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Barman P, Chakraborty P, Bhaumik R, Bhaumik SR. UPS writes a new saga of SAGA. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194981. [PMID: 37657588 PMCID: PMC10843445 DOI: 10.1016/j.bbagrm.2023.194981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 09/03/2023]
Abstract
SAGA (Spt-Ada-Gcn5-Acetyltransferase), an evolutionarily conserved transcriptional co-activator among eukaryotes, is a large multi-subunit protein complex with two distinct enzymatic activities, namely HAT (Histone acetyltransferase) and DUB (De-ubiquitinase), and is targeted to the promoter by the gene-specific activator proteins for histone covalent modifications and PIC (Pre-initiation complex) formation in enhancing transcription (or gene activation). Targeting of SAGA to the gene promoter is further facilitated by the 19S RP (Regulatory particle) of the 26S proteasome (that is involved in targeted degradation of protein via ubiquitylation) in a proteolysis-independent manner. Moreover, SAGA is also recently found to be regulated by the 26S proteasome in a proteolysis-dependent manner via the ubiquitylation of its Sgf73/ataxin-7 component that is required for SAGA's integrity and DUB activity (and hence transcription), and is linked to various diseases including neurodegenerative disorders and cancer. Thus, SAGA itself and its targeting to the active gene are regulated by the UPS (Ubiquitin-proteasome system) with implications in diseases.
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Affiliation(s)
- Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale IL-62901, USA
| | - Pritam Chakraborty
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale IL-62901, USA
| | - Rhea Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale IL-62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale IL-62901, USA.
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2
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Barman P, Kaja A, Chakraborty P, Guha S, Roy A, Ferdoush J, Bhaumik SR. A novel ubiquitin-proteasome system regulation of Sgf73/ataxin-7 that maintains the integrity of the coactivator SAGA in orchestrating transcription. Genetics 2023; 224:iyad071. [PMID: 37075097 PMCID: PMC10324951 DOI: 10.1093/genetics/iyad071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 01/31/2023] [Accepted: 03/15/2023] [Indexed: 04/20/2023] Open
Abstract
Ataxin-7 maintains the integrity of Spt-Ada-Gcn5-Acetyltransferase (SAGA), an evolutionarily conserved coactivator in stimulating preinitiation complex (PIC) formation for transcription initiation, and thus, its upregulation or downregulation is associated with various diseases. However, it remains unknown how ataxin-7 is regulated that could provide new insights into disease pathogenesis and therapeutic interventions. Here, we show that ataxin-7's yeast homologue, Sgf73, undergoes ubiquitylation and proteasomal degradation. Impairment of such regulation increases Sgf73's abundance, which enhances recruitment of TATA box-binding protein (TBP) (that nucleates PIC formation) to the promoter but impairs transcription elongation. Further, decreased Sgf73 level reduces PIC formation and transcription. Thus, Sgf73 is fine-tuned by ubiquitin-proteasome system (UPS) in orchestrating transcription. Likewise, ataxin-7 undergoes ubiquitylation and proteasomal degradation, alteration of which changes ataxin-7's abundance that is associated with altered transcription and cellular pathologies/diseases. Collectively, our results unveil a novel UPS regulation of Sgf73/ataxin-7 for normal cellular health and implicate alteration of such regulation in diseases.
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Affiliation(s)
- Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Amala Kaja
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX-77030, USA
| | - Pritam Chakraborty
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Arpan Roy
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Jannatul Ferdoush
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
- Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, 615 McCallie Ave, Chattanooga, TN 37403, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
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3
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Meinema AC, Marzelliusardottir A, Mirkovic M, Aspert T, Lee SS, Charvin G, Barral Y. DNA circles promote yeast ageing in part through stimulating the reorganization of nuclear pore complexes. eLife 2022; 11:71196. [PMID: 35373738 PMCID: PMC9020822 DOI: 10.7554/elife.71196] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 04/03/2022] [Indexed: 11/13/2022] Open
Abstract
The nuclear pore complex (NPC) mediates nearly all exchanges between nucleus and cytoplasm, and in many species it changes composition as the organism ages. However, how these changes arise and whether they contribute themselves to ageing is poorly understood. We show that SAGA-dependent attachment of DNA circles to NPCs in replicatively ageing yeast cells causes NPCs to lose their nuclear basket and cytoplasmic complexes. These NPCs were not recognized as defective by the NPC quality control machinery (SINC) and not targeted by ESCRTs. They interacted normally or more effectively with protein import and export factors but specifically lost mRNA export factors. Acetylation of Nup60 drove the displacement of basket and cytoplasmic complexes from circle-bound NPCs. Mutations preventing this remodeling extended the replicative lifespan of the cells. Thus, our data suggest that the anchorage of accumulating circles locks NPCs in a specialized state and that this process is intrinsically linked to the mechanisms by which ERCs promote ageing.
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Affiliation(s)
| | | | | | - Théo Aspert
- Department of Developmental Biology and Stem Cells, Institute of Genetics and Molecular and Cellular Biology, Illkirch, France
| | - Sung Sik Lee
- Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Gilles Charvin
- Department of Developmental Biology and Stem Cells, Institute of Genetics and Molecular and Cellular Biology, Illkirch, France
| | - Yves Barral
- Department of Biology, ETH Zürich, Zürich, Switzerland
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4
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Goswami R, Bello AI, Bean J, Costanzo KM, Omer B, Cornelio-Parra D, Odah R, Ahluwalia A, Allan SK, Nguyen N, Shores T, Aziz NA, Mohan RD. The Molecular Basis of Spinocerebellar Ataxia Type 7. Front Neurosci 2022; 16:818757. [PMID: 35401096 PMCID: PMC8987156 DOI: 10.3389/fnins.2022.818757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/07/2022] [Indexed: 11/19/2022] Open
Abstract
Spinocerebellar ataxia (SCA) type 7 (SCA7) is caused by a CAG trinucleotide repeat expansion in the ataxin 7 (ATXN7) gene, which results in polyglutamine expansion at the amino terminus of the ATXN7 protein. Although ATXN7 is expressed widely, the best characterized symptoms of SCA7 are remarkably tissue specific, including blindness and degeneration of the brain and spinal cord. While it is well established that ATXN7 functions as a subunit of the Spt Ada Gcn5 acetyltransferase (SAGA) chromatin modifying complex, the mechanisms underlying SCA7 remain elusive. Here, we review the symptoms of SCA7 and examine functions of ATXN7 that may provide further insights into its pathogenesis. We also examine phenotypes associated with polyglutamine expanded ATXN7 that are not considered symptoms of SCA7.
