scholarly journals Factor C*, the specific initiation component of the mouse RNA polymerase I holoenzyme, is inactivated early in the transcription process.

1994 ◽  
Vol 14 (7) ◽  
pp. 5010-5021 ◽  
Author(s):  
R P Brun ◽  
K Ryan ◽  
B Sollner-Webb
Keyword(s):  
Rna Polymerase ◽  
Critical Distance ◽  
Rna Polymerase I ◽  
Rrna Gene ◽  
Rdna Transcription ◽  
Transcription Process ◽  
Factor C ◽  
Polymerase I

Factor C* is the component of the RNA polymerase I holoenzyme (factor C) that allows specific transcriptional initiation on a factor D (SL1)- and UBF-activated rRNA gene promoter. The in vitro transcriptional capacity of a preincubated rDNA promoter complex becomes exhausted very rapidly upon initiation of transcription. This is due to the rapid depletion of C* activity. In contrast, C* activity is not unstable in the absence of transcription, even in the presence of nucleoside triphosphates (NTPs). By using 3'dNTPs to specifically halt elongation, C* is seen to remain active through transcription complex assembly, initiation, and the first approximately 37 nucleotides of elongation, but it is inactivated before synthesis proceeds beyond approximately 40 nucleotides. When elongation is halted before this critical distance, the C* remains active and on that template complex, greatly extending the kinetics of transcription and generating manyfold more transcripts than would have been synthesized if elongation had proceeded past the critical distance where C* is inactivated. In complementary in vivo analysis under conditions where C* activity is not replenished, C* activity becomes depleted from cells, but this also occurs only when there is ongoing rDNA transcription. Thus, both in vitro and in vivo, the specific initiation-conferring component of the RNA polymerase I holoenzyme is used stoichiometrically in the transcription process.

Factor C*, the specific initiation component of the mouse RNA polymerase I holoenzyme, is inactivated early in the transcription process

1994 ◽  
Vol 14 (7) ◽  
pp. 5010-5021
Author(s):  
R P Brun ◽  
K Ryan ◽  
B Sollner-Webb
Keyword(s):  
Rna Polymerase ◽  
Critical Distance ◽  
Rna Polymerase I ◽  
Rrna Gene ◽  
Rdna Transcription ◽  
Transcription Process ◽  
Factor C ◽  
Polymerase I

Factor C* is the component of the RNA polymerase I holoenzyme (factor C) that allows specific transcriptional initiation on a factor D (SL1)- and UBF-activated rRNA gene promoter. The in vitro transcriptional capacity of a preincubated rDNA promoter complex becomes exhausted very rapidly upon initiation of transcription. This is due to the rapid depletion of C* activity. In contrast, C* activity is not unstable in the absence of transcription, even in the presence of nucleoside triphosphates (NTPs). By using 3'dNTPs to specifically halt elongation, C* is seen to remain active through transcription complex assembly, initiation, and the first approximately 37 nucleotides of elongation, but it is inactivated before synthesis proceeds beyond approximately 40 nucleotides. When elongation is halted before this critical distance, the C* remains active and on that template complex, greatly extending the kinetics of transcription and generating manyfold more transcripts than would have been synthesized if elongation had proceeded past the critical distance where C* is inactivated. In complementary in vivo analysis under conditions where C* activity is not replenished, C* activity becomes depleted from cells, but this also occurs only when there is ongoing rDNA transcription. Thus, both in vitro and in vivo, the specific initiation-conferring component of the RNA polymerase I holoenzyme is used stoichiometrically in the transcription process.

scholarly journals Recruitment of the Nucleolar Remodeling Complex NoRC Establishes Ribosomal DNA Silencing in Chromatin

2004 ◽  
Vol 24 (4) ◽  
pp. 1791-1798 ◽  
Author(s):  
Ralf Strohner ◽  
Attila Németh ◽  
Karl P. Nightingale ◽  
Ingrid Grummt ◽  
Peter B. Becker ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Ribosomal Dna ◽  
Active Role ◽  
Rna Polymerase I ◽  
In Vivo Studies ◽  
Rrna Gene ◽  
Rdna Transcription ◽  
Transcription Terminator ◽  
Polymerase I

ABSTRACT The rRNA gene cluster consists of multiple transcription units. Half of these are active, while the other half are transcriptionally inactive. Previously, in vivo studies have demonstrated that silencing of ribosomal DNA (rDNA) is mediated by the chromatin remodeling NoRC (nucleolar remodeling complex). To explore the mechanisms underlying NoRC-directed silencing of rDNA transcription, we investigated the effect of recombinant NoRC on RNA polymerase I transcription on reconstituted chromatin templates. We show that NoRC interacts with the transcription terminator factor (TTF-I), and this interaction is required both for the binding of TTF-I to its promoter-proximal target site and for the recruitment of NoRC to the promoter. After association with the rDNA promoter, NoRC alters the position of the promoter-bound nucleosome, thereby repressing RNA polymerase I transcription. This NoRC-directed rDNA repression requires the N terminus of histone H4. Repression is effective before preinitiation complex formation and as such is unable to exert an effect upon activated rDNA genes. Furthermore, the early steps of rDNA repression do not depend on DNA and histone modifications. These results reveal an important role for TTF-I in recruiting NoRC to rDNA and an active role for NoRC in the establishment of rDNA silencing.

scholarly journals Species-specific rDNA transcription is due to promoter-specific binding factors.

