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Mondragón-Rosas F, Florencio-Martínez LE, Villa-Delavequia GS, Manning-Cela RG, Carrero JC, Nepomuceno-Mejía T, Martínez-Calvillo S. Characterization of Tau95 led to the identification of a four-subunit TFIIIC complex in trypanosomatid parasites. Appl Microbiol Biotechnol 2024; 108:109. [PMID: 38204130 PMCID: PMC10781861 DOI: 10.1007/s00253-023-12903-8] [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: 07/05/2023] [Revised: 09/20/2023] [Accepted: 09/30/2023] [Indexed: 01/12/2024]
Abstract
RNA polymerase III (RNAP III) synthetizes small essential non-coding RNA molecules such as tRNAs and 5S rRNA. In yeast and vertebrates, RNAP III needs general transcription factors TFIIIA, TFIIIB, and TFIIIC to initiate transcription. TFIIIC, composed of six subunits, binds to internal promoter elements in RNAP III-dependent genes. Limited information is available about RNAP III transcription in the trypanosomatid protozoa Trypanosoma brucei and Leishmania major, which diverged early from the eukaryotic lineage. Analyses of the first published draft of the trypanosomatid genome sequences failed to recognize orthologs of any of the TFIIIC subunits, suggesting that this transcription factor is absent in these parasites. However, a putative TFIIIC subunit was recently annotated in the databases. Here we characterize this subunit in T. brucei and L. major and demonstrate that it corresponds to Tau95. In silico analyses showed that both proteins possess the typical Tau95 sequences: the DNA binding region and the dimerization domain. As anticipated for a transcription factor, Tau95 localized to the nucleus in insect forms of both parasites. Chromatin immunoprecipitation (ChIP) assays demonstrated that Tau95 binds to tRNA and U2 snRNA genes in T. brucei. Remarkably, by performing tandem affinity purifications we identified orthologs of TFIIIC subunits Tau55, Tau131, and Tau138 in T. brucei and L. major. Thus, contrary to what was assumed, trypanosomatid parasites do possess a TFIIIC complex. Other putative interacting partners of Tau95 were identified in T. brucei and L. major. KEY POINTS: • A four-subunit TFIIIC complex is present in T. brucei and L. major • TbTau95 associates with tRNA and U2 snRNA genes • Putative interacting partners of Tau95 might include some RNAP II regulators.
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Affiliation(s)
- Fabiola Mondragón-Rosas
- Facultad de Estudios Superiores Iztacala, Unidad de Biomedicina, Universidad Nacional Autónoma de México, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Luis E Florencio-Martínez
- Facultad de Estudios Superiores Iztacala, Unidad de Biomedicina, Universidad Nacional Autónoma de México, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Gino S Villa-Delavequia
- Facultad de Estudios Superiores Iztacala, Unidad de Biomedicina, Universidad Nacional Autónoma de México, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Rebeca G Manning-Cela
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. IPN 2508, Ciudad de Mexico, CP 07360, México
| | - Julio C Carrero
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de Mexico, 04510, México
| | - Tomás Nepomuceno-Mejía
- Facultad de Estudios Superiores Iztacala, Unidad de Biomedicina, Universidad Nacional Autónoma de México, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México
| | - Santiago Martínez-Calvillo
- Facultad de Estudios Superiores Iztacala, Unidad de Biomedicina, Universidad Nacional Autónoma de México, Av. de los Barrios 1, Col. Los Reyes Iztacala, Tlalnepantla, Edo. de México, CP 54090, México.
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2
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Talyzina A, Han Y, Banerjee C, Fishbain S, Reyes A, Vafabakhsh R, He Y. Structural basis of TFIIIC-dependent RNA polymerase III transcription initiation. Mol Cell 2023; 83:2641-2652.e7. [PMID: 37402369 PMCID: PMC10528418 DOI: 10.1016/j.molcel.2023.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/02/2023] [Accepted: 06/08/2023] [Indexed: 07/06/2023]
Abstract
RNA polymerase III (Pol III) is responsible for transcribing 5S ribosomal RNA (5S rRNA), tRNAs, and other short non-coding RNAs. Its recruitment to the 5S rRNA promoter requires transcription factors TFIIIA, TFIIIC, and TFIIIB. Here, we use cryoelectron microscopy (cryo-EM) to visualize the S. cerevisiae complex of TFIIIA and TFIIIC bound to the promoter. Gene-specific factor TFIIIA interacts with DNA and acts as an adaptor for TFIIIC-promoter interactions. We also visualize DNA binding of TFIIIB subunits, Brf1 and TBP (TATA-box binding protein), which results in the full-length 5S rRNA gene wrapping around the complex. Our smFRET study reveals that the DNA within the complex undergoes both sharp bending and partial dissociation on a slow timescale, consistent with the model predicted from our cryo-EM results. Our findings provide new insights into the transcription initiation complex assembly on the 5S rRNA promoter and allow us to directly compare Pol III and Pol II transcription adaptations.
