Transcription termination by RNA polymerase III: uncoupling of polymerase release from termination signal recognition

1992 ◽  
Vol 12 (5) ◽  
pp. 2260-2272
Author(s):  
F E Campbell ◽  
D R Setzer
Keyword(s):  
Rna Polymerase ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Signal Recognition ◽  
Polymerase Iii ◽  
5S Rrna Gene ◽  
Nascent Rna

Xenopus RNA polymerase III specifically initiates transcription on poly(dC)-tailed DNA templates in the absence of other class III transcription factors normally required for transcription initiation. In experimental analyses of transcription termination using DNA fragments with a 5S rRNA gene positioned downstream of the tailed end, only 40% of the transcribing polymerase molecules terminate at the normally efficient Xenopus borealis somatic-type 5S rRNA terminators; the remaining 60% read through these signals and give rise to runoff transcripts. We find that the nascent RNA strand is inefficiently displaced from the DNA template during transcription elongation. Interestingly, only polymerases synthesizing a displaced RNA terminate at the 5S rRNA gene terminators; when the nascent RNA is not displaced from the template, read-through transcripts are synthesized. RNAs with 3' ends at the 5S rRNA gene terminators are judged to result from authentic termination events on the basis of multiple criteria, including kinetic properties, the precise 3' ends generated, release of transcripts from the template, and recycling of the polymerase. Even though only 40% of the polymerase molecules ultimately terminate at either of the tandem 5S rRNA gene terminators, virtually all polymerases pause there, demonstrating that termination signal recognition can be experimentally uncoupled from polymerase release. Thus, termination is dependent on RNA strand displacement during transcription elongation, whereas termination signal recognition is not. We interpret our results in terms of a two-step model for transcription termination in which polymerase release is dependent on the fate of the nascent RNA strand during transcription elongation.

scholarly journals Transcription termination by RNA polymerase III: uncoupling of polymerase release from termination signal recognition.

1992 ◽  
Vol 12 (5) ◽  
pp. 2260-2272 ◽  
Author(s):  
F E Campbell ◽  
D R Setzer
Keyword(s):  
Rna Polymerase ◽  
Transcription Termination ◽  
Transcription Elongation ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Signal Recognition ◽  
Polymerase Iii ◽  
5S Rrna Gene ◽  
Nascent Rna

Xenopus RNA polymerase III specifically initiates transcription on poly(dC)-tailed DNA templates in the absence of other class III transcription factors normally required for transcription initiation. In experimental analyses of transcription termination using DNA fragments with a 5S rRNA gene positioned downstream of the tailed end, only 40% of the transcribing polymerase molecules terminate at the normally efficient Xenopus borealis somatic-type 5S rRNA terminators; the remaining 60% read through these signals and give rise to runoff transcripts. We find that the nascent RNA strand is inefficiently displaced from the DNA template during transcription elongation. Interestingly, only polymerases synthesizing a displaced RNA terminate at the 5S rRNA gene terminators; when the nascent RNA is not displaced from the template, read-through transcripts are synthesized. RNAs with 3' ends at the 5S rRNA gene terminators are judged to result from authentic termination events on the basis of multiple criteria, including kinetic properties, the precise 3' ends generated, release of transcripts from the template, and recycling of the polymerase. Even though only 40% of the polymerase molecules ultimately terminate at either of the tandem 5S rRNA gene terminators, virtually all polymerases pause there, demonstrating that termination signal recognition can be experimentally uncoupled from polymerase release. Thus, termination is dependent on RNA strand displacement during transcription elongation, whereas termination signal recognition is not. We interpret our results in terms of a two-step model for transcription termination in which polymerase release is dependent on the fate of the nascent RNA strand during transcription elongation.

DNA methylation inhibits transcription by RNA polymerase III of a tRNA gene, but not of a 5S rRNA gene

FEBS Letters ◽  
1990 ◽  
Vol 269 (2) ◽  
pp. 358-362 ◽  
Author(s):  
Daniel Besser ◽  
Frank Götz ◽  
Kai Schulze-Forster ◽  
Herbert Wagner ◽  
Hans Kröger ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Rna Polymerase ◽  
Trna Gene ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Polymerase Iii ◽  
5S Rrna Gene

scholarly journals Displacement of Xenopus transcription factor IIIA from a 5S rRNA gene by a transcribing RNA polymerase.

1991 ◽  
Vol 11 (8) ◽  
pp. 3978-3986 ◽  
Author(s):  
F E Campbell ◽  
D R Setzer
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Rna Polymerase ◽  
Internal Control ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Transcription Factor Iiia ◽  
Polymerase Iii ◽  
5S Rrna Gene

In the absence of other components of the RNA polymerase III transcription machinery, transcription factor IIIA (TFIIIA) can be displaced from both strands of its DNA-binding site (the internal control region) on the somatic-type 5S rRNA gene of Xenopus borealis during transcription elongation by bacteriophage T7 RNA polymerase, regardless of which DNA strand is transcribed. Furthermore, substantial displacement is observed after the template has been transcribed only once. Since the complete 5S rRNA transcription complex has previously been shown to remain stably bound to the gene during repeated rounds of transcription by either RNA polymerase III or bacteriophage SP6 RNA polymerase, these results indicate that a factor(s) in addition to TFIIIA is required to create a complex that will remain stably associated with the template during transcription. Thus, transcription complex stability during passage of RNA polymerase cannot be explained solely on the basis of the DNA-binding properties of TFIIIA.