1984 ◽  
Vol 4 (2) ◽  
pp. 221-227 ◽  
Author(s):  
R Miesfeld ◽  
N Arnheim
Keyword(s):  
Rna Polymerase ◽  
Transcriptional Control ◽  
Specific Binding ◽  
Rna Polymerase I ◽  
Rdna Transcription ◽  
Nucleolar Dominance ◽  
Cell Extracts ◽  
Species Specific ◽  
Polymerase I

RNA polymerase I transcription factors were purified from HeLa and mouse L cell extracts by phosphocellulose chromatography. Three fractions from each species were found to be required for transcription. One of these fractions, virtually devoid of RNA polymerase I activity, was found to form a stable preinitiation complex with small DNA fragments containing promoter sequences from the homologous but not the heterologous species. These species-specific DNA-binding factors can explain nucleolar dominance in vivo in mouse-human hybrid somatic cells and species specificity in cell-free, RNA polymerase I-dependent transcription systems. The evolution of species-specific transcriptional control signals may be the natural outcome of a special relationship that exists between the RNA polymerase I transcription machinery and the multigene family coding for rRNA.

scholarly journals Stimulation of the mouse rRNA gene promoter by a distal spacer promoter.

1995 ◽  
Vol 15 (8) ◽  
pp. 4648-4656 ◽  
Author(s):  
M H Paalman ◽  
S L Henderson ◽  
B Sollner-Webb
Keyword(s):  
Rna Polymerase ◽  
Gene Promoter ◽  
Rna Polymerase I ◽  
Rrna Gene ◽  
Transcriptional Terminator ◽  
Wide Range ◽  
Polymerase I ◽  
Enhancer Sequences ◽  
Stimulation Of

We show that the mouse ribosomal DNA (rDNA) spacer promoter acts in vivo to stimulate transcription from a downstream rRNA gene promoter. This augmentation of mammalian RNA polymerase I transcription is observed in transient-transfection experiments with three different rodent cell lines, under noncompetitive as well as competitive transcription conditions, over a wide range of template concentrations, whether or not the enhancer repeats alone stimulate or repress expression from the downstream gene promoter. Stimulation of gene promoter transcription by the spacer promoter requires the rDNA enhancer sequences to be present between the spacer promoter and gene promoter and to be oriented as in native rDNA. Stimulation also requires that the spacer promoter be oriented toward the enhancer and gene promoter. However, stimulation does not correlate with transcription from the spacer promoter because the level of stimulation is not altered by either insertion of a functional mouse RNA polymerase I transcriptional terminator between the spacer promoter and enhancer or replacement with a much more active heterologous polymerase I promoter. Further analysis with a series of mutated spacer promoters indicates that the stimulatory activity does not reside in the major promoter domains but requires the central region of the promoter that has been correlated with enhancer responsiveness in vivo.

scholarly journals Nucleolin Is Required for RNA Polymerase I Transcription In Vivo

2006 ◽  
Vol 27 (3) ◽  
pp. 937-948 ◽  
Author(s):  
Brenden Rickards ◽  
S. J. Flint ◽  
Michael D. Cole ◽  
Gary LeRoy
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Rna Polymerase I ◽  
Rrna Genes ◽  
Accessory Proteins ◽  
Naked Dna ◽  
Nucleolar Chromatin ◽  
Polymerase I

ABSTRACT Eukaryotic genomes are packaged with histones and accessory proteins in the form of chromatin. RNA polymerases and their accessory proteins are sufficient for transcription of naked DNA, but not of chromatin, templates in vitro. In this study, we purified and identified nucleolin as a protein that allows RNA polymerase II to transcribe nucleosomal templates in vitro. As immunofluorescence confirmed that nucleolin localizes primarily to nucleoli with RNA polymerase I, we demonstrated that nucleolin allows RNA polymerase I transcription of chromatin templates in vitro. The results of chromatin immunoprecipitation experiments established that nucleolin is associated with chromatin containing rRNA genes transcribed by RNA polymerase I but not with genes transcribed by RNA polymerase II or III. Knockdown of nucleolin by RNA interference resulted in specific inhibition of RNA polymerase I transcription. We therefore propose that an important function of nucleolin is to permit RNA polymerase I to transcribe nucleolar chromatin.

