcription 2021; 12:55-71. [PMID: 34365909 PMCID: PMC8555548 DOI: 10.1080/21541264.2021.1959244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recent studies have identified multiple polyadenylation sites in nearly all mammalian genes. Although these are interpreted as evidence for alternative polyadenylation, our knowledge of the underlying mechanisms is still limited. Most studies only consider the immediate surroundings of gene ends, even though in vitro experiments have uncovered the involvement of external factors such as splicing. Whereas in vivo splicing manipulation was impracticable until recently, we now used mutants in the Death Inducer Obliterator (DIDO) gene to study their impact on 3ʹ end processing. We observe multiple rounds of readthrough and gene fusions, suggesting that no arbitration between polyadenylation sites occurs. Instead, a window of opportunity seems to control end processing. Through the identification of T-rich sequence motifs, our data indicate that splicing and transcriptional pausing interact to regulate alternative polyadenylation. We propose that 3ʹ splice site activation comprises a variable timer, which determines how long transcription proceeds before polyadenylation signals are recognized. Thus, the role of core polyadenylation signals could be more passive than commonly believed. Our results provide new insights into the mechanisms of alternative polyadenylation and expand the catalog of related aberrations. Abbreviations APA: alternative polyadenylation; bp: basepair; MEF: mouse embryonic fibroblasts; PA: polyadenylation; PAS: polyadenylation site; Pol II: (RNA) polymerase II ; RT-PCR:reverse-transcriptase PCR; SF:splicing factor; SFPQ:splicing factor rich in proline and glutamine; SS:splice site; TRSM:Thymidine rich sequence motif; UTR:untranslated terminal region
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Affiliation(s)
- Carmen Mora Gallardo
- Department of Immunology and Oncology Centro Nacional De Biotecnología (CNB)/, CSIC Darwin 3, Campus UAM Cantoblanco, Madrid, Spain
| | - Ainhoa Sánchez de Diego
- Department of Immunology and Oncology Centro Nacional De Biotecnología (CNB)/, CSIC Darwin 3, Campus UAM Cantoblanco, Madrid, Spain
| | - Carlos Martínez-A
- Department of Immunology and Oncology Centro Nacional De Biotecnología (CNB)/, CSIC Darwin 3, Campus UAM Cantoblanco, Madrid, Spain
| | - Karel H M van Wely
- Department of Immunology and Oncology Centro Nacional De Biotecnología (CNB)/, CSIC Darwin 3, Campus UAM Cantoblanco, Madrid, Spain
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3
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Scull CE, Lucius AL, Schneider DA. The N-terminal domain of the A12.2 subunit stimulates RNA polymerase I transcription elongation. Biophys J 2021; 120:1883-1893. [PMID: 33737158 DOI: 10.1016/j.bpj.2021.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 01/26/2021] [Accepted: 03/09/2021] [Indexed: 11/30/2022] Open
Abstract
Eukaryotes express three DNA-dependent RNA polymerases (Pols) that are responsible for the entirety of cellular genomic expression. The three Pols have evolved to express specific cohorts of RNAs and thus have diverged both structurally and functionally to efficiently execute their specific transcriptional roles. One example of this divergence is Pol I's inclusion of a proofreading factor as a bona fide subunit, as opposed to Pol II, which recruits a transcription factor, TFIIS, for proofreading. The A12.2 (A12) subunit of Pol I shares homology with both the Rpb9 subunit of Pol II as well as the transcription factor TFIIS, which promotes RNA cleavage and proofreading by Pol II. In this study, the functional contribution of the TFIIS-like C-terminal domain and the Rpb9-like N-terminal domain of the A12 subunit are probed through mutational analysis. We found that a Pol I mutant lacking the C-terminal domain of the A12 subunit (ΔA12CTD Pol I) is slightly faster than wild-type Pol I in single-nucleotide addition, but ΔA12CTD Pol I lacks RNA cleavage activity. ΔA12CTD Pol I is likewise similar to wild-type Pol I in elongation complex stability, whereas removal of the entire A12 subunit (ΔA12 Pol I) was previously demonstrated to stabilize transcription elongation complexes. Furthermore, the ΔA12CTD Pol I is sensitive to downstream sequence context, as ΔA12CTD Pol I exposed to AT-rich downstream DNA is more arrest prone than ΔA12 Pol I. These data demonstrate that the N-terminal domain of A12 does not stimulate Pol I intrinsic RNA cleavage activity, but rather contributes to core transcription elongation properties of Pol I.
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Affiliation(s)
- Catherine E Scull
- The Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Aaron L Lucius
- the Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama
| | - David A Schneider
- The Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama.
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4
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Stagsted LVW, O'Leary ET, Ebbesen KK, Hansen TB. The RNA-binding protein SFPQ preserves long-intron splicing and regulates circRNA biogenesis in mammals. eLife 2021; 10:e63088. [PMID: 33476259 PMCID: PMC7819710 DOI: 10.7554/elife.63088] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022] Open
Abstract
Circular RNAs (circRNAs) represent an abundant and conserved entity of non-coding RNAs; however, the principles of biogenesis are currently not fully understood. Here, we identify two factors, splicing factor proline/glutamine rich (SFPQ) and non-POU domain-containing octamer-binding protein (NONO), to be enriched around circRNA loci. We observe a subclass of circRNAs, coined DALI circRNAs, with distal inverted Alu elements and long flanking introns to be highly deregulated upon SFPQ knockdown. Moreover, SFPQ depletion leads to increased intron retention with concomitant induction of cryptic splicing, premature transcription termination, and polyadenylation, particularly prevalent for long introns. Aberrant splicing in the upstream and downstream regions of circRNA producing exons are critical for shaping the circRNAome, and specifically, we identify missplicing in the immediate upstream region to be a conserved driver of circRNA biogenesis. Collectively, our data show that SFPQ plays an important role in maintaining intron integrity by ensuring accurate splicing of long introns, and disclose novel features governing Alu-independent circRNA production.
