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RNA Pol II subunit Rpb7 promotes centromeric transcription and RNAi-directed chromatin silencing

2005; Cold Spring Harbor Laboratory Press; Volume: 19; Issue: 19 Linguagem: Inglês

10.1101/gad.344205

1549-5477

Ingela Djupedal, Manuela Portoso, Henrik Spåhr, Carolina Bonilla, Claes M. Gustafsson, Robin C. Allshire, Karl Ekwall,

Genomics and Chromatin Dynamics

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.