101
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Burriss KH, Mosley AL. Methods review: Mass spectrometry analysis of RNAPII complexes. Methods 2019; 159-160:105-114. [PMID: 30902665 DOI: 10.1016/j.ymeth.2019.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/04/2019] [Accepted: 03/17/2019] [Indexed: 12/20/2022] Open
Abstract
RNA Polymerase II (RNAPII) is responsible for transcribing multiple RNA species throughout eukaryotes. A variety of protein-protein interactions occur throughout the transcription cycle for coordinated regulation of transcription initiation, elongation, and/or termination. Taking a proteomics approach to study RNAPII transcription thereby offers a comprehensive view of both RNAPII biology and the variety of proteins that regulate the process itself. This review will focus on how mass spectrometry (MS) methods have expanded understanding of RNAPII and its transcription-regulatory interaction partners. The application of affinity purification mass spectrometry has led to the discovery of a number of novel groups of proteins that regulate an array of RNAPII biology ranging from nuclear import to regulation of phosphorylation state. Additionally, a number of methods have been developed using mass spectrometry to measure protein subunit stoichiometry within and across protein complexes and to perform various types of architectural analysis using structural proteomics approaches. The key methods that we will focus on related to RNAPII mass spectrometry analyses include: affinity purification mass spectrometry, protein post-translational modification analysis, crosslinking mass spectrometry, and native mass spectrometry.
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Affiliation(s)
- Katlyn Hughes Burriss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46402, United States
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46402, United States; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46402, United States.
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102
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Greber BJ, Toso DB, Fang J, Nogales E. The complete structure of the human TFIIH core complex. eLife 2019; 8:e44771. [PMID: 30860024 PMCID: PMC6422496 DOI: 10.7554/elife.44771] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/03/2019] [Indexed: 01/26/2023] Open
Abstract
Transcription factor IIH (TFIIH) is a heterodecameric protein complex critical for transcription initiation by RNA polymerase II and nucleotide excision DNA repair. The TFIIH core complex is sufficient for its repair functions and harbors the XPB and XPD DNA-dependent ATPase/helicase subunits, which are affected by human disease mutations. Transcription initiation additionally requires the CdK activating kinase subcomplex. Previous structural work has provided only partial insight into the architecture of TFIIH and its interactions within transcription pre-initiation complexes. Here, we present the complete structure of the human TFIIH core complex, determined by phase-plate cryo-electron microscopy at 3.7 Å resolution. The structure uncovers the molecular basis of TFIIH assembly, revealing how the recruitment of XPB by p52 depends on a pseudo-symmetric dimer of homologous domains in these two proteins. The structure also suggests a function for p62 in the regulation of XPD, and allows the mapping of previously unresolved human disease mutations.
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Affiliation(s)
- Basil J Greber
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
- Molecular Biophysics and Integrative Bio-Imaging DivisionLawrence Berkeley National LaboratoryBerkeleyUnited States
| | - Daniel B Toso
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
| | - Jie Fang
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
| | - Eva Nogales
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
- Molecular Biophysics and Integrative Bio-Imaging DivisionLawrence Berkeley National LaboratoryBerkeleyUnited States
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
- Department of Molecular and Cell BiologyUniversity of CaliforniaBerkeleyUnited States
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103
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Braitbard M, Schneidman-Duhovny D, Kalisman N. Integrative Structure Modeling: Overview and Assessment. Annu Rev Biochem 2019; 88:113-135. [PMID: 30830798 DOI: 10.1146/annurev-biochem-013118-111429] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Integrative structure modeling computationally combines data from multiple sources of information with the aim of obtaining structural insights that are not revealed by any single approach alone. In the first part of this review, we survey the commonly used sources of structural information and the computational aspects of model building. Throughout the past decade, integrative modeling was applied to various biological systems, with a focus on large protein complexes. Recent progress in the field of cryo-electron microscopy (cryo-EM) has resolved many of these complexes to near-atomic resolution. In the second part of this review, we compare a range of published integrative models with their higher-resolution counterparts with the aim of critically assessing their accuracy. This comparison gives a favorable view of integrative modeling and demonstrates its ability to yield accurate and informative results. We discuss possible roles of integrative modeling in the new era of cryo-EM and highlight future challenges and directions.
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Affiliation(s)
- Merav Braitbard
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel;
| | - Dina Schneidman-Duhovny
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; .,School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel;
| | - Nir Kalisman
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel;
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104
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Twenty years of Mediator complex structural studies. Biochem Soc Trans 2019; 47:399-410. [PMID: 30733343 PMCID: PMC6393861 DOI: 10.1042/bst20180608] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/14/2019] [Accepted: 01/16/2019] [Indexed: 11/18/2022]
Abstract
Mediator is a large multiprotein complex conserved in all eukaryotes that plays an essential role in transcriptional regulation. Mediator comprises 25 subunits in yeast and 30 subunits in humans that form three main modules and a separable four-subunit kinase module. For nearly 20 years, because of its size and complexity, Mediator has posed a formidable challenge to structural biologists. The first two-dimensional electron microscopy (EM) projection map of Mediator leading to the canonical view of its division in three topological modules named Head, Middle and Tail, was published in 1999. Within the last few years, optimization of Mediator purification combined with technical and methodological advances in cryo-electron microscopy (cryo-EM) have revealed unprecedented details of Mediator subunit organization, interactions with RNA polymerase II and parts of its core structure at high resolution. To celebrate the twentieth anniversary of the first Mediator EM reconstruction, we look back on the structural studies of Mediator complex from a historical perspective and discuss them in the light of our current understanding of its role in transcriptional regulation.
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105
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Rose AB. Introns as Gene Regulators: A Brick on the Accelerator. Front Genet 2019; 9:672. [PMID: 30792737 PMCID: PMC6374622 DOI: 10.3389/fgene.2018.00672] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/04/2018] [Indexed: 01/25/2023] Open
Abstract
A picture is beginning to emerge from a variety of organisms that for a subset of genes, the most important sequences that regulate expression are situated not in the promoter but rather are located within introns in the first kilobase of transcribed sequences. The actual sequences involved are difficult to identify either by sequence comparisons or by deletion analysis because they are dispersed, additive, and poorly conserved. However, expression-controlling introns can be identified computationally in species with relatively small introns, based on genome-wide differences in oligomer composition between promoter-proximal and distal introns. The genes regulated by introns are often expressed in most tissues and are among the most highly expressed in the genome. The ability of some introns to strongly stimulate mRNA accumulation from several hundred nucleotides downstream of the transcription start site, even when the promoter has been deleted, reveals that our understanding of gene expression remains incomplete. It is unlikely that any diseases are caused by point mutations or small deletions that reduce the expression of an intron-regulated gene unless splicing is also affected. However, introns may be particularly useful in practical applications such as gene therapy because they strongly activate expression but only affect the transcription unit in which they are located.
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Affiliation(s)
- Alan B Rose
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
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106
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Petrenko N, Jin Y, Dong L, Wong KH, Struhl K. Requirements for RNA polymerase II preinitiation complex formation in vivo. eLife 2019; 8:43654. [PMID: 30681409 PMCID: PMC6366898 DOI: 10.7554/elife.43654] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/25/2019] [Indexed: 01/26/2023] Open
Abstract
Transcription by RNA polymerase II requires assembly of a preinitiation complex (PIC) composed of general transcription factors (GTFs) bound at the promoter. In vitro, some GTFs are essential for transcription, whereas others are not required under certain conditions. PICs are stable in the absence of nucleotide triphosphates, and subsets of GTFs can form partial PICs. By depleting individual GTFs in yeast cells, we show that all GTFs are essential for TBP binding and transcription, suggesting that partial PICs do not exist at appreciable levels in vivo. Depletion of FACT, a histone chaperone that travels with elongating Pol II, strongly reduces PIC formation and transcription. In contrast, TBP-associated factors (TAFs) contribute to transcription of most genes, but TAF-independent transcription occurs at substantial levels, preferentially at promoters containing TATA elements. PICs are absent in cells deprived of uracil, and presumably UTP, suggesting that transcriptionally inactive PICs are removed from promoters in vivo.
