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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Centromere / genetics
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Centromere / metabolism
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Chromatin / genetics
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Chromatin / metabolism*
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Gene Expression Regulation, Fungal / physiology
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Promoter Regions, Genetic / physiology
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RNA Interference / physiology*
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RNA Polymerase II / genetics
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RNA Polymerase II / metabolism*
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RNA Processing, Post-Transcriptional / physiology
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism*
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Ribonuclease III / metabolism
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Schizosaccharomyces / physiology*
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Schizosaccharomyces pombe Proteins / genetics
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Schizosaccharomyces pombe Proteins / metabolism*
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Transcription, Genetic / physiology
Substances
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Chromatin
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RNA, Small Interfering
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Schizosaccharomyces pombe Proteins
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RNA Polymerase II
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Rpb7 protein, S pombe
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Ribonuclease III