1
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Sawicka A, Villamil G, Lidschreiber M, Darzacq X, Dugast-Darzacq C, Schwalb B, Cramer P. Transcription activation depends on the length of the RNA polymerase II C-terminal domain. EMBO J 2021; 40:e107015. [PMID: 33555055 PMCID: PMC8090853 DOI: 10.15252/embj.2020107015] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/04/2021] [Accepted: 01/13/2021] [Indexed: 01/02/2023] Open
Abstract
Eukaryotic RNA polymerase II (Pol II) contains a tail‐like, intrinsically disordered carboxy‐terminal domain (CTD) comprised of heptad‐repeats, that functions in coordination of the transcription cycle and in coupling transcription to co‐transcriptional processes. The CTD repeat number varies between species and generally increases with genome size, but the reasons for this are unclear. Here, we show that shortening the CTD in human cells to half of its length does not generally change pre‐mRNA synthesis or processing in cells. However, CTD shortening decreases the duration of promoter‐proximal Pol II pausing, alters transcription of putative enhancer elements, and delays transcription activation after stimulation of the MAP kinase pathway. We suggest that a long CTD is required for efficient enhancer‐dependent recruitment of Pol II to target genes for their rapid activation.
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Affiliation(s)
- Anna Sawicka
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Gabriel Villamil
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Michael Lidschreiber
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Xavier Darzacq
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,CIRM Center of Excellence, University of California, Berkeley, CA, USA
| | - Claire Dugast-Darzacq
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,CIRM Center of Excellence, University of California, Berkeley, CA, USA
| | - Björn Schwalb
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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2
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Garg A, Shuman S, Schwer B. A genetic screen for suppressors of hyper-repression of the fission yeast PHO regulon by Pol2 CTD mutation T4A implicates inositol 1-pyrophosphates as agonists of precocious lncRNA transcription termination. Nucleic Acids Res 2020; 48:10739-10752. [PMID: 33010152 PMCID: PMC7641756 DOI: 10.1093/nar/gkaa776] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/03/2020] [Accepted: 09/29/2020] [Indexed: 12/23/2022] Open
Abstract
Fission yeast phosphate homeostasis genes are repressed in phosphate-rich medium by transcription of upstream lncRNAs that interferes with activation of the flanking mRNA promoters. lncRNA control of PHO gene expression is influenced by the Thr4 phospho-site in the RNA polymerase II CTD and the 3′ processing/termination factors CPF and Rhn1, mutations of which result in hyper-repression of the PHO regulon. Here, we performed a forward genetic screen for mutations that de-repress Pho1 acid phosphatase expression in CTD-T4A cells. Sequencing of 18 independent STF (Suppressor of Threonine Four) isolates revealed, in every case, a mutation in the C-terminal pyrophosphatase domain of Asp1, a bifunctional inositol pyrophosphate (IPP) kinase/pyrophosphatase that interconverts 5-IP7 and 1,5-IP8. Focused characterization of two STF strains identified 51 coding genes coordinately upregulated vis-à-vis the parental T4A strain, including all three PHO regulon genes (pho1, pho84, tgp1). Whereas these STF alleles—asp1-386(Stop) and asp1-493(Stop)—were lethal in a wild-type CTD background, they were viable in combination with mutations in CPF and Rhn1, in which context Pho1 was also de-repressed. Our findings implicate Asp1 pyrophosphatase in constraining 1,5-IP8 or 1-IP7 synthesis by Asp1 kinase, without which 1-IPPs can accumulate to toxic levels that elicit precocious termination by CPF/Rhn1.
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Affiliation(s)
- Angad Garg
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
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3
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Dannappel MV, Sooraj D, Loh JJ, Firestein R. Molecular and in vivo Functions of the CDK8 and CDK19 Kinase Modules. Front Cell Dev Biol 2019; 6:171. [PMID: 30693281 PMCID: PMC6340071 DOI: 10.3389/fcell.2018.00171] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/06/2018] [Indexed: 12/21/2022] Open
Abstract
CDK8 and its paralog, CDK19, collectively termed ‘Mediator Kinase,’ are cyclin-dependent kinases that have been implicated as key rheostats in cellular homeostasis and developmental programming. CDK8 and CDK19 are incorporated, in a mutually exclusive manner, as part of a 4-protein complex called the Mediator kinase module. This module reversibly associates with the Mediator, a 26 subunit protein complex that regulates RNA Polymerase II mediated gene expression. As part of this complex, the Mediator kinases have been implicated in diverse process such as developmental signaling, metabolic homeostasis and in innate immunity. In recent years, dysregulation of Mediator kinase module proteins, including CDK8/19, has been implicated in the development of different human diseases, and in particular cancer. This has led to intense efforts to understand how CDK8/19 regulate diverse biological outputs and develop Mediator kinase inhibitors that can be exploited therapeutically. Herein, we review both context and function of the Mediator kinases at a molecular, cellular and animal level. In so doing, we illuminate emerging concepts underpinning Mediator kinase biology and highlight certain aspects that remain unsolved.
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Affiliation(s)
- Marius Volker Dannappel
- Hudson Institute of Medical Research, Clayton, VIC, Australia.,Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia
| | - Dhanya Sooraj
- Hudson Institute of Medical Research, Clayton, VIC, Australia.,Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia
| | - Jia Jian Loh
- Hudson Institute of Medical Research, Clayton, VIC, Australia.,Faculty of Science, School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Ron Firestein
- Hudson Institute of Medical Research, Clayton, VIC, Australia.,Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia
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4
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Abstract
Alterations in the regulation of gene expression are frequently associated with developmental diseases or cancer. Transcription activation is a key phenomenon in the regulation of gene expression. In all eukaryotes, mediator of RNA polymerase II transcription (Mediator), a large complex with modular organization, is generally required for transcription by RNA polymerase II, and it regulates various steps of this process. The main function of Mediator is to transduce signals from the transcription activators bound to enhancer regions to the transcription machinery, which is assembled at promoters as the preinitiation complex (PIC) to control transcription initiation. Recent functional studies of Mediator with the use of structural biology approaches and functional genomics have revealed new insights into Mediator activity and its regulation during transcription initiation, including how Mediator is recruited to transcription regulatory regions and how it interacts and cooperates with PIC components to assist in PIC assembly. Novel roles of Mediator in the control of gene expression have also been revealed by showing its connection to the nuclear pore and linking Mediator to the regulation of gene positioning in the nuclear space. Clear links between Mediator subunits and disease have also encouraged studies to explore targeting of this complex as a potential therapeutic approach in cancer and fungal infections.
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Affiliation(s)
- Julie Soutourina
- Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, Commissariat à l'énergie Atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), University Paris Sud, University Paris Saclay, F-91198 Gif-sur-Yvette, France
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5
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Donnio LM, Bidon B, Hashimoto S, May M, Epanchintsev A, Ryan C, Allen W, Hackett A, Gecz J, Skinner C, Stevenson RE, de Brouwer APM, Coutton C, Francannet C, Jouk PS, Schwartz CE, Egly JM. MED12-related XLID disorders are dose-dependent of immediate early genes (IEGs) expression. Hum Mol Genet 2017; 26:2062-2075. [PMID: 28369444 DOI: 10.1093/hmg/ddx099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/08/2017] [Indexed: 11/13/2022] Open
Abstract
Mediator occupies a key role in protein coding genes expression in mediating the contacts between gene specific factors and the basal transcription machinery but little is known regarding the role of each Mediator subunits. Mutations in MED12 are linked with a broad spectrum of genetic disorders with X-linked intellectual disability that are difficult to range as Lujan, Opitz-Kaveggia or Ohdo syndromes. Here, we investigated several MED12 patients mutations (p.R206Q, p.N898D, p.R961W, p.N1007S, p.R1148H, p.S1165P and p.R1295H) and show that each MED12 mutations cause specific expression patterns of JUN, FOS and EGR1 immediate early genes (IEGs), reflected by the presence or absence of MED12 containing complex at their respective promoters. Moreover, the effect of MED12 mutations has cell-type specificity on IEG expression. As a consequence, the expression of late responsive genes such as the matrix metalloproteinase-3 and the RE1 silencing transcription factor implicated respectively in neural plasticity and the specific expression of neuronal genes is disturbed as documented for MED12/p.R1295H mutation. In such case, JUN and FOS failed to be properly recruited at their AP1-binding site. Our results suggest that the differences between MED12-related phenotypes are essentially the result of distinct IEGs expression patterns, the later ones depending on the accurate formation of the transcription initiation complex. This might challenge clinicians to rethink the traditional syndromes boundaries and to include genetic criterion in patients' diagnostic.
