Search bioRxiv⌕ Search

Biology subjects

Merkl, P. E.

Publications and source records attributed to Merkl, P. E..

2 recordsLinked to original sources
bioRxiv2019

RNA polymerase I passage through nucleosomes depends on its lobe binding subunits

RNA polymerase I (Pol I) is a highly efficient enzyme specialized to synthesize most of the ribosomal RNA. After nucleosome deposition at each round of replication the Pol I transcription machinery has to deal with nucleosomal barriers. It was suggested that Pol I-associated factors facilitate chromatin transcription, but it is not known whether Pol I has an intrinsic capacity to transcribe through nucleosomes. Here we used in vitro transcription assays to study purified Pol I of the yeast S. cerevisiae and Pol I mutants in comparison to Pol II and Pol III to pass a nucleosome. Under identical conditions, purified Pol I and Pol III, but not Pol II, were able to 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. The contribution of Pol I specific subunit domains to efficient passage through nucleosomes in context with transcription rate and processivity is discussed.

biochemistry↗
bioRxiv2018

RNA polymerase I transcription fidelity, speed and processivity depend on the interplay of its lobe binding subunits

Eukaryotic RNA polymerases I and III (Pol I and III) consist of core subunits, which are conserved in RNA polymerase II (Pol II). Additionally, Pol I and III have specific subunits, associating with the so-called lobe structure first described within Pol II. In Pol I of the yeast S. cerevisiae, these are Rpa34.5, and the N-terminal domains of Rpa49 and Rpa12.2, here referred to as the lobe-binding module (lb-module). We analyzed functions of the lb-module in a defined in vitro transcription system. Cooperation between lb-module components influenced transcription fidelity, elongation speed, and release of