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5
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Scull CE, Clarke AM, Lucius AL, Schneider DA. Downstream sequence-dependent RNA cleavage and pausing by RNA polymerase I. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49886-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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6
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Scull CE, Clarke AM, Lucius AL, Schneider DA. Downstream sequence-dependent RNA cleavage and pausing by RNA polymerase I. J Biol Chem 2019; 295:1288-1299. [PMID: 31843971 DOI: 10.1074/jbc.ra119.011354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/03/2019] [Indexed: 01/12/2023] Open
Abstract
The sequence of the DNA template has long been thought to influence the rate of transcription by DNA-dependent RNA polymerases, but the influence of DNA sequence on transcription elongation properties of eukaryotic RNA polymerase I (Pol I) from Saccharomyces cerevisiae has not been defined. In this study, we observe changes in dinucleotide production, transcription elongation complex stability, and Pol I pausing in vitro in response to downstream DNA. In vitro studies demonstrate that AT-rich downstream DNA enhances pausing by Pol I and inhibits Pol I nucleolytic cleavage activity. Analysis of Pol I native elongating transcript sequencing data in Saccharomyces cerevisiae suggests that these downstream sequence elements influence Pol I in vivo Native elongating transcript sequencing studies reveal that Pol I occupancy increases as downstream AT content increases and decreases as downstream GC content increases. Collectively, these data demonstrate that the downstream DNA sequence directly impacts the kinetics of transcription elongation prior to the sequence entering the active site of Pol I both in vivo and in vitro.
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Affiliation(s)
- Catherine E Scull
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Andrew M Clarke
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Aaron L Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - David Alan Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294
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7
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Mora Gallardo C, Sánchez de Diego A, Gutiérrez Hernández J, Talavera-Gutiérrez A, Fischer T, Martínez-A C, van Wely KHM. Dido3-dependent SFPQ recruitment maintains efficiency in mammalian alternative splicing. Nucleic Acids Res 2019; 47:5381-5394. [PMID: 30931476 PMCID: PMC6547428 DOI: 10.1093/nar/gkz235] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/19/2019] [Accepted: 03/22/2019] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing is facilitated by accessory proteins that guide spliceosome subunits to the primary transcript. Many of these splicing factors recognize the RNA polymerase II tail, but SFPQ is a notable exception even though essential for mammalian RNA processing. This study reveals a novel role for Dido3, one of three Dido gene products, in alternative splicing. Binding of the Dido3 amino terminus to histones and to the polymerase jaw domain was previously reported, and here we show interaction between its carboxy terminus and SFPQ. We generated a mutant that eliminates Dido3 but preserves other Dido gene products, mimicking reduced Dido3 levels in myeloid neoplasms. Dido mutation suppressed SFPQ binding to RNA and increased skipping for a large group of exons. Exons bearing recognition sequences for alternative splicing factors were nonetheless included more efficiently. Reduced SFPQ recruitment may thus account for increased skipping of SFPQ-dependent exons, but could also generate a splicing factor surplus that becomes available to competing splice sites. Taken together, our data indicate that Dido3 is an adaptor that controls SFPQ utilization in RNA splicing. Distributing splicing factor recruitment over parallel pathways provides mammals with a simple mechanism to regulate exon usage while maintaining RNA splicing efficiency.
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Affiliation(s)
- Carmen Mora Gallardo
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Ainhoa Sánchez de Diego
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Julio Gutiérrez Hernández
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Amaia Talavera-Gutiérrez
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Thierry Fischer
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Carlos Martínez-A
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
| | - Karel H M van Wely
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB)/CSIC, Darwin 3, Campus UAM Cantoblanco, 28049 Madrid, Spain
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8
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Saba J, Chua XY, Mishanina TV, Nayak D, Windgassen TA, Mooney RA, Landick R. The elemental mechanism of transcriptional pausing. eLife 2019; 8:e40981. [PMID: 30618376 PMCID: PMC6336406 DOI: 10.7554/elife.40981] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Transcriptional pausing underlies regulation of cellular RNA biogenesis. A consensus pause sequence that acts on RNA polymerases (RNAPs) from bacteria to mammals halts RNAP in an elemental paused state from which longer-lived pauses can arise. Although the structural foundations of pauses prolonged by backtracking or nascent RNA hairpins are recognized, the fundamental mechanism of the elemental pause is less well-defined. Here we report a mechanistic dissection that establishes the elemental pause signal (i) is multipartite; (ii) causes a modest conformational shift that puts γ-proteobacterial RNAP in an off-pathway state in which template base loading but not RNA translocation is inhibited; and (iii) allows RNAP to enter pretranslocated and one-base-pair backtracked states easily even though the half-translocated state observed in paused cryo-EM structures rate-limits pause escape. Our findings provide a mechanistic basis for the elemental pause and a framework to understand how pausing is modulated by sequence, cellular conditions, and regulators.
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Affiliation(s)
- Jason Saba
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Xien Yu Chua
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Tatiana V Mishanina
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Dhananjaya Nayak
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Tricia A Windgassen
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Rachel Anne Mooney
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
| | - Robert Landick
- Department of BiochemistryUniversity of Wisconsin-MadisonMadisonUnited States
- Department of BacteriologyUniversity of Wisconsin-MadisonMadisonUnited States
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9
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Castro-Gonzalez S, Colomer-Lluch M, Serra-Moreno R. Barriers for HIV Cure: The Latent Reservoir. AIDS Res Hum Retroviruses 2018; 34:739-759. [PMID: 30056745 PMCID: PMC6152859 DOI: 10.1089/aid.2018.0118] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Thirty-five years after the identification of HIV-1 as the causative agent of AIDS, we are still in search of vaccines and treatments to eradicate this devastating infectious disease. Progress has been made in understanding the molecular pathogenesis of this infection, which has been crucial for the development of the current therapy regimens. However, despite their efficacy at limiting active viral replication, these drugs are unable to purge the latent reservoir: a pool of cells that harbor transcriptionally inactive, but replication-competent HIV-1 proviruses, and that represent the main barrier to eradicate HIV-1 from affected individuals. In this review, we discuss advances in the field that have allowed a better understanding of HIV-1 latency, including the diverse cell types that constitute the latent reservoir, factors influencing latency, tools to study HIV-1 latency, as well as current and prospective therapeutic approaches to target these latently infected cells, so a functional cure for HIV/AIDS can become a reality.
