Transcriptional termination by RNA polymerase I requires the small subunit Rpa12p.
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 Deltarpa12, 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.
Prescott
Elizabeth M
EM
Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, United Kingdom.
Osheim
Yvonne N
YN
Jones
Hannah S
HS
Alen
Claudia M
CM
Roan
Judith G
JG
Reeder
Ronald H
RH
Beyer
Ann L
AL
Proudfoot
Nick J
NJ
D001483:Base Sequence; D017931:DNA Primers; D004275:DNA, Ribosomal / Q000235:genetics; D012318:RNA Polymerase I / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*
D017931:DNA Primers; D004275:DNA, Ribosomal; D029701:Saccharomyces cerevisiae Proteins; C423311:RPA12 protein, S cerevisiae; D012318:RNA Polymerase I