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Affiliation(s)
- Rituparna Goswami
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Abudu I. Bello
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Joe Bean
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Kara M. Costanzo
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Bwaar Omer
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Dayanne Cornelio-Parra
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Revan Odah
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Amit Ahluwalia
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Shefaa K. Allan
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Nghi Nguyen
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - Taylor Shores
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
| | - N. Ahmad Aziz
- Population Health Sciences, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ryan D. Mohan
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO, United States
- *Correspondence: Ryan D. Mohan,
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5
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Soffers JHM, Workman JL. The SAGA chromatin-modifying complex: the sum of its parts is greater than the whole. Genes Dev 2021; 34:1287-1303. [PMID: 33004486 PMCID: PMC7528701 DOI: 10.1101/gad.341156.120] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this review, Soffers and Workman discuss the initial discovery of the canonical SAGA complex, the subsequent studies that have shaped our view on the internal organization of its subunits into modules, and the latest structural work that visualizes the modules and provides insights into their function. There are many large protein complexes involved in transcription in a chromatin context. However, recent studies on the SAGA coactivator complex are generating new paradigms for how the components of these complexes function, both independently and in concert. This review highlights the initial discovery of the canonical SAGA complex 23 years ago, our evolving understanding of its modular structure and the relevance of its modular nature for its coactivator function in gene regulation.
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Affiliation(s)
- Jelly H M Soffers
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | - Jerry L Workman
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
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6
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Nuño-Cabanes C, García-Molinero V, Martín-Expósito M, Gas ME, Oliete-Calvo P, García-Oliver E, de la Iglesia-Vayá M, Rodríguez-Navarro S. SAGA-CORE subunit Spt7 is required for correct Ubp8 localization, chromatin association and deubiquitinase activity. Epigenetics Chromatin 2020; 13:46. [PMID: 33115507 PMCID: PMC7594455 DOI: 10.1186/s13072-020-00367-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/15/2020] [Indexed: 02/07/2023] Open
Abstract
Background Histone H2B deubiquitination is performed by numerous deubiquitinases in eukaryotic cells including Ubp8, the catalytic subunit of the tetrameric deubiquitination module (DUBm: Ubp8; Sus1; Sgf11; Sgf73) of the Spt-Ada-Gcn5 acetyltransferase (SAGA). Ubp8 is linked to the rest of SAGA through Sgf73 and is activated by the adaptors Sus1 and Sgf11. It is unknown if DUBm/Ubp8 might also work in a SAGA-independent manner. Results Here we report that a tetrameric DUBm is assembled independently of the SAGA–CORE components SPT7, ADA1 and SPT20. In the absence of SPT7, i.e., independent of the SAGA complex, Ubp8 and Sus1 are poorly recruited to SAGA-dependent genes and to chromatin. Notably, cells lacking Spt7 or Ada1, but not Spt20, show lower levels of nuclear Ubp8 than wild-type cells, suggesting a possible role for SAGA–CORE subunits in Ubp8 localization. Last, deletion of SPT7 leads to defects in Ubp8 deubiquitinase activity in in vivo and in vitro assays. Conclusions Collectively, our studies show that the DUBm tetrameric structure can form without a complete intact SAGA–CORE complex and that it includes full-length Sgf73. However, subunits of this SAGA–CORE influence DUBm association with chromatin, its localization and its activity.
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Affiliation(s)
- Carme Nuño-Cabanes
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), C/Jaume Roig 11, 46010, Valencia, Spain.,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - Varinia García-Molinero
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - Manuel Martín-Expósito
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), C/Jaume Roig 11, 46010, Valencia, Spain.,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - María-Eugenia Gas
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - Paula Oliete-Calvo
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - Encar García-Oliver
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - María de la Iglesia-Vayá
- Brain Connectivity Lab. Joint Unit FISABIO & Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain
| | - Susana Rodríguez-Navarro
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), C/Jaume Roig 11, 46010, Valencia, Spain. .,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), C/E. Primo Yúfera 3, 46012, Valencia, Spain.
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7
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Ben-Shem A, Papai G, Schultz P. Architecture of the multi-functional SAGA complex and the molecular mechanism of holding TBP. FEBS J 2020; 288:3135-3147. [PMID: 32946670 DOI: 10.1111/febs.15563] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/11/2020] [Accepted: 09/10/2020] [Indexed: 12/25/2022]
Abstract
In eukaryotes, transcription of protein encoding genes is initiated by the controlled deposition of the TATA-box binding protein TBP onto gene promoters, followed by the ordered assembly of a pre-initiation complex. The SAGA co-activator is a 19-subunit complex that stimulates transcription by the action of two chromatin-modifying enzymatic modules, a transcription activator binding module, and by delivering TBP. Recent cryo electron microscopy structures of yeast SAGA with bound nucleosome or TBP reveal the architecture of the different functional domains of the co-activator. An octamer of histone fold domains is found at the core of SAGA. This octamer, which deviates considerably from the symmetrical analogue forming the nucleosome, establishes a peripheral site for TBP binding where steric hindrance represses interaction with spurious DNA. The structures point to a mechanism for TBP delivery and release from SAGA that requires TFIIA and whose efficiency correlates with the affinity of DNA to TBP. These results provide a structural basis for understanding specific TBP delivery onto gene promoters and the role played by SAGA in regulating gene expression. The properties of the TBP delivery machine harboured by SAGA are compared with the TBP loading device present in the TFIID complex and show multiple similitudes.