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Affiliation(s)
- Sergio Castro-Gonzalez
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, Texas
| | - Marta Colomer-Lluch
- IrsiCaixa AIDS Research Institute, Hospital Germans Trias i Pujol, Badalona, Spain
| | - Ruth Serra-Moreno
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, Texas
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10
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Vos SM, Farnung L, Urlaub H, Cramer P. Structure of paused transcription complex Pol II-DSIF-NELF. Nature 2018; 560:601-606. [PMID: 30135580 PMCID: PMC6245578 DOI: 10.1038/s41586-018-0442-2] [Citation(s) in RCA: 262] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/17/2018] [Indexed: 11/24/2022]
Abstract
Metazoan gene regulation often involves the pausing of RNA polymerase II (Pol II) in the promoter-proximal region. Paused Pol II is stabilized by the protein complexes DRB sensitivity-inducing factor (DSIF) and negative elongation factor (NELF). Here we report the cryo-electron microscopy structure of a paused transcription elongation complex containing Sus scrofa Pol II and Homo sapiens DSIF and NELF at 3.2 Å resolution. The structure reveals a tilted DNA-RNA hybrid that impairs binding of the nucleoside triphosphate substrate. NELF binds the polymerase funnel, bridges two mobile polymerase modules, and contacts the trigger loop, thereby restraining Pol II mobility that is required for pause release. NELF prevents binding of the anti-pausing transcription elongation factor IIS (TFIIS). Additionally, NELF possesses two flexible 'tentacles' that can contact DSIF and exiting RNA. These results define the paused state of Pol II and provide the molecular basis for understanding the function of NELF during promoter-proximal gene regulation.
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Affiliation(s)
- Seychelle M Vos
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Lucas Farnung
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany
| | - Henning Urlaub
- Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, Göttingen, Germany
- University Medical Center Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Göttingen, Germany
| | - Patrick Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany.
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11
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Abstract
The known diversity of metabolic strategies and physiological adaptations of archaeal species to extreme environments is extraordinary. Accurate and responsive mechanisms to ensure that gene expression patterns match the needs of the cell necessitate regulatory strategies that control the activities and output of the archaeal transcription apparatus. Archaea are reliant on a single RNA polymerase for all transcription, and many of the known regulatory mechanisms employed for archaeal transcription mimic strategies also employed for eukaryotic and bacterial species. Novel mechanisms of transcription regulation have become apparent by increasingly sophisticated in vivo and in vitro investigations of archaeal species. This review emphasizes recent progress in understanding archaeal transcription regulatory mechanisms and highlights insights gained from studies of the influence of archaeal chromatin on transcription.
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12
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Windgassen TA, Mooney RA, Nayak D, Palangat M, Zhang J, Landick R. Trigger-helix folding pathway and SI3 mediate catalysis and hairpin-stabilized pausing by Escherichia coli RNA polymerase. Nucleic Acids Res 2014; 42:12707-21. [PMID: 25336618 PMCID: PMC4227799 DOI: 10.1093/nar/gku997] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The conformational dynamics of the polymorphous trigger loop (TL) in RNA polymerase (RNAP) underlie multiple steps in the nucleotide addition cycle and diverse regulatory mechanisms. These mechanisms include nascent RNA hairpin-stabilized pausing, which inhibits TL folding into the trigger helices (TH) required for rapid nucleotide addition. The nascent RNA pause hairpin forms in the RNA exit channel and promotes opening of the RNAP clamp domain, which in turn stabilizes a partially folded, paused TL conformation that disfavors TH formation. We report that inhibiting TH unfolding with a disulfide crosslink slowed multiround nucleotide addition only modestly but eliminated hairpin-stabilized pausing. Conversely, a substitution that disrupts the TH folding pathway and uncouples establishment of key TH–NTP contacts from complete TH formation and clamp movement allowed rapid catalysis and eliminated hairpin-stabilized pausing. We also report that the active-site distal arm of the TH aids TL folding, but that a 188-aa insertion in the Escherichia coli TL (sequence insertion 3; SI3) disfavors TH formation and stimulates pausing. The effect of SI3 depends on the jaw domain, but not on downstream duplex DNA. Our results support the view that both SI3 and the pause hairpin modulate TL folding in a constrained pathway of intermediate states.
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Affiliation(s)
- Tricia A Windgassen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Rachel Anne Mooney
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Dhananjaya Nayak
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Murali Palangat
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jinwei Zhang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
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13
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Larson MH, Mooney RA, Peters JM, Windgassen T, Nayak D, Gross CA, Block SM, Greenleaf WJ, Landick R, Weissman JS. A pause sequence enriched at translation start sites drives transcription dynamics in vivo. Science 2014; 344:1042-7. [PMID: 24789973 DOI: 10.1126/science.1251871] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Transcription by RNA polymerase (RNAP) is interrupted by pauses that play diverse regulatory roles. Although individual pauses have been studied in vitro, the determinants of pauses in vivo and their distribution throughout the bacterial genome remain unknown. Using nascent transcript sequencing, we identified a 16-nucleotide consensus pause sequence in Escherichia coli that accounts for known regulatory pause sites as well as ~20,000 new in vivo pause sites. In vitro single-molecule and ensemble analyses demonstrate that these pauses result from RNAP-nucleic acid interactions that inhibit next-nucleotide addition. The consensus sequence also leads to pausing by RNAPs from diverse lineages and is enriched at translation start sites in both E. coli and Bacillus subtilis. Our results thus reveal a conserved mechanism unifying known and newly identified pause events.
