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Organization and regulation of gene transcription. Nature 2019; 573:45-54. [PMID: 31462772 DOI: 10.1038/s41586-019-1517-4] [Citation(s) in RCA: 361] [Impact Index Per Article: 72.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/30/2019] [Indexed: 12/18/2022]
Abstract
The regulated transcription of genes determines cell identity and function. Recent structural studies have elucidated mechanisms that govern the regulation of transcription by RNA polymerases during the initiation and elongation phases. Microscopy studies have revealed that transcription involves the condensation of factors in the cell nucleus. A model is emerging for the transcription of protein-coding genes in which distinct transient condensates form at gene promoters and in gene bodies to concentrate the factors required for transcription initiation and elongation, respectively. The transcribing enzyme RNA polymerase II may shuttle between these condensates in a phosphorylation-dependent manner. Molecular principles are being defined that rationalize transcriptional organization and regulation, and that will guide future investigations.
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Jackobel AJ, Han Y, He Y, Knutson BA. Breaking the mold: structures of the RNA polymerase I transcription complex reveal a new path for initiation. Transcription 2018; 9:255-261. [PMID: 29264963 PMCID: PMC6104693 DOI: 10.1080/21541264.2017.1416268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
While structures of the RNA polymerase (Pol) II initiation complex have been resolved and extensively studied, the Pol I initiation complex remained elusive. Here, we review the recent structural analyses of the yeast Pol I transcription initiation complex that reveal several unique and unexpected Pol I-specific properties.
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Affiliation(s)
- Ashleigh J. Jackobel
- SUNY Upstate Medical University, Department of Biochemistry and Molecular Biology, 750 East Adams Street, Syracuse, NY 13210
| | - Yan Han
- Northwestern University, Department of Molecular Biosciences, 2205 Tech Drive, Evanston, IL 60208
| | - Yuan He
- Northwestern University, Department of Molecular Biosciences, 2205 Tech Drive, Evanston, IL 60208
| | - Bruce A. Knutson
- SUNY Upstate Medical University, Department of Biochemistry and Molecular Biology, 750 East Adams Street, Syracuse, NY 13210,Bruce A. Knutson , SUNY Upstate Medical University, Department of Biochemistry and Molecular Biology, 750 East Adams Street, Syracuse, NY 13210, USA
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3
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Han Y, Yan C, Nguyen THD, Jackobel AJ, Ivanov I, Knutson BA, He Y. Structural mechanism of ATP-independent transcription initiation by RNA polymerase I. eLife 2017; 6:e27414. [PMID: 28623663 PMCID: PMC5489313 DOI: 10.7554/elife.27414] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/17/2017] [Indexed: 12/02/2022] Open
Abstract
Transcription initiation by RNA Polymerase I (Pol I) depends on the Core Factor (CF) complex to recognize the upstream promoter and assemble into a Pre-Initiation Complex (PIC). Here, we solve a structure of Saccharomyces cerevisiae Pol I-CF-DNA to 3.8 Å resolution using single-particle cryo-electron microscopy. The structure reveals a bipartite architecture of Core Factor and its recognition of the promoter from -27 to -16. Core Factor's intrinsic mobility correlates well with different conformational states of the Pol I cleft, in addition to the stabilization of either Rrn7 N-terminal domain near Pol I wall or the tandem winged helix domain of A49 at a partially overlapping location. Comparison of the three states in this study with the Pol II system suggests that a ratchet motion of the Core Factor-DNA sub-complex at upstream facilitates promoter melting in an ATP-independent manner, distinct from a DNA translocase actively threading the downstream DNA in the Pol II PIC.
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Affiliation(s)
- Yan Han
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Chunli Yan
- Department of Chemistry, Georgia State University, Atlanta, United States,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, United States
| | | | - Ashleigh J Jackobel
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, United States
| | - Ivaylo Ivanov
- Department of Chemistry, Georgia State University, Atlanta, United States,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, United States
| | - Bruce A Knutson
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, United States, (BAK)
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, United States, (YHe)
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4
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The use of diethyl pyrocarbonate and potassium permanganate as probes for strand separation and structural distortions in DNA. Methods Mol Biol 2009; 543:73-85. [PMID: 19378160 DOI: 10.1007/978-1-60327-015-1_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Diethyl pyrocarbonate (DEPC) and potassium permanganate are useful reagents for detecting DNA distortions, especially melted regions. Unlike most other footprinting methods, these reagents can detect such distortions even within the regions of protein-DNA complexes normally protected in other footprinting techniques. Further, reactions are very robust, so that distorted regions can be detected even under conditions where efficiency of DNA-protein complex formation is not high. DEPC reacts with bases that are fully or partially unstacked in DNA, in the preferential order adenosine > guanine >> cytosine. Permanganate reacts strongly with thymine in unstacked regions of DNA, and exhibits only very weak reaction with guanine, cytosine, or adenine. The combination of both reagents gives excellent coverage of all sequence regions of DNA. Because reaction requires unstacking, the two reagents detect both melted regions and regions that are unstacked because of other distortions such as bending. Permanganate has the additional advantage that it can be utilized in living cells.