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Affiliation(s)
- Anna Talyzina
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - Yan Han
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Chiranjib Banerjee
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Susan Fishbain
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Alexis Reyes
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA; Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA; Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, USA.
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3
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Seifert-Davila W, Girbig M, Hauptmann L, Hoffmann T, Eustermann S, Müller CW. Structural insights into human TFIIIC promoter recognition. SCIENCE ADVANCES 2023; 9:eadh2019. [PMID: 37418517 DOI: 10.1126/sciadv.adh2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/02/2023] [Indexed: 07/09/2023]
Abstract
Transcription factor (TF) IIIC recruits RNA polymerase (Pol) III to most of its target genes. Recognition of intragenic A- and B-box motifs in transfer RNA (tRNA) genes by TFIIIC modules τA and τB is the first critical step for tRNA synthesis but is mechanistically poorly understood. Here, we report cryo-electron microscopy structures of the six-subunit human TFIIIC complex unbound and bound to a tRNA gene. The τB module recognizes the B-box via DNA shape and sequence readout through the assembly of multiple winged-helix domains. TFIIIC220 forms an integral part of both τA and τB connecting the two subcomplexes via a ~550-amino acid residue flexible linker. Our data provide a structural mechanism by which high-affinity B-box recognition anchors TFIIIC to promoter DNA and permits scanning for low-affinity A-boxes and TFIIIB for Pol III activation.
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Affiliation(s)
- Wolfram Seifert-Davila
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
- Candidate for joint PhD degree from EMBL and Faculty of Biosciences, Heidelberg University, 69120 Heidelberg, Germany
| | - Mathias Girbig
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Luis Hauptmann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Thomas Hoffmann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Sebastian Eustermann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Christoph W Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
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4
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Talyzina A, Han Y, Banerjee C, Fishbain S, Reyes A, Vafabakhsh R, He Y. Structural basis of TFIIIC-dependent RNA Polymerase III transcription initiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.16.540967. [PMID: 37292922 PMCID: PMC10245719 DOI: 10.1101/2023.05.16.540967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
RNA Polymerase III (Pol III) is responsible for transcribing 5S ribosomal RNA (5S rRNA), tRNAs, and other short non-coding RNAs. Its recruitment to the 5S rRNA promoter requires transcription factors TFIIIA, TFIIIC, and TFIIIB. Here we use cryo-electron microscopy to visualize the S. cerevisiae complex of TFIIIA and TFIIIC bound to the promoter. Brf1-TBP binding further stabilizes the DNA, resulting in the full-length 5S rRNA gene wrapping around the complex. Our smFRET study reveals that the DNA undergoes both sharp bending and partial dissociation on a slow timescale, consistent with the model predicted from our cryo-EM results. Our findings provide new insights into the mechanism of how the transcription initiation complex assembles on the 5S rRNA promoter, a crucial step in Pol III transcription regulation.