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Affiliation(s)
- Lise-Marie Donnio
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Baptiste Bidon
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Satoru Hashimoto
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France.,Department of Clinical Pharmacology and Therapeutics Oita University Faculty of Medicine, Yufu city, Oita 879-5593, Japan
| | - Melanie May
- Greenwood Genetic Center, Greenwood, SC 29649, USA
| | - Alexey Epanchintsev
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Colm Ryan
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | | | | | - Jozef Gecz
- School of Medicine, and the Robinson Research Institute, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia
| | | | | | - Arjan P M de Brouwer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, 6525?HP, The Netherlands
| | - Charles Coutton
- Département de Génétique et Procréation, Centre Hospitalier-Universitaire, Institut Albert Bonniot, CNRS/INSERM/Université Grenoble Alpes, 38000 Grenoble, France
| | - Christine Francannet
- Service de Génétique Médicale, Centre Hospitalier-Universitaire, 63003 Clermont-Ferrand, France
| | - Pierre-Simon Jouk
- Département de Génétique et Procréation, Centre Hospitalier-Universitaire, Institut Albert Bonniot, CNRS/INSERM/Université Grenoble Alpes, 38000 Grenoble, France
| | | | - Jean-Marc Egly
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
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6
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Abstract
In eukaryotes, RNA polymerase II (pol II) transcribes all protein-coding genes and many noncoding RNAs. Whereas many factors contribute to the regulation of pol II activity, the Mediator complex is required for expression of most, if not all, pol II transcripts. Structural characterization of Mediator is challenging due to its large size (∼20 subunits in yeast and 26 subunits in humans) and conformational flexibility. However, recent studies have revealed structural details at higher resolution. Here, we summarize recent findings and place in context with previous results, highlighting regions within Mediator that are important for regulating its structure and function.
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Affiliation(s)
- Thomas M Harper
- From the Department of Biochemistry, University of Colorado, Boulder, Colorado 80303
| | - Dylan J Taatjes
- From the Department of Biochemistry, University of Colorado, Boulder, Colorado 80303
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7
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Eychenne T, Werner M, Soutourina J. Toward understanding of the mechanisms of Mediator function in vivo: Focus on the preinitiation complex assembly. Transcription 2017; 8:328-342. [PMID: 28841352 DOI: 10.1080/21541264.2017.1329000] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mediator is a multisubunit complex conserved in eukaryotes that plays an essential coregulator role in RNA polymerase (Pol) II transcription. Despite intensive studies of the Mediator complex, the molecular mechanisms of its function in vivo remain to be fully defined. In this review, we will discuss the different aspects of Mediator function starting with its interactions with specific transcription factors, its recruitment to chromatin and how, as a coregulator, it contributes to the assembly of transcription machinery components within the preinitiation complex (PIC) in vivo and beyond the PIC formation.
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Affiliation(s)
- Thomas Eychenne
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France.,b Institut Pasteur, (Epi)genomics of Animal Development Unit , Development and Stem Cell Biology Department, CNRS UMR3778 , Paris , France
| | - Michel Werner
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France
| | - Julie Soutourina
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France
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8
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9
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Suk H, Knipe DM. Proteomic analysis of the herpes simplex virus 1 virion protein 16 transactivator protein in infected cells. Proteomics 2015; 15:1957-67. [PMID: 25809282 DOI: 10.1002/pmic.201500020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 02/13/2015] [Accepted: 03/18/2015] [Indexed: 01/06/2023]
Abstract
The herpes simplex virus 1 virion protein 16 (VP16) tegument protein forms a transactivation complex with the cellular proteins host cell factor 1 (HCF-1) and octamer-binding transcription factor 1 (Oct-1) upon entry into the host cell. VP16 has also been shown to interact with a number of virion tegument proteins and viral glycoprotein H to promote viral assembly, but no comprehensive study of the VP16 proteome has been performed at early times postinfection. We therefore performed a proteomic analysis of VP16-interacting proteins at 3 h postinfection. We confirmed the interaction of VP16 with HCF-1 and a large number of cellular Mediator complex proteins, but most surprisingly, we found that the major viral protein associating with VP16 is the infected cell protein 4 (ICP4) immediate-early (IE) transactivator protein. These results raise the potential for a new function for VP16 in associating with the IE ICP4 and playing a role in transactivation of early and late gene expression, in addition to its well-documented function in transactivation of IE gene expression.
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Affiliation(s)
- Hyung Suk
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - David M Knipe
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
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10
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Vodopiutz J, Schmook MT, Konstantopoulou V, Plecko B, Greber-Platzer S, Creus M, Seidl R, Janecke AR. MED20 mutation associated with infantile basal ganglia degeneration and brain atrophy. Eur J Pediatr 2015; 174:113-8. [PMID: 25446406 DOI: 10.1007/s00431-014-2463-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/15/2014] [Accepted: 11/19/2014] [Indexed: 12/01/2022]
Abstract
UNLABELLED Infantile movement disorders are rare and genetically heterogeneous. We set out to identify the disease-causing mutation in siblings with a novel recessive neurodegenerative movement disorder. Genetic linkage analysis and whole-exome sequencing were performed in the original family. A cohort of six unrelated patients were sequenced for further mutations in the identified candidate gene. Pathogenicity of the mutation was evaluated by in silico analyses and by structural modeling. We identified the first and homozygous mutation (p.Gly114Ala) in the Mediator subunit 20 gene (MED20) in siblings presenting with infantile-onset spasticity and childhood-onset dystonia, progressive basal ganglia degeneration, and brain atrophy. Mediator refers to an evolutionarily conserved multi-subunit RNA polymerase II co-regulatory complex. Pathogenicity of the identified missense mutation is suggested by in silico analyses, by structural modeling, and by previous reporting of mutations in four distinct Mediator subunits causing neurodegenerative phenotypes. No further MED20 mutations were detected in this study. CONCLUSION We delineate a novel infantile-onset neurodegenerative movement disorder and emphasize the Mediator complex as critical for normal neuronal function. Definitive proof of pathogenicity of the identified MED20 mutation will require confirmation in unrelated patients.
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Affiliation(s)
- Julia Vodopiutz
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Wien, Austria,
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11
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Yang C, Hager PW, Stiller JW. The identification of putative RNA polymerase II C-terminal domain associated proteins in red and green algae. Transcription 2014; 5:e970944. [PMID: 25483605 DOI: 10.4161/21541264.2014.970944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A tandemly repeated C-terminal domain (CTD) of the largest subunit of RNA polymerase II is functionally essential and strongly conserved in many organisms, including animal, yeast and plant models. Although present in simple, ancestral red algae, CTD tandem repeats have undergone extensive modifications and degeneration during the evolutionary transition to developmentally complex rhodophytes. In contrast, CTD repeats are conserved in both green algae and their more complex land plant relatives. Understanding the mechanistic differences that underlie these variant patterns of CTD evolution requires knowledge of CTD-associated proteins in these 2 lineages. To provide an initial baseline comparison, we bound potential phospho-CTD associated proteins (PCAPs) to artificially synthesized and phosphorylated CTD repeats from the unicellular red alga Cyanidioschyzon merolae and green alga Chlamydomonas reinhardtii. Our results indicate that red and green algae share a number of PCAPs, including kinases and proteins involved in mRNA export. There also are important taxon-specific differences, including mRNA splicing-related PCAPs recovered from Chlamydomonas but not Cyanidioschyzon, consistent with the relative intron densities in green and red algae. Our results also offer the first experimental indication that different proteins bind 2 distinct types of repeats in Cyanidioschyzon, suggesting a division of function between the proximal and distal CTD, similar to patterns identified in more developmentally complex model organisms.