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Iben S, Tschochner H, Bier M, Hoogstraten D, Hozák P, Egly JM, Grummt I. TFIIH plays an essential role in RNA polymerase I transcription. Cell 2002; 109:297-306. [PMID: 12015980 DOI: 10.1016/s0092-8674(02)00729-8] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TFIIH is a multisubunit protein complex that plays an essential role in nucleotide excision repair and transcription of protein-coding genes. Here, we report that TFIIH is also required for ribosomal RNA synthesis in vivo and in vitro. In yeast, pre-rRNA synthesis is impaired in TFIIH ts strains. In a mouse, part of cellular TFIIH is localized within the nucleolus and is associated with subpopulations of both RNA polymerase I and the basal factor TIF-IB. Transcription systems lacking TFIIH are inactive and exogenous TFIIH restores transcriptional activity. TFIIH is required for productive but not abortive rDNA transcription, implying a postinitiation role in transcription. The results provide a molecular link between RNA polymerase I transcription and transcription-coupled repair of active ribosomal RNA genes.
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Affiliation(s)
- Sebastian Iben
- Division of Molecular Biology of the Cell II, German Cancer Research Center, D-69120, Heidelberg, Germany
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6
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Al-Khouri AM, Paule MR. A novel RNA polymerase I transcription initiation factor, TIF-IE, commits rRNA genes by interaction with TIF-IB, not by DNA binding. Mol Cell Biol 2002; 22:750-61. [PMID: 11784852 PMCID: PMC133551 DOI: 10.1128/mcb.22.3.750-761.2002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the small, free-living amoeba Acanthamoeba castellanii, rRNA transcription requires, in addition to RNA polymerase I, a single DNA-binding factor, transcription initiation factor IB (TIF-IB). TIF-IB is a multimeric protein that contains TATA-binding protein (TBP) and four TBP-associated factors that are specific for polymerase I transcription. TIF-IB is required for accurate and promoter-specific initiation of rRNA transcription, recruiting and positioning the polymerase on the start site by protein-protein interaction. In A. castellanii, partially purified TIF-IB can form a persistent complex with the ribosomal DNA (rDNA) promoter while homogeneous TIF-IB cannot. An additional factor, TIF-IE, is required along with homogeneous TIF-IB for the formation of a stable complex on the rDNA core promoter. We show that TIF-IE by itself, however, does not bind to the rDNA promoter and thus differs in its mechanism from the upstream binding factor and upstream activating factor, which carry out similar complex-stabilizing functions in vertebrates and yeast, respectively. In addition to its presence in impure TIF-IB, TIF-IE is found in highly purified fractions of polymerase I, with which it associates. Renaturation of polypeptides excised from sodium dodecyl sulfate-polyacrylamide gels showed that a 141-kDa polypeptide possesses all the known activities of TIF-IE.
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Affiliation(s)
- Anna Maria Al-Khouri
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA
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7
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Saez-Vasquez J, Meissner M, Pikaard CS. RNA polymerase I holoenzyme-promoter complexes include an associated CK2-like protein kinase. PLANT MOLECULAR BIOLOGY 2001; 47:449-459. [PMID: 11587515 DOI: 10.1023/a:1011619413393] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In eukaryotes, RNA polymerase I (pol I) transcribes the tandemly repeated genes that encode the precursor of 18S, 5.8S and 25S ribosomal RNAs. In plants and animals, the pol I enzyme can be purified in a holoenzyme form that is self-sufficient for promoter binding and accurate, promoter-dependent transcription in a cell-free system. In this report, we show that a casein kinase 2 (CK2)-like protein kinase co-purifies with pol I holoenzyme activity purified from broccoli (Brassica oleracea). Using an immobilized template assay, we show that the CK2-like activity is part of the protein-DNA complex that results upon binding of the holoenzyme to the rRNA gene promoter. The CK2 activity phosphorylates a similar set of holoenzyme proteins both before and after promoter binding. These data provide further evidence that pol I holoenzyme activity can be attributed to a single, multi-protein complex self-sufficient for promoter association and accurate, promoter-dependent transcription.