Transcription of the mouse ribosomal spacer region

1984 ◽  
Vol 4 (5) ◽  
pp. 822-828
Author(s):  
K M Wood ◽  
L H Bowman ◽  
E A Thompson
Keyword(s):  
Rna Polymerase ◽  
Dna Sequences ◽  
Blot Hybridization ◽  
Rna Polymerase I ◽  
Dot Blot ◽  
Intact Cells ◽  
Nuclease Mapping ◽  
Polymerase I

This paper describes experiments designed to test the hypothesis that DNA sequences upstream from the mouse rRNA promoter are transcribed in vivo or in vitro. Plasmid pB28 contains a SalI restriction fragment that extends from -169 to -1,894 base pairs, with respect to the origin of transcription of pre-rRNA. Labeled RNA synthesized in intact cells does not hybridize to this region. Neither S1 nuclease mapping nor RNA dot blot hybridization revealed the presence of sequences complementary to this region. Transcriptional studies carried out in vitro indicated that this region is not transcribed under conditions that are optimal for utilization of the authentic rRNA promoter. Moreover, this region does not appear to form stable transcription complexes with RNA polymerase I transcription components. These data indicate that the mouse rDNA repeating unit differs from those of Xenopus spp. and Drosophila melanogaster in that reduplicated RNA polymerase I promoters are not found in the mouse rDNA spacer region.

scholarly journals The dynamic assembly of distinct RNA polymerase I complexes modulates rDNA transcription

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Eva Torreira ◽  
Jaime Alegrio Louro ◽  
Irene Pazos ◽  
Noelia González-Polo ◽  
David Gil-Carton ◽  
...  
Keyword(s):  
Cell Growth ◽  
Rna Polymerase ◽  
Ribosome Biogenesis ◽  
Mutational Analysis ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rdna Transcription ◽  
Pol I ◽  
Polymerase I

Cell growth requires synthesis of ribosomal RNA by RNA polymerase I (Pol I). Binding of initiation factor Rrn3 activates Pol I, fostering recruitment to ribosomal DNA promoters. This fundamental process must be precisely regulated to satisfy cell needs at any time. We present in vivo evidence that, when growth is arrested by nutrient deprivation, cells induce rapid clearance of Pol I–Rrn3 complexes, followed by the assembly of inactive Pol I homodimers. This dual repressive mechanism reverts upon nutrient addition, thus restoring cell growth. Moreover, Pol I dimers also form after inhibition of either ribosome biogenesis or protein synthesis. Our mutational analysis, based on the electron cryomicroscopy structures of monomeric Pol I alone and in complex with Rrn3, underscores the central role of subunits A43 and A14 in the regulation of differential Pol I complexes assembly and subsequent promoter association.

scholarly journals Casein Kinase 2 Associates with Initiation-Competent RNA Polymerase I and Has Multiple Roles in Ribosomal DNA Transcription

2006 ◽  
Vol 26 (16) ◽  
pp. 5957-5968 ◽  
Author(s):  
Tatiana B. Panova ◽  
Kostya I. Panov ◽  
Jackie Russell ◽  
Joost C. B. M. Zomerdijk
Keyword(s):  
Rna Polymerase ◽  
Ribosomal Dna ◽  
Casein Kinase ◽  
Casein Kinase 2 ◽  
Rna Polymerase I ◽  
Positive Effects ◽  
Pol I ◽  
Polymerase I

ABSTRACT Mammalian RNA polymerase I (Pol I) complexes contain a number of associated factors, some with undefined regulatory roles in transcription. We demonstrate that casein kinase 2 (CK2) in human cells is associated specifically only with the initiation-competent Pol Iβ isoform and not with Pol Iα. Chromatin immunoprecipitation analysis places CK2 at the ribosomal DNA (rDNA) promoter in vivo. Pol Iβ-associated CK2 can phosphorylate topoisomerase IIα in Pol Iβ, activator upstream binding factor (UBF), and selectivity factor 1 (SL1) subunit TAFI110. A potent and selective CK2 inhibitor, 3,8-dibromo-7-hydroxy-4-methylchromen-2-one, limits in vitro transcription to a single round, suggesting a role for CK2 in reinitiation. Phosphorylation of UBF by CK2 increases SL1-dependent stabilization of UBF at the rDNA promoter, providing a molecular mechanism for the stimulatory effect of CK2 on UBF activation of transcription. These positive effects of CK2 in Pol I transcription contrast to that wrought by CK2 phosphorylation of TAFI110, which prevents SL1 binding to rDNA, thereby abrogating the ability of SL1 to nucleate preinitiation complex (PIC) formation. Thus, CK2 has the potential to regulate Pol I transcription at multiple levels, in PIC formation, activation, and reinitiation of transcription.

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