Transcription factor requirements for in vitro formation of transcriptionally competent 5S rRNA gene chromatin

1990 ◽  
Vol 10 (5) ◽  
pp. 2390-2401
Author(s):  
S J Felts ◽  
P A Weil ◽  
R Chalkley
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Active Chromatin ◽  
Polymerase Iii ◽  
Protein Dna Interactions ◽  
5S Rrna Gene

The Saccharomyces cerevisiae 5S rRNA gene was used as a model system to study the requirements for assembling transcriptionally active chromatin in vitro with purified components. When a plasmid containing yeast 5S rDNA was assembled into chromatin with purified core histones, the gene was inaccessible to the yeast class III gene transcription machinery. Preformation of a 5S rRNA gene-TFIIIA complex was not sufficient for the formation of active chromatin in this in vitro system. Instead, a complete transcription factor complex consisting of TFIIIA, TFIIIB, and TFIIIC needed to be formed before the addition of histones in order for the 5S chromatin to subsequently be transcribed by RNA polymerase III. Various 5S rRNA maxigenes were constructed and used for chromatin assembly studies. In vitro transcription from these assembled 5S maxigenes revealed that RNA polymerase III was readily able to transcribe through one, two, or four nucleosomes. However, we found that RNA polymerase III was not able to efficiently transcribe a chromatin template containing a more extended array of nucleosomes. In vivo expression experiments indicated that all in vitro-constructed maxigenes were transcriptionally competent. Analyses of protein-DNA interactions formed on these maxigenes in vivo by indirect end labeling indicated that there are extensive interactions throughout the length of these maxigenes. The patterns of protein-DNA interactions formed on these genes are consistent with these DNAs being assembled into extensive nucleosomal arrays.

scholarly journals Transcription factor requirements for in vitro formation of transcriptionally competent 5S rRNA gene chromatin.

1990 ◽  
Vol 10 (5) ◽  
pp. 2390-2401 ◽  
Author(s):  
S J Felts ◽  
P A Weil ◽  
R Chalkley
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Active Chromatin ◽  
Polymerase Iii ◽  
Protein Dna Interactions ◽  
5S Rrna Gene

The Saccharomyces cerevisiae 5S rRNA gene was used as a model system to study the requirements for assembling transcriptionally active chromatin in vitro with purified components. When a plasmid containing yeast 5S rDNA was assembled into chromatin with purified core histones, the gene was inaccessible to the yeast class III gene transcription machinery. Preformation of a 5S rRNA gene-TFIIIA complex was not sufficient for the formation of active chromatin in this in vitro system. Instead, a complete transcription factor complex consisting of TFIIIA, TFIIIB, and TFIIIC needed to be formed before the addition of histones in order for the 5S chromatin to subsequently be transcribed by RNA polymerase III. Various 5S rRNA maxigenes were constructed and used for chromatin assembly studies. In vitro transcription from these assembled 5S maxigenes revealed that RNA polymerase III was readily able to transcribe through one, two, or four nucleosomes. However, we found that RNA polymerase III was not able to efficiently transcribe a chromatin template containing a more extended array of nucleosomes. In vivo expression experiments indicated that all in vitro-constructed maxigenes were transcriptionally competent. Analyses of protein-DNA interactions formed on these maxigenes in vivo by indirect end labeling indicated that there are extensive interactions throughout the length of these maxigenes. The patterns of protein-DNA interactions formed on these genes are consistent with these DNAs being assembled into extensive nucleosomal arrays.

Displacement of Xenopus transcription factor IIIA from a 5S rRNA gene by a transcribing RNA polymerase

1991 ◽  
Vol 11 (8) ◽  
pp. 3978-3986
Author(s):  
F E Campbell ◽  
D R Setzer
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Rna Polymerase ◽  
Internal Control ◽  
Rna Polymerase Iii ◽  
5S Rrna ◽  
Rrna Gene ◽  
Transcription Factor Iiia ◽  
Polymerase Iii ◽  
5S Rrna Gene

In the absence of other components of the RNA polymerase III transcription machinery, transcription factor IIIA (TFIIIA) can be displaced from both strands of its DNA-binding site (the internal control region) on the somatic-type 5S rRNA gene of Xenopus borealis during transcription elongation by bacteriophage T7 RNA polymerase, regardless of which DNA strand is transcribed. Furthermore, substantial displacement is observed after the template has been transcribed only once. Since the complete 5S rRNA transcription complex has previously been shown to remain stably bound to the gene during repeated rounds of transcription by either RNA polymerase III or bacteriophage SP6 RNA polymerase, these results indicate that a factor(s) in addition to TFIIIA is required to create a complex that will remain stably associated with the template during transcription. Thus, transcription complex stability during passage of RNA polymerase cannot be explained solely on the basis of the DNA-binding properties of TFIIIA.

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.

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