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Affiliation(s)
- Anna Talyzina
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, United States
| | - Yan Han
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
| | - Chiranjib Banerjee
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
| | - Susan Fishbain
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
| | - Alexis Reyes
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, United States
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, United States
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, United States
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, United States
- Lead contact
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5
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Szabó K, Miskei M, Farkas I, Dombrádi V. The phosphatome of opportunistic pathogen Candida species. FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2020.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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6
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Structure of the TFIIIC subcomplex τA provides insights into RNA polymerase III pre-initiation complex formation. Nat Commun 2020; 11:4905. [PMID: 32999288 PMCID: PMC7528018 DOI: 10.1038/s41467-020-18707-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 09/08/2020] [Indexed: 01/05/2023] Open
Abstract
Transcription factor (TF) IIIC is a conserved eukaryotic six-subunit protein complex with dual function. It serves as a general TF for most RNA polymerase (Pol) III genes by recruiting TFIIIB, but it is also involved in chromatin organization and regulation of Pol II genes through interaction with CTCF and condensin II. Here, we report the structure of the S. cerevisiae TFIIIC subcomplex τA, which contains the most conserved subunits of TFIIIC and is responsible for recruitment of TFIIIB and transcription start site (TSS) selection at Pol III genes. We show that τA binding to its promoter is auto-inhibited by a disordered acidic tail of subunit τ95. We further provide a negative-stain reconstruction of τA bound to the TFIIIB subunits Brf1 and TBP. This shows that a ruler element in τA achieves positioning of TFIIIB upstream of the TSS, and suggests remodeling of the complex during assembly of TFIIIB by TFIIIC.
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7
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Ciesla M, Skowronek E, Boguta M. Function of TFIIIC, RNA polymerase III initiation factor, in activation and repression of tRNA gene transcription. Nucleic Acids Res 2019; 46:9444-9455. [PMID: 30053100 PMCID: PMC6182151 DOI: 10.1093/nar/gky656] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/10/2018] [Indexed: 01/09/2023] Open
Abstract
Transcription of transfer RNA genes by RNA polymerase III (Pol III) is controlled by general factors, TFIIIB and TFIIIC, and a negative regulator, Maf1. Here we report the interplay between TFIIIC and Maf1 in controlling Pol III activity upon the physiological switch of yeast from fermentation to respiration. TFIIIC directly competes with Pol III for chromatin occupancy as demonstrated by inversely correlated tDNA binding. The association of TFIIIC with tDNA was stronger under unfavorable respiratory conditions and in the presence of Maf1. Induction of tDNA transcription by glucose-activated protein kinase A (PKA) was correlated with the down-regulation of TFIIIC occupancy on tDNA. The conditions that activate the PKA signaling pathway promoted the binding of TFIIIB subunits, Brf1 and Bdp1, with tDNA, but decreased their interaction with TFIIIC. Association of Brf1 and Bdp1 with TFIIIC was much stronger under repressive conditions, potentially restricting TFIIIB recruitment to tDNA and preventing Pol III recruitment. Altogether, we propose a model in which, depending on growth conditions, TFIIIC promotes activation or repression of tDNA transcription.
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Affiliation(s)
- Malgorzata Ciesla
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Ewa Skowronek
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
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8
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Khatter H, Vorländer MK, Müller CW. RNA polymerase I and III: similar yet unique. Curr Opin Struct Biol 2017; 47:88-94. [PMID: 28743025 DOI: 10.1016/j.sbi.2017.05.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/22/2017] [Indexed: 01/03/2023]
Abstract
The majority of non-protein-coding RNAs present in eukaryotic cells comprises rRNAs, tRNAs and U6 snRNA that are involved in protein biosynthesis and are synthesized by DNA-dependent-RNA polymerase I and III. The transcription cycle (initiation, elongation and termination) has similar principles in all three nuclear RNA polymerases with specific features that are reflected back in their structures. Recently, owing to the 'resolution revolution' in electron cryo-microscopy, there has been a significant advancement in the understanding of these molecular machines. Here, we highlight the structure-function adaptation in specificity and activity of these molecular machines and present parallels and distinctions between their transcription mechanisms.