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Affiliation(s)
- J Saez-Vasquez
- Biology Department, Washington University, St. Louis, MO, 63130, USA
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Guo Y, Lew CM, Gralla JD. Promoter opening by sigma(54) and sigma(70) RNA polymerases: sigma factor-directed alterations in the mechanism and tightness of control. Genes Dev 2000; 14:2242-55. [PMID: 10970887 PMCID: PMC316896 DOI: 10.1101/gad.794800] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transcription control at the melting step is not yet understood. Here, band shift, cross-linking, and transcription experiments on diverse DNA probes were used with two bacterial RNA polymerase holoenzymes that differ in how they regulate melting. Data indicated that both sigma(54) and sigma(70) holoenzymes assume a default closed form that cannot establish single-strand binding. Upon activation the enzymes are converted to an open form that can bind simultaneously to the upstream fork junction and to the melted transcription start site. The key difference is that sigma(54) imposes tighter regulation by creating a complex molecular switch at -12/-11; the current data show that this switch can be thrown by activator. In this case an ATP-bound enhancer protein causes sigma(54) to alter its cross-linking pattern near -11 and also causes a reorganization of holoenzyme: DNA interactions, detected by electrophoretic mobility-shift assay. At a temperature-dependent sigma(70) promoter, elevated temperature alone can assist in triggering conformational changes that enhance the engagement of single-strand DNA. Thus, the two sigma factors modify the same intrinsic opening pathway to create quite different mechanisms of transcriptional regulation.
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Affiliation(s)
- Y Guo
- Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, California 90095, USA
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9
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Abstract
Ribosomal RNA transcription initiation requires the melting of DNA to form an open complex, formation of the first few phosphodiester bonds, commencement of RNA polymerase I movement along the DNA, clearance of the promoter, and the formation of a steady-state ternary elongation complex. We examined DNA melting and promoter clearance by using potassium permanganate, diethylpyrocarbonate and methidiumpropylEDTA.Fe(II) footprinting. In combination, these methods demonstrated: (1) TIF-IB and RNA polymerase I are the only proteins required for formation of an initial approximately 9 base-pair open promoter region. This finding contradicts earlier results using diethylpyrocarbonate alone, which suggested an RNA synthesis requirement for stable melting. (2) DNA melting is temperature-dependent, with a tm between 15 and 20 degrees C. (3) Temperature-dependency of melting, as well as stalling the polymerase at sites close to the transcription start site revealed that the melted DNA region initially opens upstream of the transcription initiation site, and enlarges in a downstream direction coordinate with initiation, eventually attaining a steady-state transcription bubble of approximately 19 base-pairs. (4) The RNA-DNA hybrid protects the template DNA from single-strand footprinting reagents. The hybrid is 9 bp in length, consistent with the longer hybrid estimated by some for the Escherichia coli polymerase and with the hybrids estimated for eukaryotic polymerases II and III.
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Affiliation(s)
- B F Kahl
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523-1870, USA
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10
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Abstract
The task of transcribing nuclear genes is shared between three RNA polymerases in eukaryotes: RNA polymerase (pol) I synthesizes the large rRNA, pol II synthesizes mRNA and pol III synthesizes tRNA and 5S rRNA. Although pol II has received most attention, pol I and pol III are together responsible for the bulk of transcriptional activity. This survey will summarise what is known about the process of transcription by pol I and pol III, how it happens and the proteins involved. Attention will be drawn to the similarities between the three nuclear RNA polymerase systems and also to their differences.