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Affiliation(s)
- Natalia Petrenko
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Yi Jin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Liguo Dong
- Faculty of Health Sciences, University of Macau, Macau, China
| | - Koon Ho Wong
- Institute of Translational Medicine, University of Macau, Macau, China
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
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107
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Kaur U, Johnson DT, Chea EE, Deredge DJ, Espino JA, Jones LM. Evolution of Structural Biology through the Lens of Mass Spectrometry. Anal Chem 2019; 91:142-155. [PMID: 30457831 PMCID: PMC6472977 DOI: 10.1021/acs.analchem.8b05014] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Upneet Kaur
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Danté T. Johnson
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Emily E. Chea
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Daniel J. Deredge
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Jessica A. Espino
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Lisa M. Jones
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
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108
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Kaur U, Johnson DT, Chea EE, Deredge DJ, Espino JA, Jones LM. Evolution of Structural Biology through the Lens of Mass Spectrometry. Anal Chem 2019; 91:142-155. [PMID: 30457831 DOI: 10.1021/acs.analchem.1028b05014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Upneet Kaur
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Danté T Johnson
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Emily E Chea
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Daniel J Deredge
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Jessica A Espino
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Lisa M Jones
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
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109
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Greber BJ, Nogales E. The Structures of Eukaryotic Transcription Pre-initiation Complexes and Their Functional Implications. Subcell Biochem 2019; 93:143-192. [PMID: 31939151 DOI: 10.1007/978-3-030-28151-9_5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcription is a highly regulated process that supplies living cells with coding and non-coding RNA molecules. Failure to properly regulate transcription is associated with human pathologies, including cancers. RNA polymerase II is the enzyme complex that synthesizes messenger RNAs that are then translated into proteins. In spite of its complexity, RNA polymerase requires a plethora of general transcription factors to be recruited to the transcription start site as part of a large transcription pre-initiation complex, and to help it gain access to the transcribed strand of the DNA. This chapter reviews the structure and function of these eukaryotic transcription pre-initiation complexes, with a particular emphasis on two of its constituents, the multisubunit complexes TFIID and TFIIH. We also compare the overall architecture of the RNA polymerase II pre-initiation complex with those of RNA polymerases I and III, involved in transcription of ribosomal RNA and non-coding RNAs such as tRNAs and snRNAs, and discuss the general, conserved features that are applicable to all eukaryotic RNA polymerase systems.
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Affiliation(s)
- Basil J Greber
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, 94720, USA.
- Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Eva Nogales
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, 94720, USA
- Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
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110
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Tourigny JP, Saleh MM, Schumacher K, Devys D, Zentner GE. Mediator Is Essential for Small Nuclear and Nucleolar RNA Transcription in Yeast. Mol Cell Biol 2018; 38:e00296-18. [PMID: 30275344 PMCID: PMC6275182 DOI: 10.1128/mcb.00296-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/13/2018] [Accepted: 09/21/2018] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic RNA polymerase II (RNAPII) transcribes mRNA genes and non-protein-coding RNA (ncRNA) genes, including those encoding small nuclear and nucleolar RNAs (sn/snoRNAs). In metazoans, RNAPII transcription of sn/snoRNAs is facilitated by a number of specialized complexes, but no such complexes have been discovered in yeast. It has been proposed that yeast sn/snoRNA and mRNA expression relies on a set of common factors, but the extent to which regulators of mRNA genes function at yeast sn/snoRNA genes is unclear. Here, we investigated a potential role for the Mediator complex, essential for mRNA gene transcription, in sn/snoRNA gene transcription. We found that Mediator maps to sn/snoRNA gene regulatory regions and that rapid depletion of the essential structural subunit Med14 strongly reduces RNAPII and TFIIB occupancy as well as nascent transcription of sn/snoRNA genes. Deletion of Med3 and Med15, subunits of the activator-interacting Mediator tail module, does not affect Mediator recruitment to or RNAPII and TFIIB occupancy of sn/snoRNA genes. Our analyses suggest that Mediator promotes PIC formation and transcription at sn/snoRNA genes, expanding the role of this critical regulator beyond its known functions in mRNA gene transcription and demonstrating further mechanistic similarity between the transcription of mRNA and sn/snoRNA genes.
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Affiliation(s)
- Jason P Tourigny
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Moustafa M Saleh
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Kenny Schumacher
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Didier Devys
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, Illkirch, France
- Université de Strasbourg, Illkirch, France
| | - Gabriel E Zentner
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, Indiana, USA
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111
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Knoll ER, Zhu ZI, Sarkar D, Landsman D, Morse RH. Role of the pre-initiation complex in Mediator recruitment and dynamics. eLife 2018; 7:39633. [PMID: 30540252 PMCID: PMC6322861 DOI: 10.7554/elife.39633] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 12/12/2018] [Indexed: 12/19/2022] Open
Abstract
The Mediator complex stimulates the cooperative assembly of a pre-initiation complex (PIC) and recruitment of RNA Polymerase II (Pol II) for gene activation. The core Mediator complex is organized into head, middle, and tail modules, and in budding yeast (Saccharomyces cerevisiae), Mediator recruitment has generally been ascribed to sequence-specific activators engaging the tail module triad of Med2-Med3-Med15 at upstream activating sequences (UASs). We show that yeast lacking Med2-Med3-Med15 are viable and that Mediator and PolII are recruited to promoters genome-wide in these cells, albeit at reduced levels. To test whether Mediator might alternatively be recruited via interactions with the PIC, we examined Mediator association genome-wide after depleting PIC components. We found that depletion of Taf1, Rpb3, and TBP profoundly affected Mediator association at active gene promoters, with TBP being critical for transit of Mediator from UAS to promoter, while Pol II and Taf1 stabilize Mediator association at proximal promoters.
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Affiliation(s)
- Elisabeth R Knoll
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, United States
| | - Z Iris Zhu
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, Bethesda, United States
| | - Debasish Sarkar
- Wadsworth Center, New York State Department of Health, Albany, United States
| | - David Landsman
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, Bethesda, United States
| | - Randall H Morse
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, United States.,Wadsworth Center, New York State Department of Health, Albany, United States
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112
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Thompson VF, Victor RA, Morera AA, Moinpour M, Liu MN, Kisiel CC, Pickrel K, Springhower CE, Schwartz JC. Transcription-Dependent Formation of Nuclear Granules Containing FUS and RNA Pol II. Biochemistry 2018; 57:7021-7032. [PMID: 30488693 DOI: 10.1021/acs.biochem.8b01097] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Purified recombinant FUsed in Sarcoma (FUS) assembles into an oligomeric state in an RNA-dependent manner to form large condensates. FUS condensates bind and concentrate the C-terminal domain of RNA polymerase II (RNA Pol II). We asked whether a granule in cells contained FUS and RNA Pol II as suggested by the binding of FUS condensates to the polymerase. We developed cross-linking protocols to recover protein particles containing FUS from cells and separated them by size exclusion chromatography. We found a significant fraction of RNA Pol II in large granules containing FUS with diameters of >50 nm or twice that of the RNA Pol II holoenzyme. Inhibition of transcription prevented the polymerase from associating with the granules. Altogether, we found physical evidence of granules containing FUS and RNA Pol II in cells that possess properties comparable to those of in vitro FUS condensates.
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113
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Kim JM, Seok OH, Ju S, Heo JE, Yeom J, Kim DS, Yoo JY, Varshavsky A, Lee C, Hwang CS. Formyl-methionine as an N-degron of a eukaryotic N-end rule pathway. Science 2018; 362:science.aat0174. [PMID: 30409808 DOI: 10.1126/science.aat0174] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 08/24/2018] [Accepted: 10/24/2018] [Indexed: 12/17/2022]
Abstract
In bacteria, nascent proteins bear the pretranslationally generated N-terminal (Nt) formyl-methionine (fMet) residue. Nt-fMet of bacterial proteins is a degradation signal, termed fMet/N-degron. By contrast, proteins synthesized by cytosolic ribosomes of eukaryotes were presumed to bear unformylated Nt-Met. Here we found that the yeast formyltransferase Fmt1, although imported into mitochondria, could also produce Nt-formylated proteins in the cytosol. Nt-formylated proteins were strongly up-regulated in stationary phase or upon starvation for specific amino acids. This up-regulation strictly required the Gcn2 kinase, which phosphorylates Fmt1 and mediates its retention in the cytosol. We also found that the Nt-fMet residues of Nt-formylated proteins act as fMet/N-degrons and identified the Psh1 ubiquitin ligase as the recognition component of the eukaryotic fMet/N-end rule pathway, which destroys Nt-formylated proteins.