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Affiliation(s)
- Heena Khatter
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Matthias K Vorländer
- 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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9
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Architecture of TFIIIC and its role in RNA polymerase III pre-initiation complex assembly. Nat Commun 2015; 6:7387. [PMID: 26060179 PMCID: PMC4490372 DOI: 10.1038/ncomms8387] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/04/2015] [Indexed: 02/05/2023] Open
Abstract
In eukaryotes, RNA Polymerase III (Pol III) is specifically responsible for transcribing genes encoding tRNAs and other short non-coding RNAs. The recruitment of Pol III to tRNA-encoding genes requires the transcription factors (TF) IIIB and IIIC. TFIIIC has been described as a conserved, multi-subunit protein complex composed of two subcomplexes, called τA and τB. How these two subcomplexes are linked and how their interaction affects the formation of the Pol III pre-initiation complex (PIC) is poorly understood. Here we use chemical crosslinking mass spectrometry and determine the molecular architecture of TFIIIC. We further report the crystal structure of the essential TPR array from τA subunit τ131 and characterize its interaction with a central region of τB subunit τ138. The identified τ131–τ138 interacting region is essential in vivo and overlaps with TFIIIB-binding sites, revealing a crucial interaction platform for the regulation of tRNA transcription initiation. TFIIIC is a RNA polymerase III-specific general transcription factor complex essential for tRNA synthesis. Here the authors combine chemical crosslinking/mass spectrometry and X-ray crystallography to define the architecture of TFIIIC and suggest a model for the assembly of pre-initiation complexes at tRNA genes.
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10
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Moreno-Morcillo M, Taylor NMI, Gruene T, Legrand P, Rashid UJ, Ruiz FM, Steuerwald U, Müller CW, Fernández-Tornero C. Solving the RNA polymerase I structural puzzle. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2570-82. [PMID: 25286842 PMCID: PMC4188003 DOI: 10.1107/s1399004714015788] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 07/06/2014] [Indexed: 11/28/2022]
Abstract
Knowing the structure of multi-subunit complexes is critical to understand basic cellular functions. However, when crystals of these complexes can be obtained they rarely diffract beyond 3 Å resolution, which complicates X-ray structure determination and refinement. The crystal structure of RNA polymerase I, an essential cellular machine that synthesizes the precursor of ribosomal RNA in the nucleolus of eukaryotic cells, has recently been solved. Here, the crucial steps that were undertaken to build the atomic model of this multi-subunit enzyme are reported, emphasizing how simple crystallographic experiments can be used to extract relevant biological information. In particular, this report discusses the combination of poor molecular replacement and experimental phases, the application of multi-crystal averaging and the use of anomalous scatterers as sequence markers to guide tracing and to locate the active site. The methods outlined here will likely serve as a reference for future structural determination of large complexes at low resolution.
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Affiliation(s)
- María Moreno-Morcillo
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Nicholas M. I. Taylor
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Tim Gruene
- Department of Structural Chemistry, Georg-August-University, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Pierre Legrand
- SOLEIL Synchrotron, L’Orme de Merisiers, Saint Aubin, Gif-sur-Yvette, France
| | - Umar J. Rashid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Federico M. Ruiz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Ulrich Steuerwald
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Christoph W. Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Carlos Fernández-Tornero
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain
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Taylor NMI, Baudin F, von Scheven G, Müller CW. RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74. Nucleic Acids Res 2013; 41:9183-96. [PMID: 23921640 PMCID: PMC3799434 DOI: 10.1093/nar/gkt664] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Transcription of tRNA-encoding genes by RNA polymerase (Pol) III requires the six-subunit general transcription factor IIIC that uses subcomplexes τA and τB to recognize two gene-internal promoter elements named A- and B-box. The Schizosaccharomyces pombe τA subcomplex comprises subunits Sfc1, Sfc4 and Sfc7. The crystal structure of the Sfc1/Sfc7 heterodimer reveals similar domains and overall domain architecture to the Pol II-specific general transcription factor TFIIF Rap30/Rap74. The N-terminal Sfc1/Sfc7 dimerization module consists of a triple β-barrel similar to the N-terminal TFIIF Rap30/Rap74 dimerization module, whereas the C-terminal Sfc1 DNA-binding domain contains a winged-helix domain most similar to the TFIIF Rap30 C-terminal winged-helix domain. Sfc1 DNA-binding domain recognizes single and double-stranded DNA by an unknown mechanism. Several features observed for A-box recognition by τA resemble the recognition of promoters by bacterial RNA polymerase, where σ factor unfolds double-stranded DNA and stabilizes the non-coding DNA strand in an open conformation. Such a function has also been proposed for TFIIF, suggesting that the observed structural similarity between Sfc1/Sfc7 and TFIIF Rap30/Rap74 might also reflect similar functions.
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Affiliation(s)
- Nicholas M I Taylor
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany and UJF-EMBL-CNRS UMI 3265, Unit of Virus Host-Cell Interactions, 38042 Grenoble Cedex 9, France
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