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Affiliation(s)
- Adam Ben-Shem
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Institut National de la Santé et de la Recherche Médicale, U1258, Université de Strasbourg, France.,Equipe labellisée Ligue Contre le Cancer, France
| | - Gabor Papai
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Institut National de la Santé et de la Recherche Médicale, U1258, Université de Strasbourg, France.,Equipe labellisée Ligue Contre le Cancer, France
| | - Patrick Schultz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Institut National de la Santé et de la Recherche Médicale, U1258, Université de Strasbourg, France.,Equipe labellisée Ligue Contre le Cancer, France
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8
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Cheon Y, Kim H, Park K, Kim M, Lee D. Dynamic modules of the coactivator SAGA in eukaryotic transcription. Exp Mol Med 2020; 52:991-1003. [PMID: 32616828 PMCID: PMC8080568 DOI: 10.1038/s12276-020-0463-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 02/08/2023] Open
Abstract
SAGA (Spt-Ada-Gcn5 acetyltransferase) is a highly conserved transcriptional coactivator that consists of four functionally independent modules. Its two distinct enzymatic activities, histone acetylation and deubiquitylation, establish specific epigenetic patterns on chromatin and thereby regulate gene expression. Whereas earlier studies emphasized the importance of SAGA in regulating global transcription, more recent reports have indicated that SAGA is involved in other aspects of gene expression and thus plays a more comprehensive role in regulating the overall process. Here, we discuss recent structural and functional studies of each SAGA module and compare the subunit compositions of SAGA with related complexes in yeast and metazoans. We discuss the regulatory role of the SAGA deubiquitylating module (DUBm) in mRNA surveillance and export, and in transcription initiation and elongation. The findings suggest that SAGA plays numerous roles in multiple stages of transcription. Further, we describe how SAGA is related to human disease. Overall, in this report, we illustrate the newly revealed understanding of SAGA in transcription regulation and disease implications for fine-tuning gene expression. A protein that helps add epigenetic information to genome, SAGA, controls many aspects of gene activation, potentially making it a target for cancer therapies. To fit inside the tiny cell nucleus, the genome is tightly packaged, and genes must be unpacked before they can be activated. Known to be important in genome opening, SAGA has now been shown to also play many roles in gene activation. Daeyoup Lee at the KAIST, Daejeon, South Korea, and co-workers have reviewed recent discoveries about SAGA’s structure, function, and roles in disease. They report that SAGA’s complex (19 subunits organized into four modules) allows it to play so many roles, genome opening, initiating transcription, and efficiently exporting mRNAs. Its master role means that malfunction of SAGA may be linked to many diseases.
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Affiliation(s)
- Youngseo Cheon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
| | - Harim Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
| | - Kyubin Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
| | - Minhoo Kim
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, 90089, USA
| | - Daeyoup Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea.
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9
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Mustachio LM, Roszik J, Farria A, Dent SYR. Targeting the SAGA and ATAC Transcriptional Coactivator Complexes in MYC-Driven Cancers. Cancer Res 2020; 80:1905-1911. [PMID: 32094302 DOI: 10.1158/0008-5472.can-19-3652] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/28/2020] [Accepted: 02/19/2020] [Indexed: 12/26/2022]
Abstract
Targeting epigenetic regulators, such as histone-modifying enzymes, provides novel strategies for cancer therapy. The GCN5 lysine acetyltransferase (KAT) functions together with MYC both during normal development and in oncogenesis. As transcription factors, MYC family members are difficult to target with small-molecule inhibitors, but the acetyltransferase domain and the bromodomain in GCN5 might provide alternative targets for disruption of MYC-driven functions. GCN5 is part of two distinct multiprotein histone-modifying complexes, SAGA and ATAC. This review summarizes key findings on the roles of SAGA and ATAC in embryo development and in cancer to better understand the functional relationships of these complexes with MYC family members, as well as their future potential as therapeutic targets.
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Affiliation(s)
- Lisa Maria Mustachio
- Departments of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas.,Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jason Roszik
- Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.,Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Aimee Farria
- Departments of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas.,Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, Texas.,Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Sharon Y R Dent
- Departments of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas. .,Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, Texas.,Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, Texas
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10
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Cheung ACM, Díaz-Santín LM. Share and share alike: the role of Tra1 from the SAGA and NuA4 coactivator complexes. Transcription 2019; 10:37-43. [PMID: 30375921 PMCID: PMC6351133 DOI: 10.1080/21541264.2018.1530936] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/21/2018] [Accepted: 09/24/2018] [Indexed: 01/12/2023] Open
Abstract
SAGA and NuA4 are coactivator complexes required for transcription on chromatin. Although they contain different enzymatic and biochemical activities, both contain the large Tra1 subunit. Recent electron microscopy studies have resolved the complete structure of Tra1 and its integration in SAGA/NuA4, providing important insight into Tra1 function.
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Affiliation(s)
- Alan C. M. Cheung
- Department of Structural and Molecular Biology, University College London, Institute of Structural and Molecular Biology, London, UK
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, UK
| | - Luis Miguel Díaz-Santín
- Department of Structural and Molecular Biology, University College London, Institute of Structural and Molecular Biology, London, UK
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, UK
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11
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Nassrallah A, Rougée M, Bourbousse C, Drevensek S, Fonseca S, Iniesto E, Ait-Mohamed O, Deton-Cabanillas AF, Zabulon G, Ahmed I, Stroebel D, Masson V, Lombard B, Eeckhout D, Gevaert K, Loew D, Genovesio A, Breyton C, De Jaeger G, Bowler C, Rubio V, Barneche F. DET1-mediated degradation of a SAGA-like deubiquitination module controls H2Bub homeostasis. eLife 2018; 7:37892. [PMID: 30192741 PMCID: PMC6128693 DOI: 10.7554/elife.37892] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 08/22/2018] [Indexed: 12/11/2022] Open
Abstract
DE-ETIOLATED 1 (DET1) is an evolutionarily conserved component of the ubiquitination machinery that mediates the destabilization of key regulators of cell differentiation and proliferation in multicellular organisms. In this study, we provide evidence from Arabidopsis that DET1 is essential for the regulation of histone H2B monoubiquitination (H2Bub) over most genes by controlling the stability of a deubiquitination module (DUBm). In contrast with yeast and metazoan DUB modules that are associated with the large SAGA complex, the Arabidopsis DUBm only comprises three proteins (hereafter named SGF11, ENY2 and UBP22) and appears to act independently as a major H2Bub deubiquitinase activity. Our study further unveils that DET1-DDB1-Associated-1 (DDA1) protein interacts with SGF11 in vivo, linking the DET1 complex to light-dependent ubiquitin-mediated proteolytic degradation of the DUBm. Collectively, these findings uncover a signaling path controlling DUBm availability, potentially adjusting H2Bub turnover capacity to the cell transcriptional status.