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Affiliation(s)
- Chunlin Yang
- a Department of Biology ; East Carolina University ; Greenville , NC USA
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12
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The response to inositol: regulation of glycerolipid metabolism and stress response signaling in yeast. Chem Phys Lipids 2014; 180:23-43. [PMID: 24418527 DOI: 10.1016/j.chemphyslip.2013.12.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 12/26/2013] [Indexed: 12/13/2022]
Abstract
This article focuses on discoveries of the mechanisms governing the regulation of glycerolipid metabolism and stress response signaling in response to the phospholipid precursor, inositol. The regulation of glycerolipid lipid metabolism in yeast in response to inositol is highly complex, but increasingly well understood, and the roles of individual lipids in stress response are also increasingly well characterized. Discoveries that have emerged over several decades of genetic, molecular and biochemical analyses of metabolic, regulatory and signaling responses of yeast cells, both mutant and wild type, to the availability of the phospholipid precursor, inositol are discussed.
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13
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Corden JL. RNA polymerase II C-terminal domain: Tethering transcription to transcript and template. Chem Rev 2013; 113:8423-55. [PMID: 24040939 PMCID: PMC3988834 DOI: 10.1021/cr400158h] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jeffry L Corden
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore Maryland 21205, United States
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14
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Abstract
The Mediator complex is a multi-subunit assembly that appears to be required for regulating expression of most RNA polymerase II (pol II) transcripts, which include protein-coding and most non-coding RNA genes. Mediator and pol II function within the pre-initiation complex (PIC), which consists of Mediator, pol II, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH and is approximately 4.0 MDa in size. Mediator serves as a central scaffold within the PIC and helps regulate pol II activity in ways that remain poorly understood. Mediator is also generally targeted by sequence-specific, DNA-binding transcription factors (TFs) that work to control gene expression programs in response to developmental or environmental cues. At a basic level, Mediator functions by relaying signals from TFs directly to the pol II enzyme, thereby facilitating TF-dependent regulation of gene expression. Thus, Mediator is essential for converting biological inputs (communicated by TFs) to physiological responses (via changes in gene expression). In this review, we summarize an expansive body of research on the Mediator complex, with an emphasis on yeast and mammalian complexes. We focus on the basics that underlie Mediator function, such as its structure and subunit composition, and describe its broad regulatory influence on gene expression, ranging from chromatin architecture to transcription initiation and elongation, to mRNA processing. We also describe factors that influence Mediator structure and activity, including TFs, non-coding RNAs and the CDK8 module.
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Affiliation(s)
- Zachary C Poss
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, CO , USA
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15
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HIF1A employs CDK8-mediator to stimulate RNAPII elongation in response to hypoxia. Cell 2013; 153:1327-39. [PMID: 23746844 DOI: 10.1016/j.cell.2013.04.048] [Citation(s) in RCA: 263] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 02/26/2013] [Accepted: 04/25/2013] [Indexed: 01/17/2023]
Abstract
The transcription factor HIF1A is a key mediator of the cellular response to hypoxia. Despite the importance of HIF1A in homeostasis and various pathologies, little is known about how it regulates RNA polymerase II (RNAPII). We report here that HIF1A employs a specific variant of the Mediator complex to stimulate RNAPII elongation. The Mediator-associated kinase CDK8, but not the paralog CDK19, is required for induction of many HIF1A target genes. HIF1A induces binding of CDK8-Mediator and the super elongation complex (SEC), containing AFF4 and CDK9, to alleviate RNAPII pausing. CDK8 is dispensable for HIF1A chromatin binding and histone acetylation, but it is essential for binding of SEC and RNAPII elongation. Global analysis of active RNAPII reveals that hypoxia-inducible genes are paused and active prior to their induction. Our results provide a mechanistic link between HIF1A and CDK8, two potent oncogenes, in the cellular response to hypoxia.
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16
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Ansari SA, Morse RH. Mechanisms of Mediator complex action in transcriptional activation. Cell Mol Life Sci 2013; 70:2743-56. [PMID: 23361037 PMCID: PMC11113466 DOI: 10.1007/s00018-013-1265-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 12/14/2022]
Abstract
Mediator is a large multisubunit complex that plays a central role in the regulation of RNA Pol II transcribed genes. Conserved in overall structure and function among eukaryotes, Mediator comprises 25-30 protein subunits that reside in four distinct modules, termed head, middle, tail, and CDK8/kinase. Different subunits of Mediator contact other transcriptional regulators including activators, co-activators, general transcription factors, subunits of RNA Pol II, and specifically modified histones, leading to the regulated expression of target genes. This review is focused on the interactions of specific Mediator subunits with diverse transcription regulators and how those interactions contribute to Mediator function in transcriptional activation.
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Affiliation(s)
- Suraiya A. Ansari
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201–0509 USA
| | - Randall H. Morse
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201–0509 USA
- Department of Biomedical Science, University at Albany School of Public Health, Albany, NY USA
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17
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Abstract
Gene transcription by RNA polymerase (Pol) II requires the coactivator complex Mediator. Mediator connects transcriptional regulators and Pol II, and is linked to human disease. Mediator from the yeast Saccharomyces cerevisiae has a molecular mass of 1.4 megadaltons and comprises 25 subunits that form the head, middle, tail and kinase modules. The head module constitutes one-half of the essential Mediator core, and comprises the conserved subunits Med6, Med8, Med11, Med17, Med18, Med20 and Med22. Recent X-ray analysis of the S. cerevisiae head module at 4.3 Å resolution led to a partial architectural model with three submodules called neck, fixed jaw and moveable jaw. Here we determine de novo the crystal structure of the head module from the fission yeast Schizosaccharomyces pombe at 3.4 Å resolution. Structure solution was enabled by new structures of Med6 and the fixed jaw, and previous structures of the moveable jaw and part of the neck, and required deletion of Med20. The S. pombe head module resembles the head of a crocodile with eight distinct elements, of which at least four are mobile. The fixed jaw comprises tooth and nose domains, whereas the neck submodule contains a helical spine and one limb, with shoulder, arm and finger elements. The arm and the essential shoulder contact other parts of Mediator. The jaws and a central joint are implicated in interactions with Pol II and its carboxy-terminal domain, and the joint is required for transcription in vitro. The S. pombe head module structure leads to a revised model of the S. cerevisiae module, reveals a high conservation and flexibility, explains known mutations, and provides the basis for unravelling a central mechanism of gene regulation.
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18
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Larivière L, Seizl M, Cramer P. A structural perspective on Mediator function. Curr Opin Cell Biol 2012; 24:305-13. [PMID: 22341791 DOI: 10.1016/j.ceb.2012.01.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/18/2012] [Accepted: 01/22/2012] [Indexed: 11/16/2022]
Abstract
Gene transcription by RNA polymerase II requires the multiprotein coactivator complex Mediator. Mediator was identified two decades ago, but its molecular mechanisms remain poorly understood, because structural studies are hampered by its large size, modularity, and flexibility. Here we collect all available structural data on Mediator and discuss their functional implications. Progress was made in understanding the interactions of Mediator with gene-specific transcriptional regulators and the general transcription machinery. However, around 80% of the Mediator structure remains unknown and details on the Mediator-Pol II interface are lacking. In the future, an integrated structural biology approach may unravel the functional architecture of Mediator-regulated promoter assemblies and holds the promise of understanding a key mechanism of gene regulation.
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Affiliation(s)
- Laurent Larivière
- Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 Munich, Germany
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19
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Conaway RC, Conaway JW. Origins and activity of the Mediator complex. Semin Cell Dev Biol 2011; 22:729-34. [PMID: 21821140 DOI: 10.1016/j.semcdb.2011.07.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 11/16/2022]
Abstract
The Mediator is a large, multisubunit RNA polymerase II transcriptional regulator that was first identified in Saccharomyces cerevisiae as a factor required for responsiveness of Pol II and the general initiation factors to DNA binding transactivators. Since its discovery in yeast, Mediator has been shown to be an integral and highly evolutionarily conserved component of the Pol II transcriptional machinery with critical roles in multiple stages of transcription, from regulation of assembly of the Pol II initiation complex to regulation of Pol II elongation. Here we provide a brief overview of the evolutionary origins of Mediator, its subunit composition, and its remarkably diverse collection of activities in Pol II transcription.
