title: RNA Pol II subunit Rpb7 promotes centromeric transcription and RNAi-directed chromatin silencing.
abstract: Fission yeast centromeric repeats are transcribed into small interfering RNA (siRNA) precursors (pre-siRNAs), which are processed by Dicer to direct heterochromatin formation. Recently, Rpb1 and Rpb2 subunits of RNA polymerase II (RNA Pol II) were shown to mediate RNA interference (RNAi)-directed chromatin modification but did not affect pre-siRNA levels. Here we show that another Pol II subunit, Rpb7 has a specific role in pre-siRNA transcription. We define a centromeric pre-siRNA promoter from which initiation is exquisitely sensitive to the rpb7-G150D mutation. In contrast to other Pol II subunits, Rpb7 promotes pre-siRNA transcription required for RNAi-directed chromatin silencing.
authors.affiliation: Karolinska Institutet, Department of Biosciences, School of Life Sciences, University College Sodertorn, S-141 89 Huddinge, Sweden.
authors.forename: Ingela
authors.initials: I
authors.lastname: Djupedal
authors.forename: Manuela
authors.initials: M
authors.lastname: Portoso
authors.forename: Henrik
authors.initials: H
authors.lastname: Spåhr
authors.forename: Carolina
authors.initials: C
authors.lastname: Bonilla
authors.forename: Claes M
authors.initials: CM
authors.lastname: Gustafsson
authors.forename: Robin C
authors.initials: RC
authors.lastname: Allshire
authors.forename: Karl
authors.initials: K
authors.lastname: Ekwall
mesh_terms: D002503:Centromere / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000502:physiology; D034622:RNA Interference / Q000502:physiology*; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D043244:Ribonuclease III / Q000378:metabolism; D012568:Schizosaccharomyces / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D002843:Chromatin; D034741:RNA, Small Interfering; D029702:Schizosaccharomyces pombe Proteins; D012319:RNA Polymerase II; C496332:Rpb7 protein, S pombe; D043244:Ribonuclease III