Budding yeast RNA polymerases I and II employ parallel mechanisms of transcriptional termination.
Both RNA polymerase I and II (Pol I and Pol II) in budding yeast employ a functionally homologous "torpedo-like" mechanism to promote transcriptional termination. For two well-defined Pol II-transcribed genes, CYC1 and PMA1, we demonstrate that both Rat1p exonuclease and Sen1p helicase are required for efficient termination by promoting degradation of the nascent transcript associated with Pol II, following mRNA 3' end processing. Similarly, Pol I termination relies on prior Rnt1p cleavage at the 3' end of the pre-rRNA 35S transcript. This is followed by the combined actions of Rat1p and Sen1p to degrade the Pol I-associated nascent transcript that consequently promote termination in the downstream rDNA spacer sequence. Our data suggest that the previously defined in vitro Pol I termination mechanism involving the action of the Reb1p DNA-binding factor to "road-block" Pol I transcription close to the termination region may have overlooked more complex in vivo molecular processes.
Kawauchi
Junya
J
Sir William Dunn School of Pathology, Oxford OX1 3RE, United Kingdom.
Mischo
Hannah
H
Braglia
Priscilla
P
Rondon
Ana
A
Proudfoot
Nick J
NJ
D045304:Cytochromes c / Q000378:metabolism; D004265:DNA Helicases; D004275:DNA, Ribosomal / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D008954:Models, Biological; D006180:Proton-Translocating ATPases / Q000378:metabolism; D020365:RNA Helicases; D012318:RNA Polymerase I / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013728:Terminator Regions, Genetic / Q000235:genetics*; D014158:Transcription, Genetic
C014059:CYC1 protein, S cerevisiae; D004275:DNA, Ribosomal; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C075577:RAT1 protein, S cerevisiae; D045304:Cytochromes c; D012319:RNA Polymerase II; D012318:RNA Polymerase I; D005095:Exoribonucleases; C092477:PMA1 protein, S cerevisiae; C542347:SEN1 protein, S cerevisiae; D006180:Proton-Translocating ATPases; D004265:DNA Helicases; D020365:RNA Helicases