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Affiliation(s)
- Ronald C Conaway
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA.
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20
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Imasaki T, Calero G, Cai G, Tsai KL, Yamada K, Cardelli F, Erdjument-Bromage H, Tempst P, Berger I, Kornberg GL, Asturias FJ, Kornberg RD, Takagi Y. Architecture of the Mediator head module. Nature 2011; 475:240-3. [PMID: 21725323 PMCID: PMC4109712 DOI: 10.1038/nature10162] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 04/28/2011] [Indexed: 01/14/2023]
Abstract
Mediator is a key regulator of eukaryotic transcription, connecting activators and repressors bound to regulatory DNA elements with RNA polymerase II (Pol II). In the yeast Saccharomyces cerevisiae, Mediator comprises 25 subunits with a total mass of more than one megadalton (refs 5, 6) and is organized into three modules, called head, middle/arm and tail. Our understanding of Mediator assembly and its role in regulating transcription has been impeded so far by limited structural information. Here we report the crystal structure of the essential Mediator head module (seven subunits, with a mass of 223 kilodaltons) at a resolution of 4.3 ångströms. Our structure reveals three distinct domains, with the integrity of the complex centred on a bundle of ten helices from five different head subunits. An intricate pattern of interactions within this helical bundle ensures the stable assembly of the head subunits and provides the binding sites for general transcription factors and Pol II. Our structural and functional data suggest that the head module juxtaposes transcription factor IIH and the carboxy-terminal domain of the largest subunit of Pol II, thereby facilitating phosphorylation of the carboxy-terminal domain of Pol II. Our results reveal architectural principles underlying the role of Mediator in the regulation of gene expression.
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Affiliation(s)
- Tsuyoshi Imasaki
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, Indiana 46202
| | - Guillermo Calero
- Department of Structural Biology, Stanford University School of Medicine, Stanford CA 94350
| | - Gang Cai
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla CA 92037
| | - Kuang-Lei Tsai
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla CA 92037
| | - Kentaro Yamada
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, Indiana 46202
| | - Francesco Cardelli
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, Indiana 46202
| | | | - Paul Tempst
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021
| | - Imre Berger
- European Molecular Biology Laboratory (EMBL), Grenoble Outstation, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Guy Lorch Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford CA 94350
| | - Francisco J. Asturias
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla CA 92037
| | - Roger D. Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford CA 94350
| | - Yuichiro Takagi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, Indiana 46202
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21
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Genome-wide screen for inositol auxotrophy in Saccharomyces cerevisiae implicates lipid metabolism in stress response signaling. Mol Genet Genomics 2010; 285:125-49. [PMID: 21136082 DOI: 10.1007/s00438-010-0592-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 11/20/2010] [Indexed: 12/13/2022]
Abstract
Inositol auxotrophy (Ino(-) phenotype) in budding yeast has classically been associated with misregulation of INO1 and other genes involved in lipid metabolism. To identify all non-essential yeast genes that are necessary for growth in the absence of inositol, we carried out a genome-wide phenotypic screening for deletion mutants exhibiting Ino(-) phenotypes under one or more growth conditions. We report the identification of 419 genes, including 385 genes not previously reported, which exhibit this phenotype when deleted. The identified genes are involved in a wide range of cellular processes, but are particularly enriched in those affecting transcription, protein modification, membrane trafficking, diverse stress responses, and lipid metabolism. Among the Ino(-) mutants involved in stress response, many exhibited phenotypes that are strengthened at elevated temperature and/or when choline is present in the medium. The role of inositol in regulation of lipid metabolism and stress response signaling is discussed.
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22
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Larivière L, Seizl M, van Wageningen S, Röther S, van de Pasch L, Feldmann H, Strässer K, Hahn S, Holstege FCP, Cramer P. Structure-system correlation identifies a gene regulatory Mediator submodule. Genes Dev 2008; 22:872-7. [PMID: 18381891 DOI: 10.1101/gad.465108] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A combination of crystallography, biochemistry, and gene expression analysis identifies the coactivator subcomplex Med8C/18/20 as a functionally distinct submodule of the Mediator head module. Med8C forms a conserved alpha-helix that tethers Med18/20 to the Mediator. Deletion of Med8C in vivo results in dissociation of Med18/20 from Mediator and in loss of transcription activity of extracts. Deletion of med8C, med18, or med20 causes similar changes in the yeast transcriptome, establishing Med8C/18/20 as a predominantly positive, gene-specific submodule required for low transcription levels of nonactivated genes, including conjugation genes. The presented structure-based system perturbation is superior to gene deletion analysis of gene regulation.
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Affiliation(s)
- Laurent Larivière
- Gene Center Munich and Center for Integrated Protein Science CIPSM, Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
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23
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He Q, Battistella L, Morse RH. Mediator requirement downstream of chromatin remodeling during transcriptional activation of CHA1 in yeast. J Biol Chem 2007; 283:5276-86. [PMID: 18093974 DOI: 10.1074/jbc.m708266200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mediator complex is essential for transcription by RNA polymerase II in eukaryotes. Although chromatin remodeling is an integral part of transcriptional activation at many promoters, whether Mediator is required for this function has not been determined. Here we have used the yeast CHA1 gene to study the role of Mediator in chromatin remodeling and recruitment of the transcription machinery. We show by chromatin immunoprecipitation that Mediator subunits are recruited to the induced CHA1 promoter. Inactivation of Mediator at 37 degrees C in yeast harboring the srb4-138 (med17) ts mutation severely reduces CHA1 activation and prevents recruitment to the induced CHA1 promoter of Med18/Srb5, from the head module of Mediator, and Med14/Rgr1, which bridges the middle and tail modules. In contrast, recruitment of Med15/Gal11 from the tail module is unaffected in med17 ts yeast at 37 degrees C. Recruitment of TATA-binding protein (TBP) is severely compromised in the absence of functional Mediator, whereas Kin28 and polymerase II recruitment are reduced but to a lesser extent. Induced levels of histone H3K4me3 at the CHA1 promoter are not diminished by inactivation of Mediator, whereas recruitment of Paf1 and of Ser2- and Ser5-phosphorylated forms of Rbp1 are reduced but not eliminated. Loss of histone H3 from the induced CHA1 promoter is seen in wild type yeast but is greatly reduced by loss of intact Mediator. In contrast, Swi/Snf recruitment and nucleosome remodeling are unaffected by loss of Mediator function. Thus, Mediator is required for recruitment of the transcription machinery subsequent to chromatin remodeling during CHA1 induction.
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Affiliation(s)
- Qiye He
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, New York 12201-2002, USA
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24
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Kang ME, Dahmus ME. The unique C-terminal domain of RNA polymerase II and its role in transcription. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 71:41-77. [PMID: 8644491 DOI: 10.1002/9780470123171.ch2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- M E Kang
- Section of Molecular and Cellular Biology, University of California, Davis 95616, USA
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25
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Takagi Y, Calero G, Komori H, Brown JA, Ehrensberger AH, Hudmon A, Asturias F, Kornberg RD. Head module control of mediator interactions. Mol Cell 2006; 23:355-64. [PMID: 16885025 DOI: 10.1016/j.molcel.2006.06.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2006] [Revised: 05/22/2006] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
Yeast Mediator proteins interacting with Med17(Srb4) have been expressed at a high level with the use of recombinant baculoviruses and recovered in homogeneous form as a seven subunit, 223 kDa complex. Electron microscopy and single-particle analysis identify this complex as the Mediator head module. The recombinant head module complements "headless" Mediator for the initiation of transcription in vitro. The module interacts with an RNA polymerase II-TFIIF complex, but not with the polymerase or TFIIF alone. This interaction is lost in the presence of a DNA template and associated RNA transcript, recapitulating the release of Mediator that occurs upon the initiation of transcription. Disruption of the head module in a temperature-sensitive mutant in vivo leads to the release of middle and tail modules from a transcriptionally active promoter. The head module evidently controls Mediator-RNA polymerase II and Mediator-promoter interactions.