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Affiliation(s)
- Jeong-Mok Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Ok-Hee Seok
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Shinyeong Ju
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea.,Department of Life Science and Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Ji-Eun Heo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Jeonghun Yeom
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Republic of Korea
| | - Da-Som Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Joo-Yeon Yoo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Alexander Varshavsky
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Cheolju Lee
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea. .,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Republic of Korea.,Department of Converging Science and Technology, KHU-KIST, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Cheol-Sang Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea.
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114
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Sierecki E. The Mediator complex and the role of protein-protein interactions in the gene regulation machinery. Semin Cell Dev Biol 2018; 99:20-30. [PMID: 30278226 DOI: 10.1016/j.semcdb.2018.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/13/2018] [Accepted: 08/13/2018] [Indexed: 12/11/2022]
Abstract
At the core of gene regulation, a complex network of dynamic interactions between proteins, DNA and RNA has to be integrated in order to generate a binary biological output. Large protein complexes, called adaptors, transfer information from the transcription factors to the transcription machinery [1,2]. Here we focus on Mediator, one of the largest adaptor proteins in humans [3]. Assembled from 30 different subunits, this system provides extraordinary illustrations for the various roles played by protein-protein interactions. Recruitment of new subunits during evolution is an adaptive mechanism to the growing complexity of the organism. Integration of information happens at multiple scales, with allosteric effects at the level of individual subunits resulting in large conformational changes. Mediator is also rich in disordered regions that increase the potential for interactions by presenting a malleable surface to its environment. Potentially, 3000 transcription factors can interact with Mediator and so understanding the molecular mechanisms that support the processing of this overload of information is one of the great challenges in molecular biology.
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Affiliation(s)
- Emma Sierecki
- EMBL Australia Node in Single Molecule Science, and School of Medical Sciences, Faculty of Medecine, The University of New South Wales, Sydney, Australia.
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115
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Hanske J, Sadian Y, Müller CW. The cryo-EM resolution revolution and transcription complexes. Curr Opin Struct Biol 2018; 52:8-15. [PMID: 30015202 PMCID: PMC6302067 DOI: 10.1016/j.sbi.2018.07.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 06/25/2018] [Accepted: 07/02/2018] [Indexed: 01/22/2023]
Abstract
Direct electron detector technology combined with improved imaging processing procedures has dramatically increased the resolution that can be obtained by single-particle cryo-electron microscopy and cryo-electron tomography. These developments-often referred to as the `resolution revolution' in cryo-EM-have had a profound impact on the structural biology of transcription as they allow the determination of atomic or near-atomic resolution structures of very large, flexible and often transient transcription complexes that in many cases had resisted crystal structure determination for decades. In this review, we will discuss recent advances and breakthroughs in the structural biology of transcription complexes enabled by the revolution in cryo-electron microscopy with particular focus on eukaryotic RNA polymerases and their pre-initiation complexes, but also chromatin remodelers and epigenetic regulators.
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Affiliation(s)
- Jonas Hanske
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Yashar Sadian
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Christoph W Müller
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany.
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116
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Jishage M, Yu X, Shi Y, Ganesan SJ, Chen WY, Sali A, Chait BT, Asturias FJ, Roeder RG. Architecture of Pol II(G) and molecular mechanism of transcription regulation by Gdown1. Nat Struct Mol Biol 2018; 25:859-867. [PMID: 30190596 PMCID: PMC6298426 DOI: 10.1038/s41594-018-0118-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 07/24/2018] [Indexed: 12/19/2022]
Abstract
Tight binding of Gdown1 represses RNA polymerase II (Pol II) function in a manner that is reversed by Mediator, but the structural basis of these processes is unclear. Although Gdown1 is intrinsically disordered, its Pol II interacting domains were localized and shown to occlude transcription factor IIF (TFIIF) and transcription factor IIB (TFIIB) binding by perfect positioning on their Pol II interaction sites. Robust binding of Gdown1 to Pol II is established by cooperative interactions of a strong Pol II binding region and two weaker binding modulatory regions, thus providing a mechanism both for tight Pol II binding and transcription inhibition and for its reversal. In support of a physiological function for Gdown1 in transcription repression, Gdown1 co-localizes with Pol II in transcriptionally silent nuclei of early Drosophila embryos but re-localizes to the cytoplasm during zygotic genome activation. Our study reveals a self-inactivation through Gdown1 binding as a unique mode of repression in Pol II function.
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Affiliation(s)
- Miki Jishage
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Xiaodi Yu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, San Diego, CA, USA
- Pfizer Inc., Groton, CT, USA
| | - Yi Shi
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sai J Ganesan
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Wei-Yi Chen
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY, USA
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
| | - Francisco J Asturias
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, San Diego, CA, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY, USA.
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117
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Chavez JD, Bruce JE. Chemical cross-linking with mass spectrometry: a tool for systems structural biology. Curr Opin Chem Biol 2018; 48:8-18. [PMID: 30172868 DOI: 10.1016/j.cbpa.2018.08.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/09/2018] [Accepted: 08/10/2018] [Indexed: 01/14/2023]
Abstract
Biological processes supporting life are orchestrated by a highly dynamic array of protein structures and interactions comprising the interactome. Defining the interactome, visualizing how structures and interactions change and function to support life is essential to improved understanding of fundamental molecular processes, but represents a challenge unmet by any single analytical technique. Chemical cross-linking with mass spectrometry provides identification of proximal amino acid residues within proteins and protein complexes, yielding low resolution structural information. This approach has predominantly been employed to provide structural insight on isolated protein complexes, and has been particularly useful for molecules that are recalcitrant to conventional structural biology studies. Here we discuss recent developments in cross-linking and mass spectrometry technologies that are providing large-scale or systems-level interactome data with successful applications to isolated organelles, cell lysates, virus particles, intact bacterial and mammalian cultured cells and tissue samples.
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Affiliation(s)
- Juan D Chavez
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - James E Bruce
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA 98195, USA.
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118
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Monté D, Clantin B, Dewitte F, Lens Z, Rucktooa P, Pardon E, Steyaert J, Verger A, Villeret V. Crystal structure of human Mediator subunit MED23. Nat Commun 2018; 9:3389. [PMID: 30140054 PMCID: PMC6107663 DOI: 10.1038/s41467-018-05967-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/01/2018] [Indexed: 11/18/2022] Open
Abstract
The Mediator complex transduces regulatory information from enhancers to promoters and performs essential roles in the initiation of transcription in eukaryotes. Human Mediator comprises 26 subunits forming three modules termed Head, Middle and Tail. Here we present the 2.8 Å crystal structure of MED23, the largest subunit from the human Tail module. The structure identifies 25 HEAT repeats-like motifs organized into 5 α-solenoids. MED23 adopts an arch-shaped conformation, with an N-terminal domain (Nter) protruding from a large core region. In the core four solenoids, motifs wrap on themselves, creating triangular-shaped structural motifs on both faces of the arch, with extended grooves propagating through the interfaces between the solenoid motifs. MED23 is known to interact with several specific transcription activators and is involved in splicing, elongation, and post-transcriptional events. The structure rationalizes previous biochemical observations and paves the way for improved understanding of the cross-talk between Mediator and transcriptional activators. Mediator is a large multi-subunits complex essential to the regulation of transcription by RNA pol II. Here the authors report the crystal structure of MED23—one of the largest subunits of the complex together with MED1 and MED14—revealing a complex architecture and filling an important gap in the structural characterization of Mediator.
