Faculty Opinions recommendation of A subcomplex of RNA polymerase III subunits involved in transcription termination and reinitiation.

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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RNA polymerase III subunits C37/53 modulate rU:dA hybrid 3′ end dynamics during transcription termination

Nucleic Acids Research ◽

10.1093/nar/gky1109 ◽

2018 ◽

Vol 47 (1) ◽

pp. 310-327 ◽

Cited By ~ 5

Author(s):

Saurabh Mishra ◽

Richard J Maraia

Keyword(s):

Rna Polymerase ◽

Transcription Termination ◽

Rna Polymerase Iii ◽

Polymerase Iii

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Mechanism of Transcription Termination by RNA Polymerase III Utilizes a Non-template Strand Sequence-Specific Signal Element

Molecular Cell ◽

10.1016/j.molcel.2015.04.002 ◽

2015 ◽

Vol 58 (6) ◽

pp. 1124-1132 ◽

Cited By ~ 41

Author(s):

Aneeshkumar G. Arimbasseri ◽

Richard J. Maraia

Keyword(s):

Rna Polymerase ◽

Transcription Termination ◽

Rna Polymerase Iii ◽

Template Strand ◽

Specific Signal ◽

Signal Element ◽

Polymerase Iii

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Termination-altering mutations in the second-largest subunit of yeast RNA polymerase III.

Molecular and Cellular Biology ◽

10.1128/mcb.15.3.1467 ◽

1995 ◽

Vol 15 (3) ◽

pp. 1467-1478 ◽

Cited By ~ 27

Author(s):

S A Shaaban ◽

B M Krupp ◽

B D Hall

Keyword(s):

Amino Acid ◽

Rna Polymerase ◽

Transcription Initiation ◽

Transcription Termination ◽

Rna Polymerase Iii ◽

In Vitro Transcription ◽

The Other ◽

Polymerase Iii

In order to identify catalytically important amino acid changes within the second-largest subunit of yeast RNA polymerase III, we mutagenized selected regions of its gene (RET1) and devised in vivo assays for both increased and decreased transcription termination by this enzyme. Using as the reporter gene a mutant SUP4-o tRNA gene that in one case terminates prematurely and in the other case fails to terminate, we screened mutagenized RET1 libraries for reduced and increased transcription termination, respectively. The gain in suppression phenotype was in both cases scored as a reduction in the accumulation of red pigment in yeast strains harboring the ade2-1 ochre mutation. Termination-altering mutations were obtained in regions of the RET1 gene encoding amino acids 300 to 325, 455 to 486, 487 to 521, and 1061 to 1082 of the protein. In degree of amino acid sequence conservation, these range from highly variable in the first to highly conserved in the last two regions. Residues 300 to 325 yielded mainly reduced-termination mutants, while in region 1061 to 1082, increased-termination mutants were obtained exclusively. All mutants recovered, while causing gain of suppression with one SUP4 allele, brought about a reduction in suppression with the other allele, thus confirming that the phenotype is due to altered termination rather than an elevated level of transcription initiation. In vitro transcription reactions performed with extracts from several strong mutants demonstrated that the mutant polymerases respond to RNA terminator sequences in a manner that matches their in vivo termination phenotypes.

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

Molecular and Cellular Biology ◽

10.1128/mcb.14.3.2147 ◽

1994 ◽

Vol 14 (3) ◽

pp. 2147-2158 ◽

Cited By ~ 97

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

Molecular and Cellular Biology ◽

10.1128/mcb.12.5.2260-2272.1992 ◽

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.

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