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Affiliation(s)
- Yuichiro Takagi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
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26
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Larivière L, Geiger S, Hoeppner S, Röther S, Strässer K, Cramer P. Structure and TBP binding of the Mediator head subcomplex Med8-Med18-Med20. Nat Struct Mol Biol 2006; 13:895-901. [PMID: 16964259 DOI: 10.1038/nsmb1143] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 08/15/2006] [Indexed: 11/09/2022]
Abstract
The Mediator head module stimulates basal RNA polymerase II (Pol II) transcription and enables transcriptional regulation. Here we show that the head subunits Med8, Med18 and Med20 form a subcomplex (Med8/18/20) with two submodules. The highly conserved N-terminal domain of Med8 forms one submodule that binds the TATA box-binding protein (TBP) in vitro and is essential in vivo. The second submodule consists of the C-terminal region of Med8 (Med8C), Med18 and Med20. X-ray analysis of this submodule reveals that Med18 and Med20 form related beta-barrel folds. A conserved putative protein-interaction face on the Med8C/18/20 submodule includes sites altered by srb mutations, which counteract defects resulting from Pol II truncation. Our results and published data support a positive role of the Med8/18/20 subcomplex in initiation-complex formation and suggest that the Mediator head contains a multipartite TBP-binding site that can be modulated by transcriptional activators.
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Affiliation(s)
- Laurent Larivière
- Gene Center Munich, Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
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27
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Baek HJ, Kang YK, Roeder RG. Human Mediator enhances basal transcription by facilitating recruitment of transcription factor IIB during preinitiation complex assembly. J Biol Chem 2006; 281:15172-81. [PMID: 16595664 DOI: 10.1074/jbc.m601983200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The multisubunit Mediator is a well established transcription coactivator for gene-specific activators. However, recent studies have shown that, although not essential for basal transcription by purified RNA polymerase II (pol II) and general initiation factors, Mediator is essential for basal transcription in nuclear extracts that contain a more physiological complement of factors (Mittler, G., Kremmer, E., Timmers, H. T., and Meisterernst, M. (2001) EMBO Rep. 2, 808-813; Baek, H. J., Malik, S., Qin, J., and Roeder, R. G. (2002) Mol. Cell. Biol. 22, 2842-2852). Here, mechanistic studies with immobilized DNA templates, purified factors, and factor-depleted HeLa extracts have shown (i) that Mediator enhancement of basal transcription correlates with Mediator-dependent recruitment of pol II and general initiation factors (transcription factor (TF) IIB and TFIIE) to the promoter; (ii) that Mediator and TFIIB, which both interact with pol II, are jointly required for pol II recruitment to the promoter and that TFIIB recruitment is Mediator-dependent, whereas Mediator recruitment is TFIIB-independent; (iii) that a high level of TFIIB can bypass the Mediator requirement for basal transcription and pol II recruitment in nuclear extract, thus indicating a conditional restriction of TFIIB function and a key role of Mediator in overcoming this restriction; and (iv) that an earlier rate-limiting step involves formation of a TFIID-Mediator-promoter complex. These results support a stepwise assembly model, rather than a preformed holoenzyme model, for Mediator-dependent assembly of a basal preinitiation complex and, more important, identify a step involving TFIIB as a key site of action of Mediator.
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Affiliation(s)
- Hwa Jin Baek
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, New York 10021, USA
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28
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Avendaño A, Riego L, DeLuna A, Aranda C, Romero G, Ishida C, Vázquez-Acevedo M, Rodarte B, Recillas-Targa F, Valenzuela L, Zonszein S, González A. Swi/SNF-GCN5-dependent chromatin remodelling determines induced expression of GDH3, one of the paralogous genes responsible for ammonium assimilation and glutamate biosynthesis in Saccharomyces cerevisiae. Mol Microbiol 2005; 57:291-305. [PMID: 15948967 DOI: 10.1111/j.1365-2958.2005.04689.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
It is accepted that Saccharomyces cerevisiae genome arose from complete duplication of eight ancestral chromosomes; functionally normal ploidy was recovered because of the massive loss of 90% of duplicated genes. There is evidence that indicates that part of this selective conservation of gene pairs is compelling to yeast facultative metabolism. As an example, the duplicated NADP-glutamate dehydrogenase pathway has been maintained because of the differential expression of the paralogous GDH1 and GDH3 genes, and the biochemical specialization of the enzymes they encode. The present work has been aimed to the understanding of the regulatory mechanisms that modulate GDH3 transcriptional activation. Our results show that GDH3 expression is repressed in glucose-grown cultures, as opposed to what has been observed for GDH1, and induced under respiratory conditions, or under stationary phase. Although GDH3 pertains to the nitrogen metabolic network, and its expression is Gln3p-regulated, complete derepression is ultimately determined by the carbon source through the action of the SAGA and SWI/SNF chromatin remodelling complexes. GDH3 carbon-mediated regulation is over-imposed to that exerted by the nitrogen source, highlighting the fact that operation of facultative metabolism requires strict control of enzymes, like Gdh3p, involved in biosynthetic pathways that use tricarboxylic acid cycle intermediates.
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Affiliation(s)
- Amaranta Avendaño
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Mexico City, México
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29
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Nair D, Kim Y, Myers LC. Mediator and TFIIH govern carboxyl-terminal domain-dependent transcription in yeast extracts. J Biol Chem 2005; 280:33739-48. [PMID: 16076843 DOI: 10.1074/jbc.m506067200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Saccharomyces cerevisiae, the RNA polymerase II (RNA Pol II) carboxyl-terminal domain (CTD) is required for viability, and truncation of the CTD results in promoter dependent transcriptional defects. A CTD-less RNA Pol II is unable to support transcription in yeast extracts, but basal transcription reactions reconstituted from highly purified general transcription factors are CTD-independent. To reconcile these two findings, we have taken a biochemical approach using yeast extracts and asked whether there is a factor in the cell that confers CTD-dependence upon transcription. By placing a cleavage site for the tobacco etch virus protease prior to the CTD, we have created a highly specific method for removing the CTD from RNA Pol II in yeast whole cell extracts. Using derivatives of this strain, we have analyzed the role of the Srb8-11 complex, Mediator, and TFIIH, in CTD-dependent basal transcription by either mutation or immunodepletion of their function. We have found that Mediator is a direct intermediary of CTD-dependent basal transcription in extracts and that the requirement for Mediator and the CTD in basal transcription originates from their ability to compensate for a limiting amount of TFIIH activity in extracts.