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Affiliation(s)
- Didier Monté
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France.
| | - Bernard Clantin
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France
| | - Frédérique Dewitte
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France
| | - Zoé Lens
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France
| | - Prakash Rucktooa
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France.,Heptares Therapeutics Ltd., Broadwater Road, Hertfordshire, AL7 3AX, UK
| | - Els Pardon
- VIB-VUB Center for Structural Biology, Pleinlaan 2, 1050, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Jan Steyaert
- VIB-VUB Center for Structural Biology, Pleinlaan 2, 1050, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Alexis Verger
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France
| | - Vincent Villeret
- CNRS, UMR 8576-UGSF- Unité de Glycobiologie Structurale et Fonctionnelle, Univ. Lille, 59000, Lille, France.
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119
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Liu S, Yu F, Hu Q, Wang T, Yu L, Du S, Yu W, Li N. Development of in Planta Chemical Cross-Linking-Based Quantitative Interactomics in Arabidopsis. J Proteome Res 2018; 17:3195-3213. [DOI: 10.1021/acs.jproteome.8b00320] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Shichang Liu
- Division of Life Science, Energy Institute, Institute for the Environment, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Fengchao Yu
- Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Qin Hu
- Division of Life Science, Energy Institute, Institute for the Environment, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Tingliang Wang
- Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lujia Yu
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Shengwang Du
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Weichuan Yu
- Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Ning Li
- Division of Life Science, Energy Institute, Institute for the Environment, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- The Hong Kong University of Science and Technology, Shenzhen Research Institute, Shenzhen Guangdong 518057, China
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120
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Mediator, known as a coactivator, can act in transcription initiation in an activator-independent manner in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:687-696. [DOI: 10.1016/j.bbagrm.2018.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/28/2018] [Accepted: 07/04/2018] [Indexed: 01/20/2023]
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121
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Smith DL, Götze M, Bartolec TK, Hart-Smith G, Wilkins MR. Characterization of the Interaction between Arginine Methyltransferase Hmt1 and Its Substrate Npl3: Use of Multiple Cross-Linkers, Mass Spectrometric Approaches, and Software Platforms. Anal Chem 2018; 90:9101-9108. [PMID: 30004689 DOI: 10.1021/acs.analchem.8b01525] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study investigated the enzyme-substrate interaction between Saccharomyces cerevisiae arginine methyltransferase Hmt1p and nucleolar protein Npl3p, using chemical cross linking/mass spectrometry (XL/MS). We show that XL/MS can capture transient interprotein interactions that occur during the process of methylation, involving a disordered region in Npl3p with tandem SRGG repeats, and we confirm that Hmt1p and Npl3p exist as homomultimers. Additionally, the study investigated the interdependencies between variables of an XL/MS experiment that lead to the identification of identical or different cross-linked peptides. We report that there are substantial benefits, in terms of biologically relevant cross-links identified, that result from the use of two mass-spectrometry-cleavable cross-linkers [disuccinimido sulfoxide (DSSO) and disuccinimido dibutyric urea (DSBU)], two fragmentation approaches [collision-induced dissociation and electron-transfer dissociation (CID+ETD)] and stepped high-energy collision dissociation (HCD)], and two programs (MeroX and XlinkX). We also show that there are specific combinations of XL/MS methods that are more successful than others for the two proteins investigated here; these are explored in detail in the text. Data are available via ProteomeXchange with identifier PXD008348.
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Affiliation(s)
- Daniela-Lee Smith
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney , New South Wales 2052 , Australia
| | - Michael Götze
- Institute of Biochemistry , Martin Luther University Halle-Wittenberg , Kurt-Mothes-Strasse 3 , D-06120 Halle (Saale) , Germany
| | - Tara K Bartolec
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney , New South Wales 2052 , Australia
| | - Gene Hart-Smith
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney , New South Wales 2052 , Australia
| | - Marc R Wilkins
- Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences , University of New South Wales , Sydney , New South Wales 2052 , Australia
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122
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Postrecruitment Function of Yeast Med6 Protein during the Transcriptional Activation by Mediator Complex. Biochem Res Int 2018; 2018:6406372. [PMID: 29992056 PMCID: PMC5818915 DOI: 10.1155/2018/6406372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/29/2017] [Indexed: 11/17/2022] Open
Abstract
Med6 protein (Med6p) is a hallmark component of evolutionarily conserved Mediator complexes, and the genuine role of Med6p in Mediator functions remains elusive. For the functional analysis of Saccharomyces cerevisiae Med6p (scMed6p), we generated a series of scMed6p mutants harboring a small internal deletion. Genetic analysis of these mutants revealed that three regions (amino acids 33-42 (Δ2), 125-134 (Δ5), and 157-166 (Δ6)) of scMed6p are required for cell viability and are located at highly conserved regions of Med6 homologs. Notably, the Med6p-Δ2 mutant was barely detectable in whole-cell extracts and purified Mediator, suggesting a loss of Mediator association and concurrent rapid degradation. Consistent with this, the recombinant forms of Med6p having these mutations partially (Δ2) restore or fail (Δ5 and Δ6) to restore in vitro transcriptional defects caused by temperature-sensitive med6 mutation. In an artificial recruitment assay, Mediator containing a LexA-fused wild-type Med6p or Med6p-Δ5 was recruited to the lexA operator region with TBP and activated reporter gene expression. However, the recruitment of Mediator containing LexA-Med6p-Δ6 to lexA operator region resulted in neither TBP recruitment nor reporter gene expression. This result demonstrates a pivotal role of Med6p in the postrecruitment function of Mediator, which is essential for transcriptional activation by Mediator.
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123
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Cho WK, Spille JH, Hecht M, Lee C, Li C, Grube V, Cisse II. Mediator and RNA polymerase II clusters associate in transcription-dependent condensates. Science 2018; 361:412-415. [PMID: 29930094 DOI: 10.1126/science.aar4199] [Citation(s) in RCA: 812] [Impact Index Per Article: 135.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 04/17/2018] [Accepted: 06/11/2018] [Indexed: 12/20/2022]
Abstract
Models of gene control have emerged from genetic and biochemical studies, with limited consideration of the spatial organization and dynamics of key components in living cells. We used live-cell superresolution and light-sheet imaging to study the organization and dynamics of the Mediator coactivator and RNA polymerase II (Pol II) directly. Mediator and Pol II each form small transient and large stable clusters in living embryonic stem cells. Mediator and Pol II are colocalized in the stable clusters, which associate with chromatin, have properties of phase-separated condensates, and are sensitive to transcriptional inhibitors. We suggest that large clusters of Mediator, recruited by transcription factors at large or clustered enhancer elements, interact with large Pol II clusters in transcriptional condensates in vivo.
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Affiliation(s)
- Won-Ki Cho
- Department of Physics, MIT, Cambridge, MA 02139, USA
| | | | - Micca Hecht
- Department of Physics, MIT, Cambridge, MA 02139, USA
| | - Choongman Lee
- Department of Physics, MIT, Cambridge, MA 02139, USA
| | - Charles Li
- Department of Biology, MIT, Cambridge, MA 02139, USA.,Whitehead Institute for Biomedical Research, Cambridge, MA 02139, USA
| | - Valentin Grube
- Department of Physics, MIT, Cambridge, MA 02139, USA.,Department of Physics, LMU Munich, Geschwister Scholl Platz 1, 80539 Munich, Germany
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124
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Putlyaev EV, Ibragimov AN, Lebedeva LA, Georgiev PG, Shidlovskii YV. Structure and Functions of the Mediator Complex. BIOCHEMISTRY (MOSCOW) 2018; 83:423-436. [PMID: 29626929 DOI: 10.1134/s0006297918040132] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mediator is a key factor in the regulation of expression of RNA polymerase II-transcribed genes. Recent studies have shown that Mediator acts as a coordinator of transcription activation and participates in maintaining chromatin architecture in the cell nucleus. In this review, we present current concepts on the structure and functions of Mediator.