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Affiliation(s)
- Matthew H Larson
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Rachel A Mooney
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Jason M Peters
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tricia Windgassen
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Dhananjaya Nayak
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Carol A Gross
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Steven M Block
- Department of Biological Sciences, Stanford University, Stanford, CA 94025, USA. Department of Applied Physics; Stanford University, Stanford, CA 94025, USA
| | | | - Robert Landick
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA. Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, University of California, San Francisco, San Francisco, CA 94158, USA.
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14
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Affiliation(s)
- Finn Werner
- RNAP Laboratory, Institute for Structural and Molecular Biology, Division of Biosciences, University College London , Darwin Building, Gower Street, London WC1E 6BT, U.K
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15
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Kinase control prevents HIV-1 reactivation in spite of high levels of induced NF-κB activity. J Virol 2012; 86:4548-58. [PMID: 22345467 DOI: 10.1128/jvi.06726-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Despite its clinical importance, the molecular biology of HIV-1 latency control is at best partially understood, and the literature remains conflicting. The most recent description that latent HIV-1 is integrated into actively expressed host genes has further confounded the situation. This lack of molecular understanding complicates our efforts to identify therapeutic compounds or strategies that could reactivate latent HIV-1 infection in patients, a prerequisite for the eradication of HIV-1 infection. Currently, many therapeutic development efforts operate under the assumption that a restrictive histone code could govern latent infection and that either dissipation of the histone-based restrictions or NF-κB activation could be sufficient to trigger HIV-1 reactivation. We here present data that suggest an additional, higher level of molecular control. During a high-content drug screening effort, we identified AS601245 as a potent inhibitor of HIV-1 reactivation in latently infected primary T cells and T cell lines. In either system, AS601245 inhibited HIV-1 reactivation despite high levels of induced NF-κB activation. This finding suggests the presence of a gatekeeper kinase activity that controls latent HIV-1 infection even in the presence of high levels of NF-κB activity. Potential therapeutic stimuli that do not target this gatekeeper kinase will likely fail to trigger efficient system-wide HIV-1 reactivation.
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16
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Kireeva ML, Domecq C, Coulombe B, Burton ZF, Kashlev M. Interaction of RNA polymerase II fork loop 2 with downstream non-template DNA regulates transcription elongation. J Biol Chem 2011; 286:30898-30910. [PMID: 21730074 DOI: 10.1074/jbc.m111.260844] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fork loop 2 is a small semiconservative segment of the larger fork domain in the second largest Rpb2 subunit of RNA polymerase II (Pol II). This flexible loop, juxtaposed at the leading edge of transcription bubble, has been proposed to participate in DNA strand separation, translocation along DNA, and NTP loading to Pol II during elongation. Here we show that the Rpb2 mutant carrying a deletion of the flexible part of the loop is not lethal in yeast. The mutation exhibits no defects in DNA melting and translocation in vitro but confers a moderate decrease of the catalytic activity of the enzyme caused by the impaired sequestration of the NTP substrate in the active center prior to catalysis. In the structural model of the Pol II elongation complex, fork loop 2 directly interacts with an unpaired DNA residue in the non-template DNA strand one nucleotide ahead from the active center (the i+2 position). We showed that elimination of this putative interaction by replacement of the i+2 residue with an abasic site inhibits Pol II activity to the same degree as the deletion of fork loop 2. This replacement has no detectable effect on the activity of the mutant enzyme. We provide direct evidence that interaction of fork loop 2 with the non-template DNA strand facilitates NTP sequestration through interaction with the adjacent segment of the fork domain involved in the active center of Pol II.
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Affiliation(s)
- Maria L Kireeva
- NCI-Frederick, National Institutes of Health, Center for Cancer Research, Frederick, Maryland 21702-1201
| | - Céline Domecq
- Gene Transcription and Proteomics Laboratory, Institut de Recherches Cliniques de Montréal and Department of Biochemistry, Université de Montréal, Montréal, Québec, H2W 1R7 Canada
| | - Benoit Coulombe
- Gene Transcription and Proteomics Laboratory, Institut de Recherches Cliniques de Montréal and Department of Biochemistry, Université de Montréal, Montréal, Québec, H2W 1R7 Canada
| | - Zachary F Burton
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319
| | - Mikhail Kashlev
- NCI-Frederick, National Institutes of Health, Center for Cancer Research, Frederick, Maryland 21702-1201.
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17
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Templated nucleoside triphosphate binding to a noncatalytic site on RNA polymerase regulates transcription. Proc Natl Acad Sci U S A 2011; 108:6079-84. [PMID: 21447716 DOI: 10.1073/pnas.1011274108] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The regulation of RNA synthesis by RNA polymerase (RNAP) is essential for proper gene expression. Crystal structures of RNAP reveal two channels: the main channel that contains the downstream DNA and a secondary channel that leads directly to the catalytic site. Although nucleoside triphosphates (NTPs) have been seen only in the catalytic site and the secondary channel in these structures, several models of transcription elongation, based on biochemical studies, propose that template-dependent binding of NTPs in the main channel regulates RNA synthesis. These models, however, remain controversial. We used transient state kinetics and a mutant of RNAP to investigate the role of the main channel in regulating nucleotide incorporation. Our data indicate that a NTP specific for the i + 2 template position can bind to a noncatalytic site and increase the rate of RNA synthesis and that the NTP bound to this site can be shuttled directly into the catalytic site. We also identify fork loop 2, which lies across from the downstream DNA, as a functional component of this site. Taken together, our data support the existence of a noncatalytic template-specific NTP binding site in the main channel that is involved in the regulation of nucleotide incorporation. NTP binding to this site could promote high-fidelity processive synthesis under a variety of environmental conditions and allow DNA sequence-mediated regulatory signals to be communicated to the active site.