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Affiliation(s)
- M R Paule
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
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11
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Albert AC, Denton M, Kermekchiev M, Pikaard CS. Histone acetyltransferase and protein kinase activities copurify with a putative Xenopus RNA polymerase I holoenzyme self-sufficient for promoter-dependent transcription. Mol Cell Biol 1999; 19:796-806. [PMID: 9858602 PMCID: PMC83936 DOI: 10.1128/mcb.19.1.796] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mounting evidence suggests that eukaryotic RNA polymerases preassociate with multiple transcription factors in the absence of DNA, forming RNA polymerase holoenzyme complexes. We have purified an apparent RNA polymerase I (Pol I) holoenzyme from Xenopus laevis cells by sequential chromatography on five columns: DEAE-Sepharose, Biorex 70, Sephacryl S300, Mono Q, and DNA-cellulose. Single fractions from every column programmed accurate promoter-dependent transcription. Upon gel filtration chromatography, the Pol I holoenzyme elutes at a position overlapping the peak of Blue Dextran, suggesting a molecular mass in the range of approximately 2 MDa. Consistent with its large mass, Coomassie blue-stained sodium dodecyl sulfate-polyacrylamide gels reveal approximately 55 proteins in fractions purified to near homogeneity. Western blotting shows that TATA-binding protein precisely copurifies with holoenzyme activity, whereas the abundant Pol I transactivator upstream binding factor does not. Also copurifying with the holoenzyme are casein kinase II and a histone acetyltransferase activity with a substrate preference for histone H3. These results extend to Pol I the suggestion that signal transduction and chromatin-modifying activities are associated with eukaryotic RNA polymerases.
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Affiliation(s)
- A C Albert
- Biology Department, Washington University, St. Louis, Missouri 63130, USA
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12
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Radebaugh CA, Kubaska WM, Hoffman LH, Stiffler K, Paule MR. A novel transcription initiation factor (TIF), TIF-IE, is required for homogeneous Acanthamoeba castellanii TIF-IB (SL1) to form a committed complex. J Biol Chem 1998; 273:27708-15. [PMID: 9765308 DOI: 10.1074/jbc.273.42.27708] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The fundamental transcription initiation factor (TIF) for ribosomal RNA expression by eukaryotic RNA polymerase I, TIF-IB, has been purified to near homogeneity from Acanthamoeba castellanii using standard techniques. The purified factor consists of the TATA-binding protein and four TATA-binding protein-associated factors with relative molecular weights of 145,000, 99,000, 96,000, and 91,000. This yields a calculated native molecular weight of 460, 000, which compares well with its mass determined by scanning transmission electron microscopy (493,000) and its sedimentation rate, which is close to RNA polymerase I (515,000). Both impure and nearly homogeneous TIF-IB exhibit an apparent equilibrium dissociation constant of 56 +/- 3 pM. However, although impure TIF-IB can form a promoter-DNA complex resistant to challenge by other promoter-containing DNAs, near homogeneous TIF-IB cannot do so. An additional transcription factor, dubbed TIF-IE, restores the ability of near homogeneous TIF-IB to sequester DNA into a committed complex.
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Affiliation(s)
- C A Radebaugh
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA
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13
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Holstege FC, Timmers HT. Analysis of open complex formation during RNA polymerase II transcription initiation using heteroduplex templates and potassium permanganate probing. Methods 1997; 12:203-11. [PMID: 9237164 DOI: 10.1006/meth.1997.0472] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Open complex formation precedes initiation of transcription by RNA polymerases. In the analysis of transcription initiation from eukaryotic class II promoters, we have used promoter DNA structures that represent intermediates in open complex formation. We describe the preparation and isolation of heteroduplex promoter fragments. Probes containing these DNA structures have a general application in the study of proteins binding to junctions of double- and single-stranded DNA. Such proteins play important roles not only in the regulation of RNA synthesis but also in processes like repair, replication, and recombination of DNA. In addition, a protocol is provided for a rapid and quantitative assay for open complexes and transcription bubbles using potassium permanganate as a chemical probe for single-stranded regions in DNA.
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Affiliation(s)
- F C Holstege
- Laboratory for Physiological Chemistry, Utrecht University, The Netherlands
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Holstege FC, van der Vliet PC, Timmers HT. Opening of an RNA polymerase II promoter occurs in two distinct steps and requires the basal transcription factors IIE and IIH. EMBO J 1996; 15:1666-77. [PMID: 8612591 PMCID: PMC450078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have studied promoter opening in assays reconstituted with purified RNA polymerase II and basal transcription factors. We found that creating a region of heteroduplex DNA around the start site of the adenovirus major late (AdML) promoter circumvents the requirement for TFIIE and TFIIH in transcription. The critical size and position of the heteroduplex region that alleviates the requirement for TFIIE and TFIIH is six nucleotides, from -4 to +2. Promoter opening was investigated directly with potassium permanganate (KMnO4), a chemical probe specific for single-stranded thymidines. We found that KMnO4-detectable opening of the AdML promoter requires the presence of the complete pre-initiation complex, DBpolFEH, and that opening occurs in two discrete steps. First, dependent on ATP but prior to initiation, the -9 to +1 region becomes single-stranded. Second, formation of the first phosphodiester bond results in expansion of the open region to the +8 position. Our results lead to a model in which the critical function of the TFIIH-associated DNA helicases is to create a single-stranded region. This gives RNA polymerase II access to the nucleotides of the template strand and allows expansion of the open region upon formation of the first phosphodiester bond.