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Affiliation(s)
- E V Putlyaev
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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125
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Chu F, Thornton DT, Nguyen HT. Chemical cross-linking in the structural analysis of protein assemblies. Methods 2018; 144:53-63. [PMID: 29857191 DOI: 10.1016/j.ymeth.2018.05.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/22/2018] [Accepted: 05/25/2018] [Indexed: 12/31/2022] Open
Abstract
For decades, chemical cross-linking of proteins has been an established method to study protein interaction partners. The chemical cross-linking approach has recently been revived by mass spectrometric analysis of the cross-linking reaction products. Chemical cross-linking and mass spectrometric analysis (CXMS) enables the identification of residues that are close in three-dimensional (3D) space but not necessarily close in primary sequence. Therefore, this approach provides medium resolution information to guide de novo structure prediction, protein interface mapping and protein complex model building. The robustness and compatibility of the CXMS approach with multiple biochemical methods have made it especially appealing for challenging systems with multiple biochemical compositions and conformation states. This review provides an overview of the CXMS approach, describing general procedures in sample processing, data acquisition and analysis. Selection of proper chemical cross-linking reagents, strategies for cross-linked peptide identification, and successful application of CXMS in structural characterization of proteins and protein complexes are discussed.
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Affiliation(s)
- Feixia Chu
- Department of Molecular, Cellular & Biomedical Sciences, University of New Hampshire, Durham, NH 03824, United States; Hubbard Center for Genome Studies, University of New Hampshire, Durham, NH 03824, United States.
| | - Daniel T Thornton
- Department of Molecular, Cellular & Biomedical Sciences, University of New Hampshire, Durham, NH 03824, United States
| | - Hieu T Nguyen
- Department of Molecular, Cellular & Biomedical Sciences, University of New Hampshire, Durham, NH 03824, United States
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126
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Engel C, Neyer S, Cramer P. Distinct Mechanisms of Transcription Initiation by RNA Polymerases I and II. Annu Rev Biophys 2018; 47:425-446. [DOI: 10.1146/annurev-biophys-070317-033058] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
RNA polymerases I and II (Pol I and Pol II) are the eukaryotic enzymes that catalyze DNA-dependent synthesis of ribosomal RNA and messenger RNA, respectively. Recent work shows that the transcribing forms of both enzymes are similar and the fundamental mechanisms of RNA chain elongation are conserved. However, the mechanisms of transcription initiation and its regulation differ between Pol I and Pol II. Recent structural studies of Pol I complexes with transcription initiation factors provided insights into how the polymerase recognizes its specific promoter DNA, how it may open DNA, and how initiation may be regulated. Comparison with the well-studied Pol II initiation system reveals a distinct architecture of the initiation complex and visualizes promoter- and gene-class-specific aspects of transcription initiation. On the basis of new structural studies, we derive a model of the Pol I transcription cycle and provide a molecular movie of Pol I transcription that can be used for teaching.
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Affiliation(s)
- Christoph Engel
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Current affiliation: Institute of Biochemistry, Genetics and Microbiology, University of Regensburg, 93053 Regensburg, Germany
| | - Simon Neyer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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127
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Babokhov M, Mosaheb MM, Baker RW, Fuchs SM. Repeat-Specific Functions for the C-Terminal Domain of RNA Polymerase II in Budding Yeast. G3 (BETHESDA, MD.) 2018; 8:1593-1601. [PMID: 29523636 PMCID: PMC5940151 DOI: 10.1534/g3.118.200086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 03/06/2018] [Indexed: 12/22/2022]
Abstract
The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAPII) is required to regulate transcription and to integrate it with other essential cellular processes. In the budding yeast Saccharomyces cerevisiae, the CTD of Rpb1p consists of 26 conserved heptad repeats that are post-translationally modified to orchestrate protein factor binding at different stages of the transcription cycle. A long-standing question in the study of the CTD is if there are any functional differences between the 26 repeats. In this study, we present evidence that repeats of identical sequence have different functions based on their position within the CTD. We assembled plasmids expressing Rpb1p with serine to alanine substitutions in three defined regions of the CTD and measured a range of phenotypes for yeast expressing these constructs. Mutations in the beginning and middle regions of the CTD had drastic, and region-specific effects, while mutating the distal region had no observable phenotype. Further mutational analysis determined that Ser5 within the first region of repeats was solely responsible for the observed growth differences and sequencing fast-growing suppressors allowed us to further define the functional regions of the CTD. This mutational analysis is consistent with current structural models for how the RNAPII holoenzyme and the CTD specifically would reside in complex with Mediator and establishes a foundation for studying regioselective binding along the repetitive RNAPII CTD.
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Affiliation(s)
| | | | - Richard W Baker
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA 92093
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128
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Weber H, Garabedian MJ. The mediator complex in genomic and non-genomic signaling in cancer. Steroids 2018; 133:8-14. [PMID: 29157917 PMCID: PMC5864542 DOI: 10.1016/j.steroids.2017.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/04/2017] [Accepted: 11/14/2017] [Indexed: 12/12/2022]
Abstract
Mediator is a conserved, multi-subunit macromolecular machine divided structurally into head, middle, and tail modules, along with a transiently associating kinase module. Mediator functions as an integrator of transcriptional regulatory activity by interacting with DNA-bound transcription factors and with RNA polymerase II (Pol II) to both activate and repress gene expression. Mediator has been shown to affect multiple steps in transcription, including chromatin looping between enhancers and promoters, pre-initiation complex formation, transcriptional elongation, and mRNA splicing. Individual Mediator subunits participate in regulation of gene expression by the estrogen and androgen receptors and are altered in a number of endocrine cancers, including breast and prostate cancer. In addition to its role in genomic signaling, MED12 has been implicated in non-genomic signaling by interacting with and activating TGF-beta receptor 2 in the cytoplasm. Recent structural studies have revealed extensive inter-domain interactions and complex architecture of the Mediator-Pol II complex, suggesting that Mediator is capable of reorganizing its conformation and composition to fit cellular needs. We propose that alterations in Mediator subunit expression that occur in various cancers could impact the organization and function of Mediator, resulting in changes in gene expression that promote malignancy. A better understanding of the role of Mediator in cancer could reveal new approaches to the diagnosis and treatment of Mediator-dependent endocrine cancers, especially in settings of therapy resistance.
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Affiliation(s)
- Hannah Weber
- Departments of Microbiology and Urology, NYU School of Medicine, 550 First Ave, New York, NY 10012, United States
| | - Michael J Garabedian
- Departments of Microbiology and Urology, NYU School of Medicine, 550 First Ave, New York, NY 10012, United States.
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129
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Rimel JK, Taatjes DJ. The essential and multifunctional TFIIH complex. Protein Sci 2018; 27:1018-1037. [PMID: 29664212 PMCID: PMC5980561 DOI: 10.1002/pro.3424] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 12/19/2022]
Abstract
TFIIH is a 10‐subunit complex that regulates RNA polymerase II (pol II) transcription but also serves other important biological roles. Although much remains unknown about TFIIH function in eukaryotic cells, much progress has been made even in just the past few years, due in part to technological advances (e.g. cryoEM and single molecule methods) and the development of chemical inhibitors of TFIIH enzymes. This review focuses on the major cellular roles for TFIIH, with an emphasis on TFIIH function as a regulator of pol II transcription. We describe the structure of TFIIH and its roles in pol II initiation, promoter‐proximal pausing, elongation, and termination. We also discuss cellular roles for TFIIH beyond transcription (e.g. DNA repair, cell cycle regulation) and summarize small molecule inhibitors of TFIIH and diseases associated with defects in TFIIH structure and function.