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18
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Gan Q, Schones DE, Ho Eun S, Wei G, Cui K, Zhao K, Chen X. Monovalent and unpoised status of most genes in undifferentiated cell-enriched Drosophila testis. Genome Biol 2010; 11:R42. [PMID: 20398323 PMCID: PMC2884545 DOI: 10.1186/gb-2010-11-4-r42] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 02/26/2010] [Accepted: 04/15/2010] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Increasing evidence demonstrates that stem cells maintain their identities by a unique transcription network and chromatin structure. Opposing epigenetic modifications H3K27 me3 and H3K4 me3 have been proposed to label differentiation-associated genes in stem cells, progenitor and precursor cells. In addition, many differentiation-associated genes are maintained at a poised status by recruitment of the initiative RNA Polymerase II (Pol II) at their promoter regions, in preparation for lineage-specific expression upon differentiation. Previous studies have been performed using cultured mammalian embryonic stem cells. To a lesser extent, chromatin structure has been delineated in other model organisms, such as Drosophila, to open new avenues for genetic analyses. RESULTS Here we use testes isolated from a Drosophila bag of marbles mutant strain, from which germ cells are in their undifferentiated status. We use these testes to study the endogenous chromatin structure of undifferentiated cells using ChIP-seq. We integrate the ChIP-seq with RNA-seq data, which measures the digital transcriptome. Our genome-wide analyses indicate that most differentiation-associated genes in undifferentiated cells lack an active chromatin mark and initiative Pol II; instead, they are associated with either the repressive H3K27 me3 mark or no detectable mark. CONCLUSIONS Our results reveal that most of the differentiation-associated genes in undifferentiated-cell-enriched Drosophila testes are associated with monovalent but not bivalent modifications, a chromatin signature that is distinct from the data reported in mammalian stem or precursor cells, which may reflect cell type specificity, species specificity, or both.
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Affiliation(s)
- Qiang Gan
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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19
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Herbert KM, Zhou J, Mooney RA, Porta AL, Landick R, Block SM. E. coli NusG inhibits backtracking and accelerates pause-free transcription by promoting forward translocation of RNA polymerase. J Mol Biol 2010; 399:17-30. [PMID: 20381500 DOI: 10.1016/j.jmb.2010.03.051] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 03/25/2010] [Accepted: 03/26/2010] [Indexed: 10/19/2022]
Abstract
NusG is an essential transcription factor in Escherichia coli that is capable of increasing the overall rate of transcription. Transcript elongation by RNA polymerase (RNAP) is frequently interrupted by pauses of varying durations, and NusG is known to decrease the occupancy of at least some paused states. However, it has not been established whether NusG enhances transcription chiefly by (1) increasing the rate of elongation between pauses, (2) reducing the lifetimes of pauses, or (3) reducing the rate of entry into paused states. Here, we studied transcription by single molecules of RNAP under various conditions of ribonucleoside triphosphate concentration, applied load, and temperature, using an optical trapping assay capable of distinguishing pauses as brief as 1 s. We found that NusG increases the rate of elongation, that is, the pause-free velocity along the template. Because pauses are off-pathway states that compete with elongation, we observed a concomitant decrease in the rate of entry into short-lifetime, paused states. The effects on short pauses and elongation were comparatively modest, however. More dramatic was the effect of NusG on suppressing entry into long-lifetime ("stabilized") pauses. Because a significant fraction of the time required for the transcription of a typical gene may be occupied by long pauses, NusG is capable of exerting a significant modulatory effect on the rates of RNA synthesis. The observed properties of NusG were consistent with a unified model where the function of this accessory factor is to promote transcriptionally downstream motion of the enzyme along the DNA template, which has the effect of forward-biasing RNAP from the pre-translocated state toward the post-translocated state.
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20
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Nechooshtan G, Elgrably-Weiss M, Sheaffer A, Westhof E, Altuvia S. A pH-responsive riboregulator. Genes Dev 2009; 23:2650-62. [PMID: 19933154 DOI: 10.1101/gad.552209] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The locus alx, which encodes a putative transporter, was discovered previously in a screen for genes induced under extreme alkaline conditions. Here we show that the RNA region preceding the alx ORF acts as a pH-responsive element, which, in response to high pH, leads to an increase in alx expression. Under normal growth conditions this RNA region forms a translationally inactive structure, but when exposed to high pH, a translationally active structure is formed to produce Alx. Formation of the active structure occurs while transcription is in progress under alkaline conditions and involves pausing of RNA polymerase at two distinct sites. Alkali increases the longevity of pausing at these sites and thereby interferes with formation of the inactive structure and promotes folding of the active one. The alx locus represents the first example of a pH-responsive riboregulator of gene expression, introducing a novel regulatory mechanism that involves RNA folding dynamics driven by pH.
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Affiliation(s)
- Gal Nechooshtan
- Department of Microbiology and Molecular Genetics, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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21
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Rhee AC, Somerlot BH, Parimi N, Gott JM. Distinct roles for sequences upstream of and downstream from Physarum editing sites. RNA (NEW YORK, N.Y.) 2009; 15:1753-1765. [PMID: 19605532 PMCID: PMC2743052 DOI: 10.1261/rna.1668309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 06/06/2009] [Indexed: 05/28/2023]
Abstract
RNAs in the mitochondria of Physarum polycephalum contain nonencoded nucleotides that are added during RNA synthesis. Essentially all steady-state RNAs are accurately and fully edited, yet the signals guiding these precise nucleotide insertions are presently unknown. To localize the regions of the template that are required for editing, we constructed a series of chimeric templates that substitute varying amounts of DNA either upstream of or downstream from C insertion sites. Remarkably, all sequences necessary for C addition are contained within approximately 9 base pairs on either side of the insertion site. In addition, our data strongly suggest that sequences within this critical region affect different steps in the editing reaction. Template alterations upstream of an editing site influence nucleotide selection and/or insertion, while downstream changes affect editing site recognition and templated extension from the added, unpaired nucleotide. The data presented here provide the first evidence that individual regions of the DNA template play discrete mechanistic roles and represent a crucial initial step toward defining the source of the editing specificity in Physarum mitochondria. In addition, these findings have mechanistic implications regarding the potential involvement of the mitochondrial RNA polymerase in the editing reaction.