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Affiliation(s)
- Dhanalakshmi Nair
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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30
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Bourbon HM, Aguilera A, Ansari AZ, Asturias FJ, Berk AJ, Bjorklund S, Blackwell TK, Borggrefe T, Carey M, Carlson M, Conaway JW, Conaway RC, Emmons SW, Fondell JD, Freedman LP, Fukasawa T, Gustafsson CM, Han M, He X, Herman PK, Hinnebusch AG, Holmberg S, Holstege FC, Jaehning JA, Kim YJ, Kuras L, Leutz A, Lis JT, Meisterernest M, Naar AM, Nasmyth K, Parvin JD, Ptashne M, Reinberg D, Ronne H, Sadowski I, Sakurai H, Sipiczki M, Sternberg PW, Stillman DJ, Strich R, Struhl K, Svejstrup JQ, Tuck S, Winston F, Roeder RG, Kornberg RD. A Unified Nomenclature for Protein Subunits of Mediator Complexes Linking Transcriptional Regulators to RNA Polymerase II. Mol Cell 2004; 14:553-7. [PMID: 15175151 DOI: 10.1016/j.molcel.2004.05.011] [Citation(s) in RCA: 218] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Rosonina E, Blencowe BJ. Analysis of the requirement for RNA polymerase II CTD heptapeptide repeats in pre-mRNA splicing and 3'-end cleavage. RNA (NEW YORK, N.Y.) 2004; 10:581-9. [PMID: 15037767 PMCID: PMC1370548 DOI: 10.1261/rna.5207204] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Accepted: 12/18/2003] [Indexed: 05/17/2023]
Abstract
The carboxyl-terminal domain (CTD) of RNA polymerase II (pol II) plays an important role in coupling transcription with precursor messenger RNA (pre-mRNA) processing. Efficient capping, splicing, and 3'-end cleavage of pre-mRNA depend on the CTD. Moreover, specific processing factors are known to associate with this structure. The CTD is therefore thought to act as a platform that facilitates the assembly of complexes required for the processing of nascent transcripts. The mammalian CTD contains 52 tandemly repeated heptapeptides with the consensus sequence YSPTSPS. The C-terminal half of the mammalian CTD contains mostly repeats that diverge from this consensus sequence, whereas the N-terminal half contains mostly repeats that match the consensus sequence. Here, we demonstrate that 22 tandem repeats, from either the conserved or divergent halves of the CTD, are sufficient for approximate wild-type levels of transcription, splicing, and 3'-end cleavage of two different pre-mRNAs, one containing a constitutively spliced intron, and the other containing an intron that depends on an exon enhancer for efficient splicing. In contrast, each block of 22 repeats is not sufficient for efficient inclusion of an alternatively spliced exon in another pre-mRNA. In this case, a longer CTD is important for counteracting the negative effect of a splicing silencer element located within the alternative exon. Our results indicate that the length, rather than the composition of CTD repeats, can be the major determinant in efficient processing of different pre-mRNA substrates. However, the extent of this length requirement depends on specific sequence features within the pre-mRNA substrate.
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Affiliation(s)
- Emanuel Rosonina
- Banting and Best Department of Medical Research, and Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5G 1L6
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32
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Lewis BA, Reinberg D. The mediator coactivator complex: functional and physical roles in transcriptional regulation. J Cell Sci 2003; 116:3667-75. [PMID: 12917354 DOI: 10.1242/jcs.00734] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In vivo, the DNA is packed into chromatin and transcription is dependent upon activators that recruit other factors to reverse the repressive effects of chromatin. The response to activators requires additional factors referred to as coactivators. One such coactivator, mediator, is a multi-subunit complex capable of responding to different activators. It plays an key role in activation, bridging DNA-bound activators, the general transcriptional machinery, especially RNA polymerase II, and the core promoter. Its subunits are necessary for a variety of positive and negative regulatory processes and serve as the direct targets of activators themselves. In vivo and in vitro studies support various roles for mediator in transcription initiation, while structural studies demonstrate that it engages in multiple interactions with RNA polymerase II, and adopts conformations that are activator specific.
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Affiliation(s)
- Brian A Lewis
- Howard Hughes Medical Institute, Division of Nucleic Acids Enzymology, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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33
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Reeves WM, Hahn S. Activator-independent functions of the yeast mediator sin4 complex in preinitiation complex formation and transcription reinitiation. Mol Cell Biol 2003; 23:349-58. [PMID: 12482986 PMCID: PMC140685 DOI: 10.1128/mcb.23.1.349-358.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RNA polymerase II (Pol II) Mediator plays an essential role in both basal and activated transcription. Previously, subunits of the Sin4 Mediator complex (Sin4, Pgd1, Gal11, and Med2) have been implicated in both positive and negative transcriptional regulation. Furthermore, it was proposed that this subcomplex constitutes an activator-binding domain. A yeast nuclear-extract system was used to investigate the biochemical role of the Sin4 complex. In contrast to previous findings, we found at least two general activator-independent roles for the Sin4 complex. First, mutations in sin4 and pgd1 destabilized the Pol II-Med complex, leading to a reduced rate and extent of preinitiation complex (PIC) formation both in the presence and absence of activators. Although reduced in amount compared with the wild type, PICs that are formed lacking the Sin4 complex are stable and can initiate transcription normally. Second, mutation of pgd1 causes partial disruption of the Sin4 complex and leads to a defect in transcription reinitiation. This defect is caused by dissociation of mutant Mediator from promoters after initiation, leading to nonfunctional Scaffold complexes. These results show that function of the Sin4 complex is not essential for transcription activation in a crude in vitro system but that it plays key roles in the general transcription mechanism.
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Affiliation(s)
- Wendy M Reeves
- Molecular and Cellular Biology Program, University of Washington, Seattle 98105, USA
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34
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Jablonowski D, Schaffrath R. Saccharomyces cerevisiae RNA polymerase II is affected by Kluyveromyces lactis zymocin. J Biol Chem 2002; 277:26276-80. [PMID: 12015322 DOI: 10.1074/jbc.m203354200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The G(1) arrest imposed by Kluyveromyces lactis zymocin on Saccharomyces cerevisiae cells requires a functional RNA polymerase II (pol II) Elongator complex. In studying a link between zymocin and pol II, progressively truncating the carboxyl-terminal domain (CTD) of pol II was found to result in zymocin hypersensitivity as did mutations in four different CTD kinase genes. Consistent with the notion that Elongator preferentially associates with hyperphosphorylated (II0) rather than hypophosphorylated (IIA) pol II, the II0/IIA ratio was imbalanced toward II0 on zymocin treatment and suggests zymocin affects pol II function, presumably in an Elongator-dependent manner. As judged from chromatin immunoprecipitations, zymocin-arrested cells were affected with regards to pol II binding to the ADH1 promotor and pol II transcription of the ADH1 gene. Thus, zymocin may interfere with pol II recycling, a scenario assumed to lead to down-regulation of pol II transcription and eventually causing the observed G(1) arrest.
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Affiliation(s)
- Daniel Jablonowski
- Institut für Genetik, Biologicum, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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35
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Riego L, Avendaño A, DeLuna A, Rodríguez E, González A. GDH1 expression is regulated by GLN3, GCN4, and HAP4 under respiratory growth. Biochem Biophys Res Commun 2002; 293:79-85. [PMID: 12054566 DOI: 10.1016/s0006-291x(02)00174-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the yeast Saccharomyces cerevisiae, two NADP(+)-dependent glutamate dehydrogenase isoenzymes encoded by GDH1 and GDH3 catalyze the synthesis of glutamate from ammonium and alpha-ketoglutarate. In this work we analyzed GDH1 transcriptional regulation, in order to deepen the studies in regard to its physiological role. Our results indicate that: (i) GDH1 expression is strictly controlled in ethanol-grown cultures, constituting a fine-tuning mechanism that modulates the abundance of Gdh1p monomers under this condition, (ii) GDH1 expression is controlled by transcriptional activators that have been considered as exclusive of either nitrogen (Gln3p and Gcn4p) or carbon metabolism (HAP complex), and (iii) chromatin remodeling complexes play a role in GDH1 expression; ADA2 and ADA3 up-regulated GDH1 expression on ethanol, while that on glucose was ADA3-dependent. SPT3 and SNF2 activated GDH1 expression on either carbon source whereas GCN5 played no role in any condition tested. The above described combinatorial control results in a refined mechanism that coordinates carbon and nitrogen utilization.
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Affiliation(s)
- Lina Riego
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510 Mexico City, México
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Oelgeschläger T. Regulation of RNA polymerase II activity by CTD phosphorylation and cell cycle control. J Cell Physiol 2002; 190:160-9. [PMID: 11807820 DOI: 10.1002/jcp.10058] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The carboxyl-terminal domain (CTD) of the largest subunit of mammalian RNA polymerase II (RNAP II) consists of 52 repeats of a consensus heptapeptide and is subject to phosphorylation and dephosphorylation events during each round of transcription. RNAP II activity is regulated during the cell cycle and cell cycle-dependend changes in RNAP II activity correlate well with CTD phosphorylation. In addition, global changes in the CTD phosphorylation status are observed in response to mitogenic or cytostatic signals such as growth factors, mitogens and DNA-damaging agents. Several CTD kinases are members of the cyclin-dependent kinase (CDK) superfamily and associate with transcription initiation complexes. Other CTD kinases implicated in cell cycle regulation include the mitogen-activated protein kinases ERK-1/2 and the c-Abl tyrosine kinase. These observations suggest that reversible RNAP II CTD phosphorylation may play a key role in linking cell cycle regulatory events to coordinated changes in transcription.