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Affiliation(s)
- Jenna K Rimel
- Department of Chemistry & Biochemistry, University of Colorado, Boulder, Colorado, 80303
| | - Dylan J Taatjes
- Department of Chemistry & Biochemistry, University of Colorado, Boulder, Colorado, 80303
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130
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Salinero AC, Knoll ER, Zhu ZI, Landsman D, Curcio MJ, Morse RH. The Mediator co-activator complex regulates Ty1 retromobility by controlling the balance between Ty1i and Ty1 promoters. PLoS Genet 2018; 14:e1007232. [PMID: 29462141 PMCID: PMC5834202 DOI: 10.1371/journal.pgen.1007232] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 03/02/2018] [Accepted: 01/30/2018] [Indexed: 12/24/2022] Open
Abstract
The Ty1 retrotransposons present in the genome of Saccharomyces cerevisiae belong to the large class of mobile genetic elements that replicate via an RNA intermediary and constitute a significant portion of most eukaryotic genomes. The retromobility of Ty1 is regulated by numerous host factors, including several subunits of the Mediator transcriptional co-activator complex. In spite of its known function in the nucleus, previous studies have implicated Mediator in the regulation of post-translational steps in Ty1 retromobility. To resolve this paradox, we systematically examined the effects of deleting non-essential Mediator subunits on the frequency of Ty1 retromobility and levels of retromobility intermediates. Our findings reveal that loss of distinct Mediator subunits alters Ty1 retromobility positively or negatively over a >10,000-fold range by regulating the ratio of an internal transcript, Ty1i, to the genomic Ty1 transcript. Ty1i RNA encodes a dominant negative inhibitor of Ty1 retromobility that blocks virus-like particle maturation and cDNA synthesis. These results resolve the conundrum of Mediator exerting sweeping control of Ty1 retromobility with only minor effects on the levels of Ty1 genomic RNA and the capsid protein, Gag. Since the majority of characterized intrinsic and extrinsic regulators of Ty1 retromobility do not appear to effect genomic Ty1 RNA levels, Mediator could play a central role in integrating signals that influence Ty1i expression to modulate retromobility. Retrotransposons are mobile genetic elements that copy their RNA genomes into DNA and insert the DNA copies into the host genome. These elements contribute to genome instability, control of host gene expression and adaptation to changing environments. Retrotransposons depend on numerous host factors for their own propagation and control. The retrovirus-like retrotransposon, Ty1, in the yeast Saccharomyces cerevisiae has been an invaluable model for retrotransposon research, and hundreds of host factors that regulate Ty1 retrotransposition have been identified. Non-essential subunits of the Mediator transcriptional co-activator complex have been identified as one set of host factors implicated in Ty1 regulation. Here, we report a systematic investigation of the effects of loss of these non-essential subunits of Mediator on Ty1 retrotransposition. Our findings reveal a heretofore unknown mechanism by which Mediator influences the balance between transcription from two promoters in Ty1 to modulate expression of an autoinhibitory transcript known as Ty1i RNA. Our results provide new insights into host control of retrotransposon activity via promoter choice and elucidate a novel mechanism by which the Mediator co-activator governs this choice.
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Affiliation(s)
- Alicia C. Salinero
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - Elisabeth R. Knoll
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - Z. Iris Zhu
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, Maryland, United States of America
| | - David Landsman
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, Maryland, United States of America
| | - M. Joan Curcio
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- * E-mail: (MJC); (RHM)
| | - Randall H. Morse
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- * E-mail: (MJC); (RHM)
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131
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Functions of the TFIIE-Related Tandem Winged-Helix Domain of Rpc34 in RNA Polymerase III Initiation and Elongation. Mol Cell Biol 2018; 38:MCB.00105-17. [PMID: 29180511 DOI: 10.1128/mcb.00105-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 11/22/2017] [Indexed: 12/18/2022] Open
Abstract
Rpc34 is a subunit of the Rpc82/34/31 subcomplex residing on the DNA-binding cleft of RNA polymerase (Pol) III. Rpc34 contains a structurally flexible N-terminal tandem winged-helix (tWH) domain related to the TFIIE transcription factor. While the second WH (WH2) fold of the tWH domain is known to function in DNA melting activity during transcription initiation, the functional role of the WH1 fold is unknown. In this study, we generated a series of new Rpc34 tWH mutants conferring a cold-sensitive growth phenotype. We found that the tWH mutations severely compromised in vitro transcription activity due to destabilization of the preinitiation complex (PIC). Site-specific protein photo-cross-linking analysis indicated that the tWH domain persistently interacts with protein subunits of the Pol III cleft in the PIC and the ternary elongation complex (TEC). Furthermore, purified Pol III proteins with tWH mutations also showed reduced efficiency in RNA elongation. Our study results suggest that the tWH domain is an important protein module above the Pol III cleft that integrates protein and nucleic acid interactions for initiation and elongation.
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132
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Yu C, Huang L. Cross-Linking Mass Spectrometry: An Emerging Technology for Interactomics and Structural Biology. Anal Chem 2018; 90:144-165. [PMID: 29160693 PMCID: PMC6022837 DOI: 10.1021/acs.analchem.7b04431] [Citation(s) in RCA: 222] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Clinton Yu
- Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Lan Huang
- Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697
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133
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Lv L, Liu Y, Zhang P, Bai X, Ma X, Wang Y, Li H, Wang L, Zhou Y. The epigenetic mechanisms of nanotopography-guided osteogenic differentiation of mesenchymal stem cells via high-throughput transcriptome sequencing. Int J Nanomedicine 2018; 13:5605-5623. [PMID: 30271150 PMCID: PMC6154708 DOI: 10.2147/ijn.s168928] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Nanotopography directs stem cell fate; however, the underlying mechanisms, especially those at the epigenetic level, remain vague. The TiO2-nanotube array, a classical example of nanotopography, is a good model to investigate topography-cell interactions because of its good controllability and easy manufacturing process. Previously, we found that a TiO2-nanotube array with an optimal diameter promoted osteogenic differentiation of human adipose-tissue-derived stem cells (hASCs). METHODS We used RNA sequencing and bioinformatics to reveal the overall gene expression profile of hASCs on TiO2-nanotube arrays. RESULTS Bioinformatics analyses revealed that the epigenetic regulatory network plays an important role in TiO2-nanotube-guided osteogenic differentiation. Changes in cell adhesion and cytoskeletal reorganization are linked to epigenetic alterations, including upregulation of KDM4E and downregulation of histone deacetylases. Meanwhile, microRNAs, including miR-24-1-5p, miR-24-3 p, miR-154-3 p, miR-154-5 p, miR-433-5 p, miR-589-3 p, and miR-589-5 p were downregulated, whereas miR-186-5 p and miR-770-5 p were upregulated. Long non-coding RNAs, including LINC00941, LINC01279, and ZFAS1, were downregulated in this process. CONCLUSION Using next-generation sequencing, we illustrated the overall picture of the regulatory mechanisms of TiO2 nanotubes, thus providing a basis for future clinical applications of nanotopography in the field of bone tissue engineering. Our results offer insights into material-based nanomedicine and epigenetic therapy.
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Affiliation(s)
- Longwei Lv
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Yunsong Liu
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Ping Zhang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Xiangsong Bai
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Xiaohan Ma
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Yuejun Wang
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
| | - Hongyi Li
- The key Laboratory of Advanced Functional Materials, Ministry of Education of China, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China
| | - Li Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, People's Republic of China,
| | - Yongsheng Zhou
- Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, National Clinical Research Center for Oral Disease, Beijing Key Laboratory of Digital Stomatology, Beijing, People's Republic of China,
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134
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Abstract
Cross-linking and mass spectrometry is used more and more for the structural analysis of large proteins and protein complexes. Although essentially a low-resolution method, it avoids the main drawbacks of established structural techniques. Particularly, it is largely insensitive to the inherent flexibility of the studied complexes and is applied under native conditions. It is also applicable to nearly every structural system. Therefore, cross-linking and mass spectrometry is the method of choice for elucidating the general architecture of protein complexes. Advances in instrumentation, techniques, and software now allow every lab that is working with proteins to apply the approach without much difficulty. The most specialized step in the workflow, the mass spectrometry measurement, can be done in most facilities that are performing standard proteomics. We detail here a step-by-step protocol of how to successfully apply the approach in collaboration with the mass spectrometry facility in your institution.