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Affiliation(s)
- Amy C Rhee
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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22
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Sydow JF, Brueckner F, Cheung ACM, Damsma GE, Dengl S, Lehmann E, Vassylyev D, Cramer P. Structural basis of transcription: mismatch-specific fidelity mechanisms and paused RNA polymerase II with frayed RNA. Mol Cell 2009; 34:710-21. [PMID: 19560423 DOI: 10.1016/j.molcel.2009.06.002] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/05/2009] [Accepted: 06/05/2009] [Indexed: 11/17/2022]
Abstract
We show that RNA polymerase (Pol) II prevents erroneous transcription in vitro with different strategies that depend on the type of DNARNA base mismatch. Certain mismatches are efficiently formed but impair RNA extension. Other mismatches allow for RNA extension but are inefficiently formed and efficiently proofread by RNA cleavage. X-ray analysis reveals that a TU mismatch impairs RNA extension by forming a wobble base pair at the Pol II active center that dissociates the catalytic metal ion and misaligns the RNA 3' end. The mismatch can also stabilize a paused state of Pol II with a frayed RNA 3' nucleotide. The frayed nucleotide binds in the Pol II pore either parallel or perpendicular to the DNA-RNA hybrid axis (fraying sites I and II, respectively) and overlaps the nucleoside triphosphate (NTP) site, explaining how it halts transcription during proofreading, before backtracking and RNA cleavage.
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Affiliation(s)
- Jasmin F Sydow
- Department of Chemistry and Biochemistry, Gene Center Munich and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
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23
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Abstract
Sequence-specific pausing of multisubunit RNA polymerases (RNAPs) represents a rate-limiting step during transcription elongation. Pausing occurs on average every 100 bases of DNA. Several models have been proposed to explain pausing, including backtracking of the ternary elongation complex, delay of translocation of the enzyme along DNA, or a conformational change in the active site preventing formation of the phosphodiester bond. Here, we performed biochemical characterization of previously-reported pauses of Escherichia coli RNAP and found that they are not associated with backtracking or a translocation delay. Instead, the paused complex contains the 3' end of the transcript in the active center and is capable of binding the next cognate NTP. However, bond formation occurs much slower in the paused complex compared with its fully-active counterpart. The pausing is dramatically decreased by a substitution of the base encoding the next incoming NTP and the base encoding the 3' end of the nascent RNA, suggesting that (mis)-alignment of the 3' end of the RNA and the incoming NTP in the active site is crucial for pausing. These pause sites are conserved between E. coli and Thermus thermophilus RNAPs, but are not recognized by Saccharomyces cerevisiae RNAP II, indicating that prokaryotic RNAPs might be more sensitive to the changes in the alignment of the nascent transcript and the substrate NTP in the active site.
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24
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Borukhov S, Nudler E. RNA polymerase: the vehicle of transcription. Trends Microbiol 2008; 16:126-34. [DOI: 10.1016/j.tim.2007.12.006] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 12/06/2007] [Accepted: 12/06/2007] [Indexed: 10/22/2022]
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25
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Spitalny P, Thomm M. A polymerase III-like reinitiation mechanism is operating in regulation of histone expression in archaea. Mol Microbiol 2007; 67:958-70. [PMID: 18182021 PMCID: PMC2253867 DOI: 10.1111/j.1365-2958.2007.06084.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An archaeal histone gene from the hyperthermophile Pyrococcus furiosus containing four consecutive putative oligo-dT terminator sequences was used as a model system to investigate termination signals and the mechanism of termination in vitro. The archaeal RNA polymerase terminated with high efficiency at the first terminator at 90°C when it contained five to six T residues, at 80°C readthrough was significantly increased. A putative hairpin structure upstream of the first terminator had no effect on termination efficiency. Template competition experiments starting with RNA polymerase molecules engaged in ternary complexes revealed recycling of RNA polymerase from the terminator to the promoter of the same template. This facilitated reinitiation was dependent upon the presence of a terminator sequence suggesting that pausing at the terminator is required for recycling as in the RNA polymerase III system. Replacement of the sequences immediately downstream of the oligo-dT terminator by an AT-rich segment improved termination efficiency. Both AT-rich and GC-rich downstream sequences seemed to impair the facilitated reinitiation pathway. Our data suggest that recycling is dependent on a subtle interplay of pausing of RNA polymerase at the terminator and RNA polymerase translocation beyond the oligo-dT termination signal that is dramatically affected by downstream sequences.
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Affiliation(s)
- Patrizia Spitalny
- Department of Microbiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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26
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Wang D, Bushnell DA, Westover KD, Kaplan CD, Kornberg RD. Structural basis of transcription: role of the trigger loop in substrate specificity and catalysis. Cell 2006; 127:941-54. [PMID: 17129781 PMCID: PMC1876690 DOI: 10.1016/j.cell.2006.11.023] [Citation(s) in RCA: 380] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 11/10/2006] [Accepted: 11/14/2006] [Indexed: 10/23/2022]
Abstract
New structures of RNA polymerase II (pol II) transcribing complexes reveal a likely key to transcription. The trigger loop swings beneath a correct nucleoside triphosphate (NTP) in the nucleotide addition site, closing off the active center and forming an extensive network of interactions with the NTP base, sugar, phosphates, and additional pol II residues. A histidine side chain in the trigger loop, precisely positioned by these interactions, may literally "trigger" phosphodiester bond formation. Recognition and catalysis are thus coupled, ensuring the fidelity of transcription.
