Budding yeast RNA polymerases I and II employ parallel mechanisms of transcriptional termination (original) (raw)

Disengaging polymerase: Terminating RNA polymerase II transcription in budding yeast

Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013

Termination of transcription by RNA polymerase II requires two distinct processes: The formation of a defined 3′ end of the transcribed RNA, as well as the disengagement of RNA polymerase from its DNA template. Both processes are intimately connected and equally pivotal in the process of functional messenger RNA production. However, research in recent years has elaborated how both processes can additionally be employed to control gene expression in qualitative and quantitative ways. This review embraces these new findings and attempts to paint a broader picture of how this final step in the transcription cycle is of critical importance to many aspects of gene regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.

The Reb1-homologue Ydr026c/Nsi1 is required for efficient RNA polymerase I termination in yeast

The EMBO Journal, 2012

Several DNA cis-elements and transacting factors were described to be involved in transcription termination and to release the elongating RNA polymerases from their templates. Different models for the molecular mechanism of transcription termination have been suggested for eukaryotic RNA polymerase I (Pol I) from results of in vitro and in vivo experiments. To analyse the molecular requirements for yeast RNA Pol I termination, an in vivo approach was used in which efficient termination resulted in growth inhibition. This led to the identification of a Myb-like protein, Ydr026c, as bona fide termination factor, now designated Nsi1 (NTS1 silencing protein 1), since it was very recently described as silencing factor of ribosomal DNA. Possible Nsi1 functions in regard to the mechanism of transcription termination are discussed.

Efficient termination of transcription by RNA polymerase I requires the 5' exonuclease Rat1 in yeast

Genes & Development, 2008

During transcription termination by RNA polymerase II on protein-coding genes, the nuclear 5 exonuclease Rat1/Xrn2 degrades the nascent transcript downstream from the polyadenylation site and "torpedoes" the polymerase. We report that the activity of Rat1 is also required for efficient termination by RNA polymerase I (Pol I) on the rDNA. In strains lacking catalytically active Rat1 or its cofactor Rai1, Pol I reads through the major, "Reb1-dependent" terminator (T1) but stops downstream at the "fail-safe" terminator (T2) and replication fork barrier (RFB). The absence of both Rat1 and the RFB-binding protein Fob1 increased Pol I read-through of T2 and the RFB. We propose that cotranscriptional cleavage of the pre-rRNA by the endonuclease Rnt1 generates a loading site for the Rat1/Rai1 complex, which then degrades the nascent transcript. When Rat1 catches Pol I, which is predicted to be paused at T1, transcription is terminated.

Transcriptional termination by RNA polymerase I requires the small subunit Rpa12p

Proceedings of the National Academy of Sciences, 2004

We identify Rpa12p of RNA polymerase I (Pol I) as a termination factor. Combined analyses using transcription run-on, electron microscopy-visualized chromatin spreading and RT-PCR have been applied to the rRNA-encoding genes of Saccharomyces cerevisiae . These confirm that Pol I termination occurs close to the Reb1p-dependent terminator in wild-type strains. However, deletion mutants for the 3′ end-processing enzyme Rnt1p or the Rpa12p subunit of Pol I both show Pol I transcription in the spacer. For Δ rpa12 , these spacer polymerases are devoid of nascent transcripts, suggesting they are immediately degraded. The homology of Rpa12p to the small subunit Rpb9p of Pol II and Rpc11p of Pol III, both implicated in transcriptional termination, points to a common termination mechanism for all three classes of RNA polymerase.

Transcriptional termination signals for RNA polymerase II in fission yeast

The EMBO journal, 1997

Transcription 'run-on' (TRO) analysis using permeabilized yeast cells indicates that transcription terminates between 180 and 380 bp downstream of the poly(A) site of the Schizosaccharomyces pombe ura4 gene. Two signals direct RNA polymerase II (pol II) to stop transcription: the ...

Termination and pausing of RNA polymerase II downstream of yeast polyadenylation sites

Molecular and Cellular Biology, 1993

Little is known about the transcriptional events which occur downstream of polyadenylation sites. Although the polyadenylation site of a gene can be easily identified, it has been difficult to determine the site of transcription termination in vivo because of the rapid processing of pre-mRNAs. Using an in vitro approach, we have shown that sequences from the 3' ends of two different Saccharomyces cerevisiae genes, ADH2 and GAL7, direct transcription termination and/or polymerase pausing in yeast nuclear extracts. In the case of the ADH2 sequence, the RNA synthesized in vitro ends approximately 50 to 150 nucleotides downstream of the poly(A) site. This RNA is not polyadenylated and may represent the primary transcript. A similarly sized nonpolyadenylated [poly(A)-] transcript can be detected in vivo from the same transcriptional template. A GAL7 template also directs the in vitro synthesis of an RNA which extends a short distance past the poly(A) site. However, a significant amou...

Transcription termination by the eukaryotic RNA polymerase III

Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013

RNA polymerase (pol) III transcribes a multitude of tRNA and 5S rRNA genes as well as other small RNA genes distributed through the genome. By being sequence-specific, precise and efficient, transcription termination by pol III not only defines the 3′ end of the nascent RNA which directs subsequent association with the stabilizing La protein, it also prevents transcription into downstream DNA and promotes efficient recycling. Each of the RNA polymerases appears to have evolved unique mechanisms to initiate the process of termination in response to different types of termination signals. However, in eukaryotes much less is known about the final stage of termination, destabilization of the elongation complex with release of the RNA and DNA from the polymerase active center. By comparison to pols I & II, pol III exhibits the most direct coupling of the initial and final stages of termination, both of which occur at a short oligo(dT) tract on the nontemplate strand (dA on the template) of the DNA. While pol III termination is autonomous involving the core subunits C2 and probably C1, it also involves subunits C11, C37 and C53, which act on the pol III catalytic center and exhibit homology to the pol II elongation factor TFIIS, and TFIIFα/β respectively. Here we compile knowledge of pol III termination and associate mutations that affect this process with structural elements of the polymerase that illustrate the importance of C53/37 both at its docking site on the pol III lobe and in the active center. The models suggest that some of these features may apply to the other eukaryotic pols.

Yeast RNase III Triggers Polyadenylation-Independent Transcription Termination

Molecular Cell, 2009

Character count: 45 735 Running title: Rnt1p dependent transcription termination Subject category: Posttranscriptional Regulation Ghazal et al., 2009 2 2 Summary Transcription termination of messenger RNA (mRNA) is normally achieved by polyadenylation followed by Rat1p dependent 5'-3' exoribonuleolytic degradation of the downstream transcript. Here we show that the yeast orthologue of the dsRNA-specific ribonuclease III (Rnt1p) may trigger Rat1p dependent termination of RNA transcripts that fail to terminate near polyadenylation signals. Rnt1p cleavage sites were found downstream of several genes and the deletion of RNT1 resulted in transcription read-through. Inactivation of Rat1p impaired Rnt1p dependent termination and resulted in the accumulation of 3' end cleavage products.

Role of the RNA/DNA kinase Grc3 in transcription termination by RNA polymerase I

EMBO reports, 2010

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Transcription termination by nuclear RNA polymerases

2009

Gene transcription in the cell nucleus is a complex and highly regulated process. Transcription in eukaryotes requires three distinct RNA polymerases, each of which employs its own mechanisms for initiation, elongation, and termination. Termination mechanisms vary considerably, ranging from relatively simple to exceptionally complex. In this review, we describe the present state of knowledge on how each of the three RNA polymerases terminates and how mechanisms are conserved, or vary, from yeast to human.