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135
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Yurko N, Liu X, Yamazaki T, Hoque M, Tian B, Manley JL. MPK1/SLT2 Links Multiple Stress Responses with Gene Expression in Budding Yeast by Phosphorylating Tyr1 of the RNAP II CTD. Mol Cell 2017; 68:913-925.e3. [PMID: 29220656 DOI: 10.1016/j.molcel.2017.11.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/21/2017] [Accepted: 11/15/2017] [Indexed: 12/28/2022]
Abstract
The RNA polymerase II largest subunit C-terminal domain consists of repeated YSPTSPS heptapeptides. The role of tyrosine-1 (Tyr1) remains incompletely understood, as, for example, mutating all Tyr1 residues to Phe (Y1F) is lethal in vertebrates but a related mutant has only a mild phenotype in S. pombe. Here we show that Y1F substitution in budding yeast resulted in a strong slow-growth phenotype. The Y1F strain was also hypersensitive to several different cellular stresses that involve MAP kinase signaling. These phenotypes were all linked to transcriptional changes, and we also identified genetic and biochemical interactions between Tyr1 and both transcription initiation and termination factors. Further studies uncovered defects related to MAP kinase I (Slt2) pathways, and we provide evidence that Slt2 phosphorylates Tyr1 in vitro and in vivo. Our study has thus identified Slt2 as a Tyr1 kinase, and in doing so provided links between stress response activation and Tyr1 phosphorylation.
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Affiliation(s)
- Nathan Yurko
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Xiaochuan Liu
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Takashi Yamazaki
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Mainul Hoque
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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136
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Mechanistic Differences in Transcription Initiation at TATA-Less and TATA-Containing Promoters. Mol Cell Biol 2017; 38:MCB.00448-17. [PMID: 29038161 DOI: 10.1128/mcb.00448-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/06/2017] [Indexed: 12/14/2022] Open
Abstract
A yeast in vitro system was developed that is active for transcription at both TATA-containing and TATA-less promoters. Transcription with extracts made from cells depleted of TFIID subunit Taf1 demonstrated that promoters of both classes are TFIID dependent, in agreement with recent in vivo findings. TFIID depletion can be complemented in vitro by additional recombinant TATA binding protein (TBP) at only the TATA-containing promoters. In contrast, high levels of TBP did not complement Taf1 depletion in vivo and instead repressed transcription from both promoter types. We also demonstrate the importance of the TATA-like sequence found at many TATA-less promoters and describe how the presence or absence of the TATA element is likely not the only feature that distinguishes these two types of promoters.
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137
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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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138
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Def1 interacts with TFIIH and modulates RNA polymerase II transcription. Proc Natl Acad Sci U S A 2017; 114:13230-13235. [PMID: 29180430 DOI: 10.1073/pnas.1707955114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The DNA damage response is an essential process for the survival of living cells. In a subset of stress-responsive genes in humans, Elongin controls transcription in response to multiple stimuli, such as DNA damage, oxidative stress, and heat shock. Yeast Elongin (Ela1-Elc1), along with Def1, is known to facilitate ubiquitylation and degradation of RNA polymerase II (pol II) in response to multiple stimuli, yet transcription activity has not been examined. We have found that Def1 copurifies from yeast whole-cell extract with TFIIH, the largest general transcription factor required for transcription initiation and nucleotide excision repair. The addition of recombinant Def1 and Ela1-Elc1 enhanced transcription initiation in an in vitro reconstituted system including pol II, the general transcription factors, and TFIIS. Def1 also enhanced transcription restart from TFIIS-induced cleavage in a pol II transcribing complex. In the Δdef1 strain, heat shock genes were misregulated, indicating that Def1 is required for induction of some stress-responsive genes in yeast. Taken together, our results extend the understanding of the molecular mechanism of transcription regulation on cellular stress and reveal functional similarities to the mammalian system.
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139
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Schilbach S, Hantsche M, Tegunov D, Dienemann C, Wigge C, Urlaub H, Cramer P. Structures of transcription pre-initiation complex with TFIIH and Mediator. Nature 2017; 551:204-209. [PMID: 29088706 PMCID: PMC6078178 DOI: 10.1038/nature24282] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 09/14/2017] [Indexed: 12/18/2022]
Abstract
For the initiation of transcription, RNA polymerase II (Pol II) assembles with general transcription factors on promoter DNA to form the pre-initiation complex (PIC). Here we report cryo-electron microscopy structures of the Saccharomyces cerevisiae PIC and PIC-core Mediator complex at nominal resolutions of 4.7 Å and 5.8 Å, respectively. The structures reveal transcription factor IIH (TFIIH), and suggest how the core and kinase TFIIH modules function in the opening of promoter DNA and the phosphorylation of Pol II, respectively. The TFIIH core subunit Ssl2 (a homologue of human XPB) is positioned on downstream DNA by the 'E-bridge' helix in TFIIE, consistent with TFIIE-stimulated DNA opening. The TFIIH kinase module subunit Tfb3 (MAT1 in human) anchors the kinase Kin28 (CDK7), which is mobile in the PIC but preferentially located between the Mediator hook and shoulder in the PIC-core Mediator complex. Open spaces between the Mediator head and middle modules may allow access of the kinase to its substrate, the C-terminal domain of Pol II.
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Affiliation(s)
- S Schilbach
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - M Hantsche
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - D Tegunov
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - C Dienemann
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - C Wigge
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - H Urlaub
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
- University Medical Center Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - P Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
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140
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TFIIH generates a six-base-pair open complex during RNAP II transcription initiation and start-site scanning. Nat Struct Mol Biol 2017; 24:1139-1145. [PMID: 29106413 PMCID: PMC5741190 DOI: 10.1038/nsmb.3500] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/09/2017] [Indexed: 12/23/2022]
Abstract
Eukaryotic mRNA transcription initiation is directed by the formation of the megaDalton-sized pre-initiation complex (PIC). After PIC formation, double-stranded DNA is unwound to form a single-stranded DNA bubble and the template strand is loaded into the polymerase active site. DNA opening is catalyzed by Ssl2(XPB), the dsDNA translocase subunit of the basal transcription factor TFIIH. In yeast, transcription initiation proceeds through a scanning phase where downstream DNA is searched for optimal start-sites. Here, to test models for initial DNA opening and start-site scanning, we measure the DNA bubble sizes generated by Saccharomyces cerevisiae PICs in real time using single-molecule magnetic tweezers. We show that ATP hydrolysis by Ssl2 opens a 6 base-pair (bp) bubble that grows to 13 bp in the presence of NTPs. These observations support a two-step model wherein ATP-dependent Ssl2 translocation leads to a 6 bp open complex which RNA polymerase II expands via NTP-dependent RNA transcription.
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141
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Gressel S, Schwalb B, Decker TM, Qin W, Leonhardt H, Eick D, Cramer P. CDK9-dependent RNA polymerase II pausing controls transcription initiation. eLife 2017; 6:29736. [PMID: 28994650 PMCID: PMC5669633 DOI: 10.7554/elife.29736] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/06/2017] [Indexed: 12/11/2022] Open
Abstract
Gene transcription can be activated by decreasing the duration of RNA polymerase II pausing in the promoter-proximal region, but how this is achieved remains unclear. Here we use a 'multi-omics' approach to demonstrate that the duration of polymerase pausing generally limits the productive frequency of transcription initiation in human cells ('pause-initiation limit'). We further engineer a human cell line to allow for specific and rapid inhibition of the P-TEFb kinase CDK9, which is implicated in polymerase pause release. CDK9 activity decreases the pause duration but also increases the productive initiation frequency. This shows that CDK9 stimulates release of paused polymerase and activates transcription by increasing the number of transcribing polymerases and thus the amount of mRNA synthesized per time. CDK9 activity is also associated with long-range chromatin interactions, suggesting that enhancers can influence the pause-initiation limit to regulate transcription.