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Affiliation(s)
- Amr Nassrallah
- Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Martin Rougée
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France.,Université Paris-Sud, Orsay, France
| | - Clara Bourbousse
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France.,Université Paris-Sud, Orsay, France
| | - Stephanie Drevensek
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Sandra Fonseca
- Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Elisa Iniesto
- Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Ouardia Ait-Mohamed
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Anne-Flore Deton-Cabanillas
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Gerald Zabulon
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Ikhlak Ahmed
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - David Stroebel
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Vanessa Masson
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie PSL Research University, 75005 Paris, France
| | - Berangere Lombard
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie PSL Research University, 75005 Paris, France
| | - Dominique Eeckhout
- Department of Plant Systems Biology, Ghent University, Ghent, Belgium.,VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Kris Gevaert
- Department of Biochemistry, Ghent University, Ghent, Belgium.,VIB Center for Medical Biotechnology, Ghent, Belgium
| | - Damarys Loew
- Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie PSL Research University, 75005 Paris, France
| | - Auguste Genovesio
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Cecile Breyton
- Université Grenoble Alpes, Institut de Biologie Structurale, Grenoble, France
| | - Geert De Jaeger
- Department of Plant Systems Biology, Ghent University, Ghent, Belgium.,VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Chris Bowler
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
| | - Vicente Rubio
- Centro Nacional de Biotecnología, CNB-CSIC, Madrid, Spain
| | - Fredy Barneche
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, Université PSL, Paris, France
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12
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Mittal C, Culbertson SJ, Shogren-Knaak MA. Distinct requirements of linker DNA and transcriptional activators in promoting SAGA-mediated nucleosome acetylation. J Biol Chem 2018; 293:13736-13749. [PMID: 30054274 DOI: 10.1074/jbc.ra118.004487] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 07/20/2018] [Indexed: 01/08/2023] Open
Abstract
The Spt-Ada-Gcn5 acetyltransferase (SAGA) family of transcriptional coactivators are prototypical nucleosome acetyltransferase complexes that regulate multiple steps in gene transcription. The size and complexity of both the SAGA enzyme and the chromatin substrate provide numerous opportunities for regulating the acetylation process. To better probe this regulation, here we developed a bead-based nucleosome acetylation assay to characterize the binding interactions and kinetics of acetylation with different nucleosomal substrates and the full SAGA complex purified from budding yeast (Saccharomyces cerevisiae). We found that SAGA-mediated nucleosome acetylation is stimulated up to 9-fold by DNA flanking the nucleosome, both by facilitating the binding of SAGA and by accelerating acetylation turnover. This stimulation required that flanking DNA is present on both sides of the nucleosome and that one side is >15 bp long. The Gal4-VP16 transcriptional activator fusion protein could also augment nucleosome acetylation up to 5-fold. However, contrary to our expectations, this stimulation did not appear to occur by stabilizing the binding of SAGA toward nucleosomes containing an activator-binding site. Instead, increased acetylation turnover by SAGA stimulated nucleosome acetylation. These results suggest that the Gal4-VP16 transcriptional activator directly stimulates acetylation via a dual interaction with both flanking DNA and SAGA. Altogether, these findings uncover several critical mechanisms of SAGA regulation by chromatin substrates.
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Affiliation(s)
- Chitvan Mittal
- From the Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - Sannie J Culbertson
- From the Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - Michael A Shogren-Knaak
- From the Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011
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13
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Pfab A, Bruckmann A, Nazet J, Merkl R, Grasser KD. The Adaptor Protein ENY2 Is a Component of the Deubiquitination Module of the Arabidopsis SAGA Transcriptional Co-activator Complex but not of the TREX-2 Complex. J Mol Biol 2018; 430:1479-1494. [PMID: 29588169 DOI: 10.1016/j.jmb.2018.03.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/20/2018] [Accepted: 03/20/2018] [Indexed: 12/26/2022]
Abstract
The conserved nuclear protein ENY2 (Sus1 in yeast) is involved in coupling transcription and mRNA export in yeast and metazoa, as it is a component both of the transcriptional co-activator complex SAGA and of the mRNA export complex TREX-2. Arabidopsis thaliana ENY2 is widely expressed in the plant and it localizes to the nucleoplasm, but unlike its yeast/metazoan orthologs, it is not enriched in the nuclear envelope. Affinity purification of ENY2 in combination with mass spectrometry revealed that it co-purified with SAGA components, but not with the nuclear pore-associated TREX-2. In addition, further targeted proteomics analyses by reciprocal tagging established the composition of the Arabidopsis SAGA complex consisting of the four modules HATm, SPTm, TAFm and DUBm, and that several SAGA subunits occur in alternative variants. While the HATm, SPTm and TAFm robustly co-purified with each other, the deubiquitination module (DUBm) appears to associate with the other SAGA modules more weakly/dynamically. Consistent with a homology model of the Arabidopsis DUBm, the SGF11 protein interacts directly with ENY2 and UBP22. Plants depleted in the DUBm components, SGF11 or ENY2, are phenotypically only mildly affected, but they contain increased levels of ubiquitinated histone H2B, indicating that the SAGA-DUBm has histone deubiquitination activity in plants. In addition to transcription-related proteins (i.e., transcript elongation factors, Mediator), many splicing factors were found to associate with SAGA, linking the SAGA complex and ongoing transcription with mRNA processing.
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Affiliation(s)
- Alexander Pfab
- Department of Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Astrid Bruckmann
- Department for Biochemistry I, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Julian Nazet
- Department for Biochemistry II, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Rainer Merkl
- Department for Biochemistry II, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Klaus D Grasser
- Department of Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany.