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Affiliation(s)
- Thomas Oelgeschläger
- Eukaryotic Gene Regulation Laboratory, Marie Curie Research Institute, The Chart, Oxted, Surrey, United Kingdom.
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37
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Kang JS, Kim SH, Hwang MS, Han SJ, Lee YC, Kim YJ. The structural and functional organization of the yeast mediator complex. J Biol Chem 2001; 276:42003-10. [PMID: 11555651 DOI: 10.1074/jbc.m105961200] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Mediator complex of Saccharomyces cerevisiae is required for diverse aspects of transcription by RNA polymerase II (pol II). Mediator is composed of two functionally distinct subcomplexes, Rgr1 and Srb4. To identify the structures and functions of each subcomplex, we expressed recombinant proteins for each subunit and assayed their interactions with each other and with basal transcription proteins. The Rgr1 subcomplex is composed of the Gal11 module, which binds activators, and the Med9/10 module. The Med9/10 module is required for both transcriptional activation and repression, and these activities appear to be carried out by two submodules. Proteins in the Med9 submodule interact physically and genetically with Srb10/11, suggesting that the Med9 submodule mediates the repression of pol II. Purified recombinant Srb4 subcomplex stimulated basal transcription of pol II but had little effect on activated transcription and phosphorylation of the C-terminal domain of the Rpb1 subunit of pol II. Both subcomplexes of Mediator interacted with a distinct set of basal transcription factors and pol II. The modular organization of Mediator and the associated functions suggest that the Mediator complex may recruit and/or stabilize the preinitiation complex through several points of contact with transcriptional regulators and basal transcription factors.
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Affiliation(s)
- J S Kang
- National Creative Research Center for Genome Regulation, Department of Biochemistry, Yonsei University, Seoul 120-749, Korea
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38
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Han SJ, Lee JS, Kang JS, Kim YJ. Med9/Cse2 and Gal11 modules are required for transcriptional repression of distinct group of genes. J Biol Chem 2001; 276:37020-6. [PMID: 11470794 DOI: 10.1074/jbc.m105596200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yeast Mediator is composed of two subcomplexes, Rgr1 and Srb4, known to be required for diverse aspects of transcriptional regulation; however, their structural and functional organizations have not yet been deciphered in detail. Biochemical analyses designed to determine the subunit composition of the Rgr1 subcomplex revealed that the regulator-interacting subcomplex has a modular structure and is composed of the Gal11, Med9/Cse2, and Med10/Nut2 modules. Genome-wide gene expression and Northern analyses performed in the presence or absence of the various Mediator modules revealed a distinct requirement for the Gal11, Med9/Cse2, and Med10/Nut2 modules in transcriptional repression as well as activation. GST pull-down analysis revealed that the transcriptional repressor Tup1 binds to distinct but overlapping regions of the Gal11 module that were shown previously to be transcriptional activator binding sites. These data suggest that competition between transcriptional activators and repressors for a common binding site in the Mediator and distinct conformational changes in the Mediator induced by repressor binding may underlie the mechanism of transcriptional repression in eukaryotes.
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Affiliation(s)
- S J Han
- National Creative Research Initiative Center for Genome Regulation, Department of Biochemistry, 134 Sinchon-dong, Seodaemoon-ku, Yonsei University, Seoul 120-749, Korea
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39
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Ohiso I, Oka M, Nishi N. Theoretical Conformational Analysis of the Tandem Repeat Sequence in RNA Polymerase II. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2001. [DOI: 10.1246/bcsj.74.1847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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40
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Adam M, Robert F, Larochelle M, Gaudreau L. H2A.Z is required for global chromatin integrity and for recruitment of RNA polymerase II under specific conditions. Mol Cell Biol 2001; 21:6270-9. [PMID: 11509669 PMCID: PMC87352 DOI: 10.1128/mcb.21.18.6270-6279.2001] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Evolutionarily conserved variant histone H2A.Z has been recently shown to regulate gene transcription in Saccharomyces cerevisiae. Here we show that loss of H2A.Z in this organism negatively affects the induction of GAL genes. Importantly, fusion of the H2A.Z C-terminal region to S phase H2A without its corresponding C-terminal region can mediate the variant histone's specialized function in GAL1-10 gene induction, and it restores the slow-growth phenotype of cells with a deletion of HTZ1. Furthermore, we show that the C-terminal region of H2A.Z can interact with some components of the transcriptional apparatus. In cells lacking H2A.Z, recruitment of RNA polymerase II and TATA-binding protein to the GAL1-10 promoters is significantly diminished under inducing conditions. Unexpectedly, we also find that H2A.Z is required to globally maintain chromatin integrity under GAL gene-inducing conditions. We hypothesize that H2A.Z can positively regulate gene transcription, at least in part, by modulating interactions with RNA polymerase II-associated factors at certain genes under specific cell growth conditions.
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Affiliation(s)
- M Adam
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
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41
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Ohiso I, Tsunemi M, Zhao B, Nishi N. Conformational Study of the Tandem Repeat Sequence in RNA Polymerase II by Circular Dichroism Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2001. [DOI: 10.1246/bcsj.74.1139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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42
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Balbín M, Fueyo A, Knäuper V, López JM, Alvarez J, Sánchez LM, Quesada V, Bordallo J, Murphy G, López-Otín C. Identification and enzymatic characterization of two diverging murine counterparts of human interstitial collagenase (MMP-1) expressed at sites of embryo implantation. J Biol Chem 2001; 276:10253-62. [PMID: 11113146 DOI: 10.1074/jbc.m009586200] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Remodeling of fibrillar collagen in mouse tissues has been widely attributed to the activity of collagenase-3 (matrix metalloproteinase-13 (MMP-13)), the main collagenase identified in this species. This proposal has been largely based on the repeatedly unproductive attempts to detect the presence in murine tissues of interstitial collagenase (MMP-1), a major collagenase in many species, including humans. In this work, we have performed an extensive screening of murine genomic and cDNA libraries using as probe the full-length cDNA for human MMP-1. We report the identification of two novel members of the MMP gene family which are contained within the cluster of MMP genes located at murine chromosome 9. The isolated cDNAs contain open reading frames of 464 and 463 amino acids and are 82% identical, displaying all structural features characteristic of archetypal MMPs. Comparison for sequence similarities revealed that the highest percentage of identities was found with human interstitial collagenase (MMP-1). The new proteins were tentatively called Mcol-A and Mcol-B (Murine collagenase-like A and B). Analysis of the enzymatic activity of the recombinant proteins revealed that both are catalytically autoactivable but only Mcol-A is able to degrade synthetic peptides and type I and II fibrillar collagen. Both Mcol-A and Mcol-B genes are located in the A1-A2 region of mouse chromosome 9, Mcol-A occupying a position syntenic to the human MMP-1 locus at 11q22. Analysis of the expression of these novel MMPs in murine tissues revealed their predominant presence during mouse embryogenesis, particularly in mouse trophoblast giant cells. According to their structural and functional characteristics, we propose that at least one of these novel members of the MMP family, Mcol-A, may play roles as interstitial collagenase in murine tissues and could represent a true orthologue of human MMP-1.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Chromosome Mapping
- Cloning, Molecular
- Collagen/metabolism
- Collagenases/chemistry
- Collagenases/genetics
- DNA, Complementary/metabolism
- Embryo Implantation
- Embryo, Mammalian/enzymology
- Female
- Gene Expression Regulation, Developmental
- Gene Library
- Genetic Vectors
- Humans
- In Situ Hybridization, Fluorescence
- Matrix Metalloproteinase 1/chemistry
- Matrix Metalloproteinase 9/chemistry
- Matrix Metalloproteinase 9/metabolism
- Matrix Metalloproteinases/chemistry
- Matrix Metalloproteinases/genetics
- Mice
- Models, Molecular
- Molecular Sequence Data
- Multigene Family
- Open Reading Frames
- Phylogeny
- Protein Structure, Tertiary
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Uterus/enzymology
- Uterus/metabolism
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Affiliation(s)
- M Balbín
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología, Universidad de Oviedo, 33006-Oviedo, Spain.