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Affiliation(s)
| | | | - Kenneth D. Westover
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305
| | - Craig D. Kaplan
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305
| | - Roger D. Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305
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27
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Charlet-Berguerand N, Feuerhahn S, Kong SE, Ziserman H, Conaway JW, Conaway R, Egly JM. RNA polymerase II bypass of oxidative DNA damage is regulated by transcription elongation factors. EMBO J 2006; 25:5481-91. [PMID: 17110932 PMCID: PMC1679758 DOI: 10.1038/sj.emboj.7601403] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 10/04/2006] [Indexed: 12/15/2022] Open
Abstract
Oxidative lesions represent the most abundant DNA lesions within the cell. In the present study, we investigated the impact of the oxidative lesions 8-oxoguanine, thymine glycol and 5-hydroxyuracil on RNA polymerase II (RNA pol II) transcription using a well-defined in vitro transcription system. We found that in a purified, reconstituted transcription system, these lesions block elongation by RNA pol II to different extents, depending on the type of lesion. Suggesting the presence of a bypass activity, the block to elongation is alleviated when transcription is carried out in HeLa cell nuclear extracts. By purifying this activity, we discovered that TFIIF could promote elongation through a thymine glycol lesion. The elongation factors Elongin and CSB, but not TFIIS, can also stimulate bypass of thymine glycol lesions, whereas Elongin, CSB and TFIIS can all enhance bypass of an 8-oxoguanine lesion. By increasing the efficiency with which RNA pol II reads through oxidative lesions, elongation factors can contribute to transcriptional mutagenesis, an activity that could have implications for the generation or progression of human diseases.
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Affiliation(s)
| | - Sascha Feuerhahn
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch Cedex, CU Strasbourg, France
| | | | - Howard Ziserman
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Joan W Conaway
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Ronald Conaway
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Jean Marc Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch Cedex, CU Strasbourg, France
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, BP 10142, 67404 Illkirch Cedex 67000, CU Strasbourg, France. Tel.: +33 388 65 34 47; Fax: +33 388 65 32 01; E-mail:
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28
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Abstract
The multisubunit RNAPs (RNA polymerases) found in all cellular life forms are remarkably conserved in fundamental structure, in mechanism and in their susceptibility to sequence-dependent pausing during transcription of DNA in the absence of elongation regulators. Recent studies of both prokaryotic and eukaryotic transcription have yielded an increasing appreciation of the extent to which gene regulation is accomplished during the elongation phase of transcription. Transcriptional pausing is a fundamental enzymatic mechanism that underlies many of these regulatory schemes. In some cases, pausing functions by halting RNAP for times or at positions required for regulatory interactions. In other cases, pauses function by making RNAP susceptible to premature termination of transcription unless the enzyme is modified by elongation regulators that programme efficient gene expression. Pausing appears to occur by a two-tiered mechanism in which an initial rearrangement of the enzyme's active site interrupts active elongation and puts RNAP in an elemental pause state from which additional rearrangements or regulator interactions can create long-lived pauses. Recent findings from biochemical and single-molecule transcription experiments, coupled with the invaluable availability of RNAP crystal structures, have produced attractive hypotheses to explain the fundamental mechanism of pausing.
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Affiliation(s)
- R Landick
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53705, USA.
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29
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Nag A, Narsinh K, Kazerouninia A, Martinson HG. The conserved AAUAAA hexamer of the poly(A) signal can act alone to trigger a stable decrease in RNA polymerase II transcription velocity. RNA (NEW YORK, N.Y.) 2006; 12:1534-44. [PMID: 16775304 PMCID: PMC1524889 DOI: 10.1261/rna.103206] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In vivo the poly(A) signal not only directs 3'-end processing but also controls the rate and extent of transcription. Thus, upon crossing the poly(A) signal RNA polymerase II first pauses and then terminates. We show that the G/U-rich region of the poly(A) signal, although required for termination in vivo, is not required for poly(A)-dependent pausing either in vivo or in vitro. Consistent with this, neither CstF, which recognizes the G/U-rich element, nor the polymerase CTD, which binds CstF, is required for pausing. The only part of the poly(A) signal required to direct the polymerase to pause is the AAUAAA hexamer. The effect of the hexamer on the polymerase is long lasting--in many situations polymerases over 1 kb downstream of the hexamer continue to exhibit delayed progress down the template in vivo. The hexamer is the first part of the poly(A) signal to emerge from the polymerase and may play a role independent of the rest of the poly(A) signal in paving the way for subsequent events such as 3'-end processing and termination of transcription.
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Affiliation(s)
- Anita Nag
- Department of Chemistry and Biochemistry, University of California at Los Angeles, CA 90095-1569, USA
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30
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Ederth J, Mooney RA, Isaksson LA, Landick R. Functional Interplay between the Jaw Domain of Bacterial RNA Polymerase and Allele-specific Residues in the Product RNA-binding Pocket. J Mol Biol 2006; 356:1163-79. [PMID: 16405998 DOI: 10.1016/j.jmb.2005.11.080] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2005] [Revised: 11/22/2005] [Accepted: 11/23/2005] [Indexed: 11/23/2022]
Abstract
Bacterial RNA polymerase (RNAP) is a complex molecular machine in which the network of interacting parts and their movements, including contacts to nascent RNA and the DNA template, are at best partially understood. The jaw domain is a part of RNAP that makes a key contact to duplex DNA as it enters the enzyme from downstream and also contacts two other parts of RNAP, the trigger loop, which lies in the RNAP secondary channel, and a sequence insertion in the Escherichia coli RNAP trigger loop that forms an external domain and also contacts downstream DNA. Deletion of the jaw domain causes defects in transcriptional pausing and in bacterial growth. We report here that these defects can be partially corrected by a limited set of substitutions in a distant part of RNAP, the product RNA-binding pocket. The product RNA-binding pocket binds nascent RNA upstream of the active site and is the binding site for the RNAP inhibitor rifampicin when RNA is absent. These substitutions have little effect on transcript elongation between pause sites and actually exacerbate jaw-deletion defects in transcription initiation, suggesting that the pausing defects may be principally responsible for the in vivo phenotype of the jaw deletion. We suggest that the counteracting effects on pausing of the alterations in the jaw and the product RNA binding site may be mediated either by effects on translocation or via allosteric communication to the RNAP active site.
