scholarly journals Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes

Open Biology ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 170001 ◽  
Author(s):  
Ewa Leśniewska ◽  
Magdalena Boguta
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Rna Polymerase Iii ◽  
Negative Regulator ◽  
Promoter Regions ◽  
Polymerase Iii ◽  
Short Transcript ◽  
Nucleotide Resolution ◽  
Pol Iii

RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency.

scholarly journals Structural basis of RNA polymerase III transcription repression by Maf1

2019 ◽  
Author(s):  
Matthias K. Vorländer ◽  
Florence Baudin ◽  
Robyn D. Moir ◽  
René Wetzel ◽  
Wim J. H. Hagen ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Binding Site ◽  
Transcription Initiation ◽  
Rna Polymerase Iii ◽  
Structural Basis ◽  
Metabolic Efficiency ◽  
Transcription Repression ◽  
Polymerase Iii ◽  
Wide Range ◽  
Pol Iii

ABSTRACTMaf1 is a highly conserved central regulator of transcription by RNA polymerase III (Pol III), and Maf1 activity influences a wide range of phenotypes from metabolic efficiency to lifespan. Here, we present a 3.3 Å cryo-EM structure of yeast Maf1 bound to Pol III, which establishes how Maf1 achieves transcription repression. In the Maf1-bound state, Pol III elements that are involved in transcription initiation are sequestered, and the active site is sealed off due to ordering of the mobile C34 winged helix 2 domain. Specifically, the Maf1 binding site overlaps with the binding site of the Pol III transcription factor TFIIIB and DNA in the pre-initiation complex, rationalizing that binding of Maf1 and TFIIIB to Pol III are mutually exclusive. We validate our structure using variants of Maf1 with impaired transcription-inhibition activity. These results reveal the exact mechanism of Pol III inhibition by Maf1, and rationalize previous biochemical data.

Transcription factor TFIIIB and transcription by RNA polymerase III

2006 ◽  
Vol 34 (6) ◽  
pp. 1082-1087 ◽  
Author(s):  
G.A. Kassavetis ◽  
E.P. Geiduschek
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Transcriptional Start Site ◽  
Rna Polymerase Iii ◽  
Initiation Factor ◽  
Regulation Of Transcription ◽  
Start Site ◽  
High Mobility Group Protein ◽  
Polymerase Iii ◽  
Pol Iii

pol (RNA polymerase) III is charged with the task of transcribing nuclear genes encoding diverse small structural and catalytic RNAs. We present a brief review of the current understanding of several aspects of the pol III transcription apparatus. The focus is on yeast and, more specifically, on Saccharomyces cerevisiae; preponderant attention is given to the TFs (transcription initiation factors) and especially to TFIIIB, which is the core pol III initiation factor by virtue of its role in recruiting pol III to the transcriptional start site and its essential roles in forming the transcription-ready open promoter complex. Certain relatively recent developments are also selected for brief comment: (i) the genome-wide analysis of occupancy of pol III-transcribed genes (and other loci) by the transcription apparatus and the location of pol III transcription in the cell; (ii) progress toward a mechanistic and molecular understanding of the regulation of transcription by pol III in yeast; and (iii) recent experiments identifying a high mobility group protein as a fidelity factor that assures selection of the precise transcriptional start site at certain pol III promoters.

scholarly journals A Region of Bdp1 Necessary for Transcription Initiation That Is Located within the RNA Polymerase III Active Site Cleft

2015 ◽  
Vol 35 (16) ◽  
pp. 2831-2840 ◽  
Author(s):  
Hui-Lan Hu ◽  
Chih-Chien Wu ◽  
Jin-Cheng Lee ◽  
Hung-Ta Chen
Keyword(s):  
Transcription Factor ◽  
Rna Polymerase ◽  
Active Site ◽  
Transcription Initiation ◽  
Rna Polymerase Iii ◽  
Terminal Region ◽  
Preinitiation Complex ◽  
Polymerase Iii ◽  
Active Site Cleft ◽  
Pol Iii

The RNA polymerase III (Pol III)-specific transcription factor Bdp1 is crucial to Pol III recruitment and promoter opening in transcription initiation, yet structural information is sparse. To examine its protein-binding targets within the preinitiation complex at the residue level, photoreactive amino acids were introduced intoSaccharomyces cerevisiaeBdp1. Mutations within the highly conserved SANT domain cross-linked to the transcription factor IIB (TFIIB)-related transcription factor Brf1, consistent with the findings of previous studies. In addition, we identified an essential N-terminal region that cross-linked with the Pol III catalytic subunit C128 as well as Brf1. Closer examination revealed that this region interacted with the C128 N-terminal region, the N-terminal half of Brf1, and the C-terminal domain of the C37 subunit, together positioning this region within the active site cleft of the preinitiation complex. With our functional data, our analyses identified an essential region of Bdp1 that is positioned within the active site cleft of Pol III and necessary for transcription initiation.

scholarly journals The transcription reinitiation properties of RNA polymerase III in the absence of transcription factors

2008 ◽  
Vol 13 (1) ◽  
Author(s):  
Roberto Ferrari ◽  
Giorgio Dieci
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Rna Polymerase Iii ◽  
In Vitro Transcription ◽  
Transcription Unit ◽  
Transcription System ◽  
Transcription Reinitiation ◽  
Pol Iii