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14
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Architecture of the Saccharomyces cerevisiae NuA4/TIP60 complex. Nat Commun 2018; 9:1147. [PMID: 29559617 PMCID: PMC5861120 DOI: 10.1038/s41467-018-03504-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 02/19/2018] [Indexed: 01/06/2023] Open
Abstract
The NuA4/TIP60 acetyltransferase complex is required for gene regulation, DNA repair and cell cycle progression. The limited structural information impeded understanding of NuA4/TIP60 assembly and regulatory mechanism. Here, we report the 4.7 Å cryo-electron microscopy (cryo-EM) structure of a NuA4/TIP60 TEEAA assembly (Tra1, Eaf1, Eaf5, actin and Arp4) and the 7.6 Å cryo-EM structure of a TEEAA-piccolo assembly (Esa1, Epl1, Yng2 and Eaf6). The Tra1 and Eaf1 constitute the assembly scaffold. The Eaf1 SANT domain tightly binds to the LBE and FATC domains of Tra1 by ionic interactions. The actin/Arp4 peripherally associates with Eaf1 HSA domain. The Eaf5/7/3 (TINTIN) and piccolo modules largely pack against the FAT and HEAT repeats of Tra1 and their association depends on Eaf1 N-terminal and HSA regions, respectively. These structures elucidate the detailed architecture and molecular interactions between NuA4 subunits and offer exciting insights into the scaffolding and regulatory mechanisms of Tra1 pseudokinase. The NuA4 histone acetyltransferase complex is important for gene regulation, DNA repair processes and cell cycle progression. Here the authors give molecular insights into the NuA4 complex by presenting the cryo-EM structures of the NuA4 TEEAA (Tra1, Eaf1, Eaf5, actin, and Arp4) and TEEAA-piccolo NuA4 assemblies.
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15
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Watanabe K, Kokubo T. SAGA mediates transcription from the TATA-like element independently of Taf1p/TFIID but dependent on core promoter structures in Saccharomyces cerevisiae. PLoS One 2017; 12:e0188435. [PMID: 29176831 PMCID: PMC5703507 DOI: 10.1371/journal.pone.0188435] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/07/2017] [Indexed: 11/21/2022] Open
Abstract
In Saccharomyces cerevisiae, core promoters of class II genes contain a TATA element, either a TATA box (TATA[A/T]A[A/T][A/G]) or TATA-like element (1 or 2 bp mismatched version of the TATA box). The TATA element directs the assembly of the preinitiation complex (PIC) to ensure accurate transcriptional initiation. It has been proposed the PIC is assembled by two distinct pathways in which TBP is delivered by TFIID or SAGA, leading to the widely accepted model that these complexes mediate transcription mainly from TATA-like element- or TATA box-containing promoters, respectively. Although both complexes are involved in transcription of nearly all class II genes, it remains unclear how efficiently SAGA mediates transcription from TATA-like element-containing promoters independently of TFIID. We found that transcription from the TATA box-containing AGP1 promoter was greatly stimulated in a Spt3p-dependent manner after inactivation of Taf1p/TFIID. Thus, this promoter provides a novel experimental system in which to evaluate SAGA-mediated transcription from TATA-like element(s). We quantitatively measured transcription from various TATA-like elements in the Taf1p-dependent CYC1 promoter and Taf1p-independent AGP1 promoter. The results revealed that SAGA could mediate transcription from at least some TATA-like elements independently of Taf1p/TFIID, and that Taf1p-dependence or -independence is highly robust with respect to variation of the TATA sequence. Furthermore, chimeric promoter mapping revealed that Taf1p-dependence or independence was conferred by the upstream activating sequence (UAS), whereas Spt3p-dependent transcriptional stimulation after inactivation of Taf1p/TFIID was specific to the AGP1 promoter and dependent on core promoter regions other than the TATA box. These results suggest that TFIID and/or SAGA are regulated in two steps: the UAS first specifies TFIID or SAGA as the predominant factor on a given promoter, and then the core promoter structure guides the pertinent factor to conduct transcription in an appropriate manner.
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Affiliation(s)
- Kiyoshi Watanabe
- Molecular and Cellular Biology Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Tetsuro Kokubo
- Molecular and Cellular Biology Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa, Japan
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16
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Structure of the transcription activator target Tra1 within the chromatin modifying complex SAGA. Nat Commun 2017; 8:1556. [PMID: 29146944 PMCID: PMC5691046 DOI: 10.1038/s41467-017-01564-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 09/27/2017] [Indexed: 12/21/2022] Open
Abstract
The transcription co-activator complex SAGA is recruited to gene promoters by sequence-specific transcriptional activators and by chromatin modifications to promote pre-initiation complex formation. The yeast Tra1 subunit is the major target of acidic activators such as Gal4, VP16, or Gcn4 but little is known about its structural organization. The 430 kDa Tra1 subunit and its human homolog the transformation/transcription domain-associated protein TRRAP are members of the phosphatidyl 3-kinase-related kinase (PIKK) family. Here, we present the cryo-EM structure of the entire SAGA complex where the major target of activator binding, the 430 kDa Tra1 protein, is resolved with an average resolution of 5.7 Å. The high content of alpha-helices in Tra1 enabled tracing of the majority of its main chain. Our results highlight the integration of Tra1 within the major epigenetic regulator SAGA. The transcription co-activator complex SAGA is recruited to promoters by transcriptional activators and promotes the formation of the pre-initiation complex. Here, the authors present the cryo-EM structure of the SAGA complex and resolve the major target of activator binding, the 430 kDa Tra1 protein.
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17
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Helmlinger D, Tora L. Sharing the SAGA. Trends Biochem Sci 2017; 42:850-861. [PMID: 28964624 PMCID: PMC5660625 DOI: 10.1016/j.tibs.2017.09.001] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/30/2017] [Accepted: 09/05/2017] [Indexed: 12/14/2022]
Abstract
Transcription initiation is a major regulatory step in eukaryotic gene expression. Co-activators establish transcriptionally competent promoter architectures and chromatin signatures to allow the formation of the pre-initiation complex (PIC), comprising RNA polymerase II (Pol II) and general transcription factors (GTFs). Many GTFs and co-activators are multisubunit complexes, in which individual components are organized into functional modules carrying specific activities. Recent advances in affinity purification and mass spectrometry analyses have revealed that these complexes often share functional modules, rather than containing unique components. This observation appears remarkably prevalent for chromatin-modifying and remodeling complexes. Here, we use the modular organization of the evolutionary conserved Spt-Ada-Gcn5 acetyltransferase (SAGA) complex as a paradigm to illustrate how co-activators share and combine a relatively limited set of functional tools.
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Affiliation(s)
| | - László Tora
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France; Université de Strasbourg, 67404 Illkirch, France.
