The RNA polymerase I-specific transcription initiation factor UBF is associated with transcriptionally active and inactive ribosomal genes

Chromosoma ◽  
1993 ◽  
Vol 102 (9) ◽  
pp. 599-611 ◽  
Author(s):  
Olga V. Zatsepina ◽  
Renate Voit ◽  
Ingrid Grummt ◽  
Herbert Spring ◽  
Michael V. Semenov ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Ribosomal Genes ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Transcription Initiation Factor ◽  
Polymerase I

scholarly journals Two RNA Polymerase I Subunits Control the Binding and Release of Rrn3 during Transcription

2007 ◽  
Vol 28 (5) ◽  
pp. 1596-1605 ◽  
Author(s):  
Frédéric Beckouet ◽  
Sylvie Labarre-Mariotte ◽  
Benjamin Albert ◽  
Yukiko Imazawa ◽  
Michel Werner ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Binding Domain ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
C Terminus ◽  
Transcription Initiation Factor ◽  
Polymerase I ◽  
Polymerase Mutants

ABSTRACT Rpa34 and Rpa49 are nonessential subunits of RNA polymerase I, conserved in species from Saccharomyces cerevisiae and Schizosaccharomyces pombe to humans. Rpa34 bound an N-terminal region of Rpa49 in a two-hybrid assay and was lost from RNA polymerase in an rpa49 mutant lacking this Rpa34-binding domain, whereas rpa34Δ weakened the binding of Rpa49 to RNA polymerase. rpa34Δ mutants were caffeine sensitive, and the rpa34Δ mutation was lethal in a top1Δ mutant and in rpa14Δ, rpa135(L656P), and rpa135(D395N) RNA polymerase mutants. These defects were shared by rpa49Δ mutants, were suppressed by the overexpression of Rpa49, and thus, were presumably mediated by Rpa49 itself. rpa49 mutants lacking the Rpa34-binding domain behaved essentially like rpa34Δ mutants, but strains carrying rpa49Δ and rpa49-338::HIS3 (encoding a form of Rpa49 lacking the conserved C terminus) had reduced polymerase occupancy at 30°C, failed to grow at 25°C, and were sensitive to 6-azauracil and mycophenolate. Mycophenolate almost fully dissociated the mutant polymerase from its ribosomal DNA (rDNA) template. The rpa49Δ and rpa49-338::HIS3 mutations had a dual effect on the transcription initiation factor Rrn3 (TIF-IA). They partially impaired its recruitment to the rDNA promoter, an effect that was bypassed by an N-terminal deletion of the Rpa43 subunit encoded by rpa43-35,326, and they strongly reduced the release of the Rrn3 initiation factor during elongation. These data suggest a dual role of the Rpa49-Rpa34 dimer during the recruitment of Rrn3 and its subsequent dissociation from the elongating polymerase.

scholarly journals A Novel RNA Polymerase I Transcription Initiation Factor, TIF-IE, Commits rRNA Genes by Interaction with TIF-IB, Not by DNA Binding

2002 ◽  
Vol 22 (3) ◽  
pp. 750-761 ◽  
Author(s):  
Anna Maria Al-Khouri ◽  
Marvin R. Paule
Keyword(s):  
Dna Binding ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rrna Genes ◽  
Rrna Transcription ◽  
Transcription Initiation Factor ◽  
Binding Factor ◽  
Polymerase I

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.

Events during eucaryotic rRNA transcription initiation and elongation: conversion from the closed to the open promoter complex requires nucleotide substrates

1988 ◽  
Vol 8 (5) ◽  
pp. 1940-1946
Author(s):  
E Bateman ◽  
M R Paule
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Topological Analysis ◽  
Acanthamoeba Castellanii ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rrna Transcription ◽  
Promoter Complex ◽  
Polymerase I

Chemical footprinting and topological analysis were carried out on the Acanthamoeba castellanii rRNA transcription initiation factor (TIF) and RNA polymerase I complexes with DNA during transcription initiation and elongation. The results show that the binding of TIF and polymerase to the promoter does not alter the supercoiling of the DNA template and the template does not become sensitive to modification by diethylpyrocarbonate, which can identify melted DNA regions. Thus, in contrast to bacterial RNA polymerase, the eucaryotic RNA polymerase I-promoter complex is in a closed configuration preceding addition of nucleotides in vitro. Initiation and 3'-O-methyl CTP-limited translocation by RNA polymerase I results in separation of the polymerase-TIF footprints, leaving the TIF footprint unaltered. In contrast, initiation and translocation result in a significant change in the conformation of the polymerase-DNA complex, culminating in an unwound DNA region of at least 10 base pairs.

scholarly journals Phosphorylation by Casein Kinase 2 Facilitates rRNA Gene Transcription by Promoting Dissociation of TIF-IA from Elongating RNA Polymerase I

2008 ◽  
Vol 28 (16) ◽  
pp. 4988-4998 ◽  
Author(s):  
Holger Bierhoff ◽  
Miroslav Dundr ◽  
Annemieke A. Michels ◽  
Ingrid Grummt
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Casein Kinase ◽  
Casein Kinase 2 ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rrna Gene ◽  
Rdna Transcription ◽  
Pol I ◽  
Polymerase I

ABSTRACT The protein kinase casein kinase 2 (CK2) phosphorylates different components of the RNA polymerase I (Pol I) transcription machinery and exerts a positive effect on rRNA gene (rDNA) transcription. Here we show that CK2 phosphorylates the transcription initiation factor TIF-IA at serines 170 and 172 (Ser170/172), and this phosphorylation triggers the release of TIF-IA from Pol I after transcription initiation. Inhibition of Ser170/172 phosphorylation or covalent tethering of TIF-IA to the RPA43 subunit of Pol I inhibits rDNA transcription, leading to perturbation of nucleolar structure and cell cycle arrest. Fluorescence recovery after photobleaching and chromatin immunoprecipitation experiments demonstrate that dissociation of TIF-IA from Pol I is a prerequisite for proper transcription elongation. In support of phosphorylation of TIF-IA switching from the initiation into the elongation phase, dephosphorylation of Ser170/172 by FCP1 facilitates the reassociation of TIF-IA with Pol I, allowing a new round of rDNA transcription. The results reveal a mechanism by which the functional interplay between CK2 and FCP1 sustains multiple rounds of Pol I transcription.

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