AbstractTranscription reinitiation by RNA polymerase (Pol) III proceeds through facilitated recycling, a process by which the terminating Pol III, assisted by the transcription factors TFIIIB and TFIIIC, rapidly reloads onto the same transcription unit. To get further insight into the Pol III transcription mechanism, we analyzed the kinetics of transcription initiation and reinitiation of a simplified in vitro transcription system consisting only of Pol III and template DNA. The data indicates that, in the absence of transcription factors, first-round transcription initiation by Pol III proceeds at a normal rate, while facilitated reinitiation during subsequent cycles is compromised.

scholarly journals Insights into Transcription Initiation and Termination from the Electron Microscopy Structure of Yeast RNA Polymerase III

2007 ◽  
Vol 25 (6) ◽  
pp. 813-823 ◽  
Author(s):  
Carlos Fernández-Tornero ◽  
Bettina Böttcher ◽  
Michel Riva ◽  
Christophe Carles ◽  
Ulrich Steuerwald ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Transcription Initiation ◽  
Rna Polymerase Iii ◽  
Polymerase Iii

scholarly journals Involvement of RNA Polymerase III in Immune Responses

2015 ◽  
Vol 35 (10) ◽  
pp. 1848-1859 ◽  
Author(s):  
Damian Graczyk ◽  
Robert J. White ◽  
Kevin M. Ryan
Keyword(s):  
Transcription Factor ◽  
Immune Responses ◽  
Rna Polymerase ◽  
Rna Polymerase Iii ◽  
Trna Genes ◽  
Malignant Cells ◽  
Polymerase Iii ◽  
Mouse Macrophages ◽  
Tightly Coupled ◽  
Pol Iii

Inflammation in the tumor microenvironment has many tumor-promoting effects. In particular, tumor-associated macrophages (TAMs) produce many cytokines which can support tumor growth by promoting survival of malignant cells, angiogenesis, and metastasis. Enhanced cytokine production by TAMs is tightly coupled with protein synthesis. In turn, translation of proteins depends on tRNAs, short abundant transcripts that are made by RNA polymerase III (Pol III). Here, we connect these facts by showing that stimulation of mouse macrophages with lipopolysaccharides (LPS) from the bacterial cell wall causes transcriptional upregulation of tRNA genes. The transcription factor NF-κB is a key transcription factor mediating inflammatory signals, and we report that LPS treatment causes an increased association of the NF-κB subunit p65 with tRNA genes. In addition, we show that p65 can directly associate with the Pol III transcription factor TFIIIB and that overexpression of p65 induces Pol III-dependent transcription. As a consequence of these effects, we show that inhibition of Pol III activity in macrophages restrains cytokine secretion and suppresses phagocytosis, two key functional characteristics of these cells. These findings therefore identify a radical new function for Pol III in the regulation of macrophage function which may be important for the immune responses associated with both normal and malignant cells.

Eukaryotic transcription termination factor La mediates transcript release and facilitates reinitiation by RNA polymerase III

1994 ◽  
Vol 14 (3) ◽  
pp. 2147-2158
Author(s):  
R J Maraia ◽  
D J Kenan ◽  
J D Keene
Keyword(s):  
Rna Polymerase ◽  
Rna Binding ◽  
Transcription Termination ◽  
Rna Polymerase Iii ◽  
Class Iii ◽  
Ample Evidence ◽  
Polymerase Iii ◽  
Transcription Complexes ◽  
Pol Iii

Ample evidence indicates that Alu family interspersed elements retrotranspose via primary transcripts synthesized by RNA polymerase III (pol III) and that this transposition sometimes results in genetic disorders in humans. However, Alu primary transcripts can be processed posttranscriptionally, diverting them away from the transposition pathway. The pol III termination signal of a well-characterized murine B1 (Alu-equivalent) element inhibits RNA 3' processing, thereby stabilizing the putative transposition intermediary. We used an immobilized template-based assay to examine transcription termination by VA1, 7SL, and Alu class III templates and the role of transcript release in the pol III terminator-dependent inhibition of processing of B1-Alu transcripts. We found that the RNA-binding protein La confers this terminator-dependent 3' processing inhibition on transcripts released from the B1-Alu template. Using pure recombinant La protein and affinity-purified transcription complexes, we also demonstrate that La facilitates multiple rounds of transcription reinitiation by pol III. These results illustrate an important role for La in RNA production by demonstrating its ability to clear the termination sites of class III templates, thereby promoting efficient use of transcription complexes by pol III. The role of La as a potential regulatory factor in transcript maturation and how this might apply to Alu interspersed elements is discussed.

scholarly journals Inhibition of TATA Binding Protein Dimerization by RNA Polymerase III Transcription Initiation Factor Brf1

2004 ◽  
Vol 279 (31) ◽  
pp. 32401-32406 ◽  
Author(s):  
Diane E. Alexander ◽  
David J. Kaczorowski ◽  
Amy J. Jackson-Fisher ◽  
Drew M. Lowery ◽  
Sara J. Zanton ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Binding Protein ◽  
Rna Polymerase Iii ◽  
Tata Binding Protein ◽  
Initiation Factor ◽  
Protein Dimerization ◽  
Polymerase Iii ◽  
Transcription Initiation Factor
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