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18
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Laboucarié T, Detilleux D, Rodriguez-Mias RA, Faux C, Romeo Y, Franz-Wachtel M, Krug K, Maček B, Villén J, Petersen J, Helmlinger D. TORC1 and TORC2 converge to regulate the SAGA co-activator in response to nutrient availability. EMBO Rep 2017; 18:2197-2218. [PMID: 29079657 DOI: 10.15252/embr.201744942] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/31/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022] Open
Abstract
Gene expression regulation is essential for cells to adapt to changes in their environment. Co-activator complexes have well-established roles in transcriptional regulation, but less is known about how they sense and respond to signaling cues. We have previously shown that, in fission yeast, one such co-activator, the SAGA complex, controls gene expression and the switch from proliferation to differentiation in response to nutrient availability. Here, using a combination of genetic, biochemical, and proteomic approaches, we show that SAGA responds to nutrients through the differential phosphorylation of its Taf12 component, downstream of both the TORC1 and TORC2 pathways. Taf12 phosphorylation increases early upon starvation and is controlled by the opposing activities of the PP2A phosphatase, which is activated by TORC1, and the TORC2-activated Gad8AKT kinase. Mutational analyses suggest that Taf12 phosphorylation prevents cells from committing to differentiation until starvation reaches a critical level. Overall, our work reveals that SAGA is a direct target of nutrient-sensing pathways and has uncovered a mechanism by which TORC1 and TORC2 converge to control gene expression and cell fate decisions.
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Affiliation(s)
| | | | | | - Céline Faux
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | - Yves Romeo
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | | | | | - Boris Maček
- Proteome Center Tübingen, Tuebingen, Germany
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Janni Petersen
- Flinders Centre for Innovation in Cancer, School of Medicine, Faculty of Health Science, Flinders University, Adelaide, SA, Australia
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19
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Kassem S, Villanyi Z, Collart MA. Not5-dependent co-translational assembly of Ada2 and Spt20 is essential for functional integrity of SAGA. Nucleic Acids Res 2017; 45:1186-1199. [PMID: 28180299 PMCID: PMC5388395 DOI: 10.1093/nar/gkw1059] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 10/04/2016] [Accepted: 10/22/2016] [Indexed: 11/13/2022] Open
Abstract
Acetylation of histones regulates gene expression in eukaryotes. In the yeast Saccharomyces cerevisiae it depends mainly upon the ADA and SAGA histone acetyltransferase complexes for which Gcn5 is the catalytic subunit. Previous screens have determined that global acetylation is reduced in cells lacking subunits of the Ccr4–Not complex, a global regulator of eukaryotic gene expression. In this study we have characterized the functional connection between the Ccr4–Not complex and SAGA. We show that SAGA mRNAs encoding a core set of SAGA subunits are tethered together for co-translational assembly of the encoded proteins. Ccr4–Not subunits bind SAGA mRNAs and promote the co-translational assembly of these subunits. This is needed for integrity of SAGA. In addition, we determine that a glycolytic enzyme, the glyceraldehyde-3-phosphate dehydrogenase Tdh3, a prototypical moonlighting protein, is tethered at this site of Ccr4–Not-dependent co-translational SAGA assembly and functions as a chaperone.
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Affiliation(s)
- Sari Kassem
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, Institute of Genetics and Genomics Geneva, University of Geneva, Geneva, Switzerland
| | - Zoltan Villanyi
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, Institute of Genetics and Genomics Geneva, University of Geneva, Geneva, Switzerland
| | - Martine A Collart
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, Institute of Genetics and Genomics Geneva, University of Geneva, Geneva, Switzerland
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20
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Díaz-Santín LM, Lukoyanova N, Aciyan E, Cheung AC. Cryo-EM structure of the SAGA and NuA4 coactivator subunit Tra1 at 3.7 angstrom resolution. eLife 2017; 6:28384. [PMID: 28767037 PMCID: PMC5576489 DOI: 10.7554/elife.28384] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/31/2017] [Indexed: 01/30/2023] Open
Abstract
Coactivator complexes SAGA and NuA4 stimulate transcription by post-translationally modifying chromatin. Both complexes contain the Tra1 subunit, a highly conserved 3744-residue protein from the Phosphoinositide 3-Kinase-related kinase (PIKK) family and a direct target for multiple sequence-specific activators. We present the Cryo-EM structure of Saccharomyces cerevsisae Tra1 to 3.7 Å resolution, revealing an extensive network of alpha-helical solenoids organized into a diamond ring conformation and is strikingly reminiscent of DNA-PKcs, suggesting a direct role for Tra1 in DNA repair. The structure was fitted into an existing SAGA EM reconstruction and reveals limited contact surfaces to Tra1, hence it does not act as a molecular scaffold within SAGA. Mutations that affect activator targeting are distributed across the Tra1 structure, but also cluster within the N-terminal Finger region, indicating the presence of an activator interaction site. The structure of Tra1 is a key milestone in deciphering the mechanism of multiple coactivator complexes. Inside our cells, histone proteins package and condense DNA so that it can fit into the cell nucleus. However, this also switches off the genes, since the machines that read and interpret them can no longer access the underlying DNA. Turning genes on requires specific enzymes that chemically modify the histone proteins to regain access to the DNA. This must be carefully controlled, otherwise the ‘wrong’ genes can be activated, causing undesired effects and endangering the cell. Histone modifying enzymes often reside in large protein complexes. Two well-known examples are the SAGA and NuA4 complexes. Both have different roles during gene activation, but share a protein called Tra1. This protein enables SAGA and NuA4 to act on specific genes by binding to ‘activator proteins’ that are found on the DNA. Tra1 is one of the biggest proteins in the cell, but its size makes it difficult to study and until now, its structure was unknown. To determine the structure of Tra1, Díaz-Santín et al. extracted the protein from baker’s yeast, and examined it using electron microscopy. The structure of Tra1 resembled a diamond ring with multiple protein domains that correspond to a band, setting and a centre stone. The structure was detailed enough so that Díaz-Santín et al. could locate various mutations that affect the role of Tra1. These locations are likely to be direct interfaces to the ‘activator proteins’. Moreover, the study showed that Tra1 was similar to another protein that repairs damaged DNA. These results suggest that Tra1 not only works as an activator target, but may also have a role in repairing damaged DNA, and might even connect these two processes. Yeast Tra1 is also very similar to its human counterpart, which has been shown to stimulate cells to become cancerous. Further studies based on these results may help us understand how cancer begins.