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Affiliation(s)
- Josefine Ederth
- Department of Genetics Microbiology & Toxicology, Stockholm University, SE-10691 Stockholm, Sweden
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31
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Zhang Z, Gilmour DS. Pcf11 is a termination factor in Drosophila that dismantles the elongation complex by bridging the CTD of RNA polymerase II to the nascent transcript. Mol Cell 2006; 21:65-74. [PMID: 16387654 DOI: 10.1016/j.molcel.2005.11.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Revised: 10/17/2005] [Accepted: 11/02/2005] [Indexed: 10/25/2022]
Abstract
The mechanism by which Pol II terminates transcription in metazoans is not understood. We show that Pcf11 is directly involved in termination in Drosophila. dPcf11 is concentrated at the 3' end of the hsp70 gene in cells, and depletion of dPcf11 with RNAi causes Pol II to readthrough the normal region of termination. dPcf11 also localizes to most transcribed loci on polytene chromosomes. Biochemical analysis reveals that dPcf11 dismantles elongation complexes by a CTD-dependent but nucleotide-independent mechanism and that dPcf11 forms a bridge between the CTD and RNA. This bridge appears to be crucial because an anti-CTD antibody, which also dismantles the elongation complex, is found to bridge the CTD to RNA. dPcf11 was observed to inhibit transcription at low, but not high, nucleotide levels, suggesting that dPcf11 dismantles paused elongation complexes. These results provide a biochemical basis for the dependency of termination on pausing and the CTD in metazoans.
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Affiliation(s)
- Zhiqiang Zhang
- Department of Biochemistry and Molecular Biology, Center for Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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32
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Braglia P, Percudani R, Dieci G. Sequence context effects on oligo(dT) termination signal recognition by Saccharomyces cerevisiae RNA polymerase III. J Biol Chem 2005; 280:19551-62. [PMID: 15788403 DOI: 10.1074/jbc.m412238200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic RNA polymerase (Pol) III terminates transcription at short runs of T residues in the coding DNA strand. By genomic analysis, we found that T(5) and T(4) are the shortest Pol III termination signals in yeasts and mammals, respectively, and that, at variance with yeast, oligo(dT) terminators longer than T(5) are very rare in mammals. In Saccharomyces cerevisiae, the strength of T(5) as a terminator was found to be largely influenced by both the upstream and the downstream sequence context. In particular, the CT sequence, which is naturally present downstream of T(5) in the 3'-flank of some tDNAs, was found to act as a terminator-weakening element that facilitates translocation by reducing Pol III pausing at T(5). In contrast, tDNA transcription termination was highly efficient when T(5) was followed by an A or G residue. Surprisingly, however, when a termination-proficient T(5) signal was taken out from the tDNA context and placed downstream of a fragment of the SCR1 gene, its termination activity was compromised, both in vitro and in vivo. Even the T(6) sequence, acting as a strong terminator in tRNA gene contexts, was unexpectedly weak within the SNR52 transcription unit, where it naturally occurs. The observed sequence context effects reflect intrinsic recognition properties of Pol III, because they were still observed in a simplified in vitro transcription system only consisting of purified RNA polymerase and template DNA. Our findings strengthen the notion that termination signal recognition by Pol III is influenced in a complex way by the region surrounding the T cluster and suggest that read-through transcription beyond T clusters might play a significant role in the biogenesis of class III gene products.
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Affiliation(s)
- Priscilla Braglia
- Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Parma, Italy
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33
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Kettenberger H, Armache KJ, Cramer P. Complete RNA polymerase II elongation complex structure and its interactions with NTP and TFIIS. Mol Cell 2005; 16:955-65. [PMID: 15610738 DOI: 10.1016/j.molcel.2004.11.040] [Citation(s) in RCA: 345] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Revised: 11/19/2004] [Accepted: 11/23/2004] [Indexed: 01/22/2023]
Abstract
The crystal structure of the complete 12 subunit RNA polymerase (pol) II bound to a transcription bubble and product RNA reveals incoming template and nontemplate DNA, a seven base pair DNA/RNA hybrid, and three nucleotides each of separating DNA and RNA. The complex adopts the posttranslocation state and accommodates a cocrystallized nucleoside triphosphate (NTP) substrate. The NTP binds in the active site pore at a position to interact with a DNA template base. Residues surrounding the NTP are conserved in all cellular RNA polymerases, suggesting a universal mechanism of NTP selection and incorporation. DNA-DNA and DNA-RNA strand separation may be explained by pol II-induced duplex distortions. Four protein loops partition the active center cleft, contribute to embedding the hybrid, prevent strand reassociation, and create an RNA exit tunnel. Binding of the elongation factor TFIIS realigns RNA in the active center, possibly converting the elongation complex to an alternative state less prone to stalling.
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Affiliation(s)
- Hubert Kettenberger
- Gene Center, Department of Chemistry and Biochemistry, Ludwig-Maximilians-University of Munich, Feodor-Lynen-Str. 25, 81377 Munich, Germany
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