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Affiliation(s)
- F C Holstege
- Laboratory for Physiological Chemistry, Utrecht University, The Netherlands
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Geiduschek EP, Kassavetis GA. Comparing transcriptional initiation by RNA polymerases I and III. Curr Opin Cell Biol 1995; 7:344-51. [PMID: 7662364 DOI: 10.1016/0955-0674(95)80089-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We comment on the current understanding of transcriptional initiation by RNA polymerases I and III, and look for common modes of operation of these enzymes, emphasizing selected recent developments. These include definitive experiments on the constitution of the human RNA polymerase I transcription factor SL1/TIF-IB, the development of a genetic system for analyzing the function of RNA polymerase I in yeast, the elucidation of the structure of the human snRNA gene transcription factor SNAPc, and initial stages of mapping the protein-protein interactions involved in the assembly of transcriptional initiation complexes.
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Affiliation(s)
- E P Geiduschek
- Department of Biology, University of California at San Diego, La Jolla 92093-0634, USA
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Moss T, Stefanovsky VY. Promotion and regulation of ribosomal transcription in eukaryotes by RNA polymerase I. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1995; 50:25-66. [PMID: 7754036 DOI: 10.1016/s0079-6603(08)60810-7] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- T Moss
- Cancer Research Centre, Laval University, Hôtel-Dieu de Québec, Canada
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17
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Tantin D, Carey M. A heteroduplex template circumvents the energetic requirement for ATP during activated transcription by RNA polymerase II. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32452-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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18
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Identification of two steps during Xenopus ribosomal gene transcription that are sensitive to protein phosphorylation. Mol Cell Biol 1994. [PMID: 8114732 DOI: 10.1128/mcb.14.3.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein kinase(s) and protein phosphatase(s) present in a Xenopus S-100 transcription extract strongly influence promoter-dependent transcription by RNA polymerase I. The protein kinase inhibitor 6-dimethyl-aminopurine causes transcription to increase, while the protein phosphatase inhibitor okadaic acid causes transcription to decrease. Repression is also observed with inhibitor 2, and the addition of extra protein phosphatase 1 stimulates transcription, indicating that the endogenous phosphatase is a type 1 enzyme. Partial fractionation of the system, single-round transcription reactions, and kinetic experiments show that two different steps during ribosomal gene transcription are sensitive to protein phosphorylation: okadaic acid affects a step before or during transcription initiation, while 6-dimethylaminopurine stimulates a process "late" in the reaction, possibly reinitiation. The present results are a clear demonstration that transcription by RNA polymerase I can be regulated by protein phosphorylation.
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19
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Labhart P. Identification of two steps during Xenopus ribosomal gene transcription that are sensitive to protein phosphorylation. Mol Cell Biol 1994; 14:2011-20. [PMID: 8114732 PMCID: PMC358561 DOI: 10.1128/mcb.14.3.2011-2020.1994] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Protein kinase(s) and protein phosphatase(s) present in a Xenopus S-100 transcription extract strongly influence promoter-dependent transcription by RNA polymerase I. The protein kinase inhibitor 6-dimethyl-aminopurine causes transcription to increase, while the protein phosphatase inhibitor okadaic acid causes transcription to decrease. Repression is also observed with inhibitor 2, and the addition of extra protein phosphatase 1 stimulates transcription, indicating that the endogenous phosphatase is a type 1 enzyme. Partial fractionation of the system, single-round transcription reactions, and kinetic experiments show that two different steps during ribosomal gene transcription are sensitive to protein phosphorylation: okadaic acid affects a step before or during transcription initiation, while 6-dimethylaminopurine stimulates a process "late" in the reaction, possibly reinitiation. The present results are a clear demonstration that transcription by RNA polymerase I can be regulated by protein phosphorylation.
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Affiliation(s)
- P Labhart
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037
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