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Affiliation(s)
- Luis Miguel Díaz-Santín
- Department of Structural and Molecular Biology, Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Natasha Lukoyanova
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
| | - Emir Aciyan
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
| | - Alan Cm Cheung
- Department of Structural and Molecular Biology, Institute of Structural and Molecular Biology, University College London, London, United Kingdom.,Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
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21
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Dewhurst-Maridor G, Abegg D, David FPA, Rougemont J, Scott CC, Adibekian A, Riezman H. The SAGA complex, together with transcription factors and the endocytic protein Rvs167p, coordinates the reprofiling of gene expression in response to changes in sterol composition in Saccharomyces cerevisiae. Mol Biol Cell 2017; 28:2637-2649. [PMID: 28768829 PMCID: PMC5620372 DOI: 10.1091/mbc.e17-03-0169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 07/21/2017] [Accepted: 07/28/2017] [Indexed: 01/26/2023] Open
Abstract
The SAGA complex, together with transcription factors and Rvs167p, coordinates sterol-dependent transcription changes. In ergosterol mutants the SAGA complex increases its occupancy on ergosterol biosynthesis and anaerobic gene promoters, recruits the SWI/SNF complex, and binds to transcription factors and Rvs167p. Genes encoding stress proteins and basic amino acid synthesis are also affected even though promoter occupancy is not changed. Changes in cellular sterol species and concentrations can have profound effects on the transcriptional profile. In yeast, mutants defective in sterol biosynthesis show a wide range of changes in transcription, including a coinduction of anaerobic genes and ergosterol biosynthesis genes, biosynthesis of basic amino acids, and several stress genes. However the mechanisms underlying these changes are unknown. We identified mutations in the SAGA complex, a coactivator of transcription, which abrogate the ability to carry out most of these sterol-dependent transcriptional changes. In the erg3 mutant, the SAGA complex increases its occupancy time on many of the induced ergosterol and anaerobic gene promoters, increases its association with several relevant transcription factors and the SWI/SNF chromatin remodeling complex, and surprisingly, associates with an endocytic protein, Rvs167p, suggesting a moonlighting function for this protein in the sterol-regulated induction of the heat shock protein, HSP42 and HSP102, mRNAs.
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Affiliation(s)
| | - Daniel Abegg
- Department of Organic Chemistry, University of Geneva, 1205 Geneva, Switzerland.,NCCR Chemical Biology, University of Geneva, 1205 Geneva, Switzerland
| | - Fabrice P A David
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Jacques Rougemont
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Cameron C Scott
- Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland.,Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland
| | - Alexander Adibekian
- Department of Organic Chemistry, University of Geneva, 1205 Geneva, Switzerland.,NCCR Chemical Biology, University of Geneva, 1205 Geneva, Switzerland
| | - Howard Riezman
- Department of Biochemistry, University of Geneva, 1205 Geneva, Switzerland .,NCCR Chemical Biology, University of Geneva, 1205 Geneva, Switzerland
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22
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Vlaming H, Molenaar TM, van Welsem T, Poramba-Liyanage DW, Smith DE, Velds A, Hoekman L, Korthout T, Hendriks S, Altelaar AFM, van Leeuwen F. Direct screening for chromatin status on DNA barcodes in yeast delineates the regulome of H3K79 methylation by Dot1. eLife 2016; 5. [PMID: 27922451 PMCID: PMC5179194 DOI: 10.7554/elife.18919] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 12/02/2016] [Indexed: 12/22/2022] Open
Abstract
Given the frequent misregulation of chromatin in cancer, it is important to understand the cellular mechanisms that regulate chromatin structure. However, systematic screening for epigenetic regulators is challenging and often relies on laborious assays or indirect reporter read-outs. Here we describe a strategy, Epi-ID, to directly assess chromatin status in thousands of mutants. In Epi-ID, chromatin status on DNA barcodes is interrogated by chromatin immunoprecipitation followed by deep sequencing, allowing for quantitative comparison of many mutants in parallel. Screening of a barcoded yeast knock-out collection for regulators of histone H3K79 methylation by Dot1 identified all known regulators as well as novel players and processes. These include histone deposition, homologous recombination, and adenosine kinase, which influences the methionine cycle. Gcn5, the acetyltransferase within the SAGA complex, was found to regulate histone methylation and H2B ubiquitination. The concept of Epi-ID is widely applicable and can be readily applied to other chromatin features. DOI:http://dx.doi.org/10.7554/eLife.18919.001 To fit into the nucleus of eukaryotic cells (which include plant, animal and yeast cells), DNA wraps around histone proteins to form a structure called chromatin. Histones can be modified by a variety of chemical tags, which affect how easily nearby DNA can be accessed by other molecules in the cell. These modifications therefore help to control the activity of the genes encoded in the DNA and other key processes such as DNA repair. If histone modifications are not regulated correctly, diseases such as cancer may result. Enzymes generally perform the actual modification, but there is another layer of regulation that controls the activity of these enzymes that not much is known about. The activity of an enzyme that performs a histone modification known as H3K79 methylation (which involves a methyl chemical group being added to a particular region of a particular histone protein) has been linked to some forms of leukemia. Collections of mutant yeast cells can be used to identify the factors that regulate histone modifications in both yeast and human cells. However, current methods that screen for these regulators are time consuming. To make the search for histone modification regulators more efficient, Vlaming et al. developed a new screening procedure called Epi-ID that can measure the amount of a specific histone modification in thousands of budding yeast mutants at the same time. In Epi-ID, each mutant yeast cell has a unique DNA sequence, or “barcode”. The mutant cells are mixed together and the barcodes that are modified by a particular histone modification – such as H3K79 methylation – are isolated and then counted using a DNA sequencing technique. A high barcode count of a certain mutant indicates that more of the histone modification occurs in that mutant. Using Epi-ID to survey H3K79 methylation enabled Vlaming et al. to successfully identify all previously known H3K79 methylation regulators, as well several new ones. These new regulators included enzymes that deposit histones on DNA, that carry out DNA repair, and that modify or de-modify histone proteins. To move forward with the newly identified regulators, it will be important to analyze how they control H3K79 methylation in yeast cells and to determine whether the regulators also control H3K79 methylation in human cells. Finally, Epi-ID can be used to identify regulators of other types of histone modifications. A better understanding of chromatin regulation – and H3K79 methylation regulation in particular – can increase our understanding of diseases in which chromatin is deregulated, and may yield new strategies for the treatment of such diseases. DOI:http://dx.doi.org/10.7554/eLife.18919.002