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43
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Abstract
Phosphorylation appears to be one mechanism in the regulation of transcription. Indeed, a multitude of factors involved in distinct steps of transcription, including RNA polymerase II, the general transcription factors, pre-mRNA processing factors, and transcription activators/repressors are phosphoproteins and serve as substrates for multiple kinases. Among these substrates, most attention has been paid in recent years to the phosphorylation of the carboxyl-terminal domain (CTD) of RNA polymerase II and its role in transcription regulation. Kinases responsible for such CTD phosphorylation that are associated with RNA polymerase II at distinct steps of transcription, such as cdk7 and cdk8, also phosphorylate some other components of the transcription machinery in a regulatory manner. These observations enlighten the pivotal role of such kinases in an entangled regulation of transcription by phosphorylation. Summarizing the phosphorylation of various components of the transcription machinery, we point out the variety of steps in transcription that are regulated by such protein modifications, envisioning an interconnection of the several stages of mRNA synthesis by phosphorylation.
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Affiliation(s)
- Thilo Riedl
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, 67404 Illkirch Cedex, France
| | - Jean-Marc Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, 67404 Illkirch Cedex, France
- Address correspondence to Jean Marc Egly, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, 67404 ILLKIRCH Cedex, France. Tel: (33) 3 88 65 34 47; Fax: (33) 3 88 65 32 01; E-mail:
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44
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Feaver WJ, Huang W, Friedberg EC. The TFB4 subunit of yeast TFIIH is required for both nucleotide excision repair and RNA polymerase II transcription. J Biol Chem 1999; 274:29564-7. [PMID: 10506223 DOI: 10.1074/jbc.274.41.29564] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The N-degron strategy has been used to generate a yeast strain harboring a temperature-sensitive allele of TFB4 (tfb4(td)), the gene that encodes the 37-kDa subunit of the transcription/repair factor TFIIH. The tfb4(td) strain was sensitive to UV radiation and is defective in nucleotide excision repair in vitro. The mutant strain was also found to be an inositol auxotroph due at least in part to an inability to properly induce expression of the INO1 gene. These results indicate that like other subunits of TFIIH, Tfb4 is required for both RNA polymerase II transcription and DNA repair.
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Affiliation(s)
- W J Feaver
- Laboratory of Molecular Pathology, Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9072, USA
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45
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Bensaude O, Bonnet F, Cassé C, Dubois MF, Nguyen VT, Palancade B. Regulated phosphorylation of the RNA polymerase II C-terminal domain (CTD). Biochem Cell Biol 1999. [DOI: 10.1139/o99-047] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The largest subunit of RNA polymerase II has an intriguing feature in its carboxyl-terminal domain (CTD) that consists of multiple repeats of an evolutionary conserved motif of seven amino acids. CTD phosphorylation plays a pivotal role in controlling mRNA synthesis and maturation. In exponentially growing cells, the phosphate turnover on the CTD is fast; it is blocked by common inhibitors of transcription, such as 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole and actinomycin D. Transcription-independent changes in CTD phosphorylation are observed at critical developmental stages, such as meiosis and early development.Key words: RNA polymerase II, phosphorylation, transcription inhibitors, cyclin-dependent kinases, development.
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46
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Abstract
A central problem in eukaryotic transcription is how proteins gain access to DNA packaged in nucleosomes. Research on the interplay between chromatin and transcription has progressed with the use of yeast genetics as a useful tool to characterize factors involved in this process. These factors have both positive and negative effects on the stability of nucleosomes, thereby controlling the role of chromatin in transcription in vivo. The negative effectors include the structural components of chromatin, the histones and non-histone chromatin associated proteins, as well as regulatory components like chromatin assembly factors and histone deacetylase complexes. The positive factors are involved in remodeling chromatin and several multiprotein complexes have been described: Swi/Snf, Srb/mediator and SAGA. The components of each of these complexes, as well as the functional relationships between them are covered by this review.
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Affiliation(s)
- J Pérez-Martín
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain.
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47
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Winston F, Sudarsanam P. The SAGA of Spt proteins and transcriptional analysis in yeast: past, present, and future. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 1999; 63:553-61. [PMID: 10384320 DOI: 10.1101/sqb.1998.63.553] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- F Winston
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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48
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Xiao H, Tao Y, Roeder RG. The human homologue of Drosophila TRF-proximal protein is associated with an RNA polymerase II-SRB complex. J Biol Chem 1999; 274:3937-40. [PMID: 9933582 DOI: 10.1074/jbc.274.7.3937] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian RNA polymerase II holoenzymes are large complexes that have been reported to contain, in addition to RNA polymerase II, homologues of several yeast SRBs, various general transcription factors, and other polypeptides. On the basis of its copurification with an SRB-containing RNA polymerase II complex by conventional chromatography procedures, we have identified a human homologue of Drosophila TRF-proximal protein, designated hTRFP, and isolated its cognate cDNA. Antibody specific for SRB7 can immunoprecipitate hTRFP and RNA polymerase II and, reciprocally, antibody specific for hTRFP can immunoprecipitate RNA polymerase II and SRB7. These data indicate that hTRFP is an integral component of an RNA polymerase II-SRB complex. Whereas the precise function of hTRFP remains to be determined, the hTRFP-containing RNA polymerase II-SRB complex supports basal level transcription and, relative to RNA polymerase II alone, enhances transcriptional activation by Gal4-VP16 in the presence of cofactor PC4. Thus, hTRFP may regulate transcription of class II genes through association with the RNA polymerase II-SRB complex.
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Affiliation(s)
- H Xiao
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10021, USA
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49
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Ray A, Ray BK. Isolation and functional characterization of cDNA of serum amyloid A-activating factor that binds to the serum amyloid A promoter. Mol Cell Biol 1998; 18:7327-35. [PMID: 9819419 PMCID: PMC109314 DOI: 10.1128/mcb.18.12.7327] [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] [Received: 10/29/1997] [Accepted: 08/19/1998] [Indexed: 11/20/2022] Open
Abstract
Serum amyloid A (SAA), a plasma protein inducible in response to many inflammatory conditions, is associated with the pathogenesis of several diseases including reactive amyloidosis, rheumatoid arthritis, and atherosclerosis. We have previously reported an element of the SAA promoter, designated SAA-activating sequence (SAS), that is involved in the inflammation-induced SAA expression, and a nuclear factor, SAS-binding factor (SAF), that interacts with the SAS element has been identified previously (A. Ray and B. K. Ray, Mol. Cell. Biol. 16:1584-1594, 1996). To evaluate how SAF is involved in SAA promoter activation, we have investigated structural features and functional characteristics of this transcription factor. Our studies indicate that SAF belongs to a family of transcription factors characterized by the presence of multiple zinc finger motifs of the Cys2-His2 type at the carboxyl end. Of the three cloned SAF cDNAs (SAF-1, SAF-5, and SAF-8), SAF-1 isoform showed a high degree of homology to MAZ/ZF87/Pur-1 protein while SAF-5 and SAF-8 isoforms are unique and are related to SAF-1/MAZ/ZF87/Pur-1 at the zinc finger domains but different elsewhere. Although structurally distinct, all members are capable of activating SAS element-mediated expression and display virtually identical sequence specificities. However, varying levels of expression of members of this gene family were observed in different tissues. Functional activity of SAF is regulated by a posttranslational event as SAF DNA-binding and transactivation abilities are increased by a protein phosphatase inhibitor, okadaic acid, and inhibited by a protein kinase inhibitor, H7. Consistent with this observation, increased DNA binding of the cloned SAF and its hyperphosphorylation, in response to okadaic acid treatment of the transfected cells, were observed. Taken together, our results suggest that, in addition to tissue-specific expression, SAFs, a family of zinc finger transcription factors, undergo a modification by a posttranslational event that confers their SAA promoter-binding activity and transactivation potential.
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Affiliation(s)
- A Ray
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri 65211, USA
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50
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Affiliation(s)
- V E Myer
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142 and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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