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Affiliation(s)
- Saskia Gressel
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Björn Schwalb
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
| | - Tim Michael Decker
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Weihua Qin
- Department of Biology II, Ludwig-Maximilians-Universität München, Center of Integrated Protein Science, Martinsried, Germany
| | - Heinrich Leonhardt
- Department of Biology II, Ludwig-Maximilians-Universität München, Center of Integrated Protein Science, Martinsried, Germany
| | - Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
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142
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Jeronimo C, Robert F. The Mediator Complex: At the Nexus of RNA Polymerase II Transcription. Trends Cell Biol 2017; 27:765-783. [DOI: 10.1016/j.tcb.2017.07.001] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 12/15/2022]
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143
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Schmidt C, Urlaub H. Combining cryo-electron microscopy (cryo-EM) and cross-linking mass spectrometry (CX-MS) for structural elucidation of large protein assemblies. Curr Opin Struct Biol 2017; 46:157-168. [DOI: 10.1016/j.sbi.2017.10.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/21/2017] [Accepted: 10/05/2017] [Indexed: 01/11/2023]
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144
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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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145
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Med15B Regulates Acid Stress Response and Tolerance in Candida glabrata by Altering Membrane Lipid Composition. Appl Environ Microbiol 2017; 83:AEM.01128-17. [PMID: 28710262 DOI: 10.1128/aem.01128-17] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/04/2017] [Indexed: 12/16/2022] Open
Abstract
Candida glabrata is a promising producer of organic acids. To elucidate the physiological function of the Mediator tail subunit Med15B in the response to low-pH stress, we constructed a deletion strain, C. glabratamed15BΔ, and an overexpression strain, C. glabrata HTUΔ/CgMED15B Deletion of MED15B caused biomass production, glucose consumption rate, and cell viability to decrease by 28.3%, 31.7%, and 26.5%, respectively, compared with those of the parent (HTUΔ) strain at pH 2.0. Expression of lipid metabolism-related genes was significantly downregulated in the med15BΔ strain, whereas key genes of ergosterol biosynthesis showed abnormal upregulation. This caused the proportion of C18:1 fatty acids, the ratio of unsaturated to saturated fatty acids (UFA/SFA), and the total phospholipid content to decrease by 11.6%, 27.4%, and 37.6%, respectively. Cells failed to synthesize fecosterol and ergosterol, leading to the accumulation and a 60.3-fold increase in the concentration of zymosterol. Additionally, cells showed reductions of 69.2%, 11.6%, and 21.8% in membrane integrity, fluidity, and H+-ATPase activity, respectively. In contrast, overexpression of Med15B increased the C18:1 levels, total phospholipids, ergosterol content, and UFA/SFA by 18.6%, 143.5%, 94.5%, and 18.7%, respectively. Membrane integrity, fluidity, and H+-ATPase activity also increased by 30.2%, 6.9%, and 51.8%, respectively. Furthermore, in the absence of pH buffering, dry weight of cells and pyruvate concentrations were 29.3% and 61.2% higher, respectively, than those of the parent strain. These results indicated that in C. glabrata, Med15B regulates tolerance toward low pH via transcriptional regulation of acid stress response genes and alteration in lipid composition.IMPORTANCE This study explored the role of the Mediator tail subunit Med15B in the metabolism of Candida glabrata under acidic conditions. Overexpression of MED15B enhanced yeast tolerance to low pH and improved biomass production, cell viability, and pyruvate yield. Membrane lipid composition data indicated that Med15B might play a critical role in membrane integrity, fluidity, and H+-ATPase activity homeostasis at low pH. Thus, controlling membrane composition may serve to increase C. glabrata productivity at low pH.
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146
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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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147
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Cramer P. Structural Molecular Biology-A Personal Reflection on the Occasion of John Kendrew's 100th Birthday. J Mol Biol 2017; 429:2603-2610. [PMID: 28501586 DOI: 10.1016/j.jmb.2017.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 05/08/2017] [Indexed: 10/19/2022]
Abstract
Here, I discuss the development and future of structural molecular biology, concentrating on the eukaryotic transcription machinery and reflecting on John Kendrew's legacy from a personal perspective.
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Affiliation(s)
- Patrick Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany.
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148
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Abstract
To prevent tumorigenesis, p53 stimulates transcription by facilitating the recruitment of the transcription machinery on target gene promoters. Cryo-Electron Microscopy studies on p53-bound RNA Polymerase II (Pol II) reveal that p53 structurally regulates Pol II to affect its DNA binding and elongation, providing new insights into p53-mediated transcriptional regulation.
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Affiliation(s)
- Wei-Li Liu
- a Gruss-Lipper Biophotonics Center, Department of Anatomy and Structural Biology , Albert Einstein College of Medicine , Bronx , NY , USA
| | - Robert A Coleman
- a Gruss-Lipper Biophotonics Center, Department of Anatomy and Structural Biology , Albert Einstein College of Medicine , Bronx , NY , USA
| | - Sameer K Singh
- a Gruss-Lipper Biophotonics Center, Department of Anatomy and Structural Biology , Albert Einstein College of Medicine , Bronx , NY , USA
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149
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Garavís M, González-Polo N, Allepuz-Fuster P, Louro JA, Fernández-Tornero C, Calvo O. Sub1 contacts the RNA polymerase II stalk to modulate mRNA synthesis. Nucleic Acids Res 2017; 45:2458-2471. [PMID: 27924005 PMCID: PMC5389574 DOI: 10.1093/nar/gkw1206] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/18/2016] [Indexed: 12/12/2022] Open
Abstract
Biogenesis of messenger RNA is critically influenced by the phosphorylation state of the carboxy-terminal domain (CTD) in the largest RNA polymerase II (RNAPII) subunit. Several kinases and phosphatases are required to maintain proper CTD phosphorylation levels and, additionally, several other proteins modulate them, including Rpb4/7 and Sub1. The Rpb4/7 heterodimer, constituting the RNAPII stalk, promote phosphatase functions and Sub1 globally influences CTD phosphorylation, though its mechanism remains mostly unknown. Here, we show that Sub1 physically interacts with the RNAPII stalk domain, Rpb4/7, likely through its C-terminal region, and associates with Fcp1. While Rpb4 is not required for Sub1 interaction with RNAPII complex, a fully functional heterodimer is required for Sub1 association to promoters. We also demonstrate that a complete CTD is necessary for proper association of Sub1 to chromatin and to the RNAPII. Finally, genetic data show a functional relationship between Sub1 and the RNAPII clamp domain. Altogether, our results indicate that Sub1, Rpb4/7 and Fcp1 interaction modulates CTD phosphorylation. In addition, Sub1 interaction with Rpb4/7 can also modulate transcription start site selection and transcription elongation rate likely by influencing the clamp function.
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Affiliation(s)
- Miguel Garavís
- Instituto de Biología Funcional y Genómica. CSIC/Universidad de Salamanca, C/ Zacarías González 2, Salamanca 37007, Spain
| | - Noelia González-Polo
- Instituto de Biología Funcional y Genómica. CSIC/Universidad de Salamanca, C/ Zacarías González 2, Salamanca 37007, Spain
| | - Paula Allepuz-Fuster
- Instituto de Biología Funcional y Genómica. CSIC/Universidad de Salamanca, C/ Zacarías González 2, Salamanca 37007, Spain
| | - Jaime Alegrio Louro
- Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | | | - Olga Calvo
- Instituto de Biología Funcional y Genómica. CSIC/Universidad de Salamanca, C/ Zacarías González 2, Salamanca 37007, Spain
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150
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Multisubunit DNA-Dependent RNA Polymerases from Vaccinia Virus and Other Nucleocytoplasmic Large-DNA Viruses: Impressions from the Age of Structure. Microbiol Mol Biol Rev 2017; 81:81/3/e00010-17. [PMID: 28701329 DOI: 10.1128/mmbr.00010-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The past 17 years have been marked by a revolution in our understanding of cellular multisubunit DNA-dependent RNA polymerases (MSDDRPs) at the structural level. A parallel development over the past 15 years has been the emerging story of the giant viruses, which encode MSDDRPs. Here we link the two in an attempt to understand the specialization of multisubunit RNA polymerases in the domain of life encompassing the large nucleocytoplasmic DNA viruses (NCLDV), a superclade that includes the giant viruses and the biochemically well-characterized poxvirus vaccinia virus. The first half of this review surveys the recently determined structural biology of cellular RNA polymerases for a microbiology readership. The second half discusses a reannotation of MSDDRP subunits from NCLDV families and the apparent specialization of these enzymes by virus family and by subunit with regard to subunit or domain loss, subunit dissociability, endogenous control of polymerase arrest, and the elimination/customization of regulatory interactions that would confer higher-order cellular control. Some themes are apparent in linking subunit function to structure in the viral world: as with cellular RNA polymerases I and III and unlike cellular RNA polymerase II, the viral enzymes seem to opt for speed and processivity and seem to have eliminated domains associated with higher-order regulation. The adoption/loss of viral RNA polymerase proofreading functions may have played a part in matching intrinsic mutability to genome size.
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