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Affiliation(s)
- Hanneke Vlaming
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Thom M Molenaar
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Tibor van Welsem
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
| | | | - Desiree E Smith
- Department of Clinical Chemistry, Metabolic Laboratory, VU University Medical Center, Amsterdam, Netherlands
| | - Arno Velds
- Central Genomics Facility, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Liesbeth Hoekman
- Mass Spectrometry/Proteomics Facility, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Tessy Korthout
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Sjoerd Hendriks
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
| | - A F Maarten Altelaar
- Mass Spectrometry/Proteomics Facility, Netherlands Cancer Institute, Amsterdam, Netherlands.,Biomolecular Mass Spectrometry and Proteomics, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, Netherlands
| | - Fred van Leeuwen
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, Netherlands
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Morgan MT, Wolberger C. Recognition of ubiquitinated nucleosomes. Curr Opin Struct Biol 2016; 42:75-82. [PMID: 27923209 DOI: 10.1016/j.sbi.2016.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/03/2016] [Accepted: 11/15/2016] [Indexed: 11/26/2022]
Abstract
Histone ubiquitination plays a non-degradative role in regulating transcription and the DNA damage response. A mechanistic understanding of this chromatin modification has lagged that of small histone modifications because of the technical challenges in preparing ubiquitinated nucleosomes. The recent structure of the DUB module of the SAGA coactivator complex bound to a nucleosome containing monoubiquitinated H2B has provided the first view of how specialized subunits target this enzyme to its substrate. Single particle electron microscopy of the intact SAGA coactivator suggests how the DUB module and histone acetyltransferase module engage a nucleosomal substrate. A cryo EM study of 53BP1 bound to nucleosomes containing ubiquitinated H2A and H4 methylated at K20 extends our understanding of recognition of biologically distinct combinations of chromatin marks through multivalent interactions.
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Affiliation(s)
- Michael T Morgan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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24
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Morgan MT, Haj-Yahya M, Ringel AE, Bandi P, Brik A, Wolberger C. Structural basis for histone H2B deubiquitination by the SAGA DUB module. Science 2016; 351:725-8. [PMID: 26912860 PMCID: PMC4863942 DOI: 10.1126/science.aac5681] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Monoubiquitinated histone H2B plays multiple roles in transcription activation. H2B is deubiquitinated by the Spt-Ada-Gcn5 acetyltransferase (SAGA) coactivator, which contains a four-protein subcomplex known as the deubiquitinating (DUB) module. The crystal structure of the Ubp8/Sgf11/Sus1/Sgf73 DUB module bound to a ubiquitinated nucleosome reveals that the DUB module primarily contacts H2A/H2B, with an arginine cluster on the Sgf11 zinc finger domain docking on the conserved H2A/H2B acidic patch. The Ubp8 catalytic domain mediates additional contacts with H2B, as well as with the conjugated ubiquitin. We find that the DUB module deubiquitinates H2B both in the context of the nucleosome and in H2A/H2B dimers complexed with the histone chaperone, FACT, suggesting that SAGA could target H2B at multiple stages of nucleosome disassembly and reassembly during transcription.
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Affiliation(s)
- Michael T Morgan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mahmood Haj-Yahya
- Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Alison E Ringel
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Prasanthi Bandi
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ashraf Brik
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200008, Israel
| | - Cynthia Wolberger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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25
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Abstract
Acetylation is a dynamic post-translational modification that is attached to protein substrates by lysine acetyltransferases (KATs) and removed by lysine deacetylases (KDACs). While these enzymes are best characterized as histone modifiers and regulators of gene transcription, work in a number of systems highlights that acetylation is a pervasive modification and suggests a broad scope for KAT and KDAC functions in the cell. As we move beyond generating lists of acetylated proteins, the acetylation field is in dire need of robust tools to connect acetylation and deacetylation machineries to their respective substrates and to dissect the function of individual sites. The Saccharomyces cerevisiae model system provides such a toolkit in the context of both tried and true genetic techniques and cutting-edge proteomic and cell imaging methods. Here, we review these methods in the context of their contributions to acetylation research thus far and suggest strategies for addressing lingering questions in the field.
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Setiaputra D, Ross JD, Lu S, Cheng DT, Dong MQ, Yip CK. Conformational flexibility and subunit arrangement of the modular yeast Spt-Ada-Gcn5 acetyltransferase complex. J Biol Chem 2015; 290:10057-70. [PMID: 25713136 DOI: 10.1074/jbc.m114.624684] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Indexed: 01/28/2023] Open
Abstract
The Spt-Ada-Gcn5 acetyltransferase (SAGA) complex is a highly conserved, 19-subunit histone acetyltransferase complex that activates transcription through acetylation and deubiquitination of nucleosomal histones in Saccharomyces cerevisiae. Because SAGA has been shown to display conformational variability, we applied gradient fixation to stabilize purified SAGA and systematically analyzed this flexibility using single-particle EM. Our two- and three-dimensional studies show that SAGA adopts three major conformations, and mutations of specific subunits affect the distribution among these. We also located the four functional modules of SAGA using electron microscopy-based labeling and transcriptional activator binding analyses and show that the acetyltransferase module is localized in the most mobile region of the complex. We further comprehensively mapped the subunit interconnectivity of SAGA using cross-linking mass spectrometry, revealing that the Spt and Taf subunits form the structural core of the complex. These results provide the necessary restraints for us to generate a model of the spatial arrangement of all SAGA subunits. According to this model, the chromatin-binding domains of SAGA are all clustered in one face of the complex that is highly flexible. Our results relate information of overall SAGA structure with detailed subunit level interactions, improving our understanding of its architecture and flexibility.
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Affiliation(s)
- Dheva Setiaputra
- From the Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - James D Ross
- From the Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Shan Lu
- the National Institute of Biological Sciences, Beijing 102206, China
| | - Derrick T Cheng
- From the Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Meng-Qiu Dong
- the National Institute of Biological Sciences, Beijing 102206, China
| | - Calvin K Yip
- From the Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
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