RNA polymerase I (Pol I) passage through nucleosomes depends on Pol I subunits binding its lobe structure
Philipp Merkl, Michael Pilsl, Tobias Fremter, Katrin Schwank, Christoph Engel, Gernot Längst, Philipp Milkereit, Joachim Griesenbeck, Herbert Tschochner
Abstract
and compare their abilities to pass a nucleosomal barrier with those of yeast Pol II and Pol III. Under identical conditions, purified Pol I and Pol III, but not Pol II, could transcribe nucleosomal templates. Pol I mutants lacking either the heterodimeric subunit Rpa34.5/Rpa49 or the C-terminal part of the specific subunit Rpa12.2 showed a lower processivity on naked DNA templates, which was even more reduced in the presence of a nucleosome. Our findings suggest that the lobe-binding subunits Rpa34.5/Rpa49 and Rpa12.2 facilitate passage through nucleosomes, suggesting possible cooperation among these subunits. We discuss the contribution of Pol I-specific subunit domains to efficient Pol I passage through nucleosomes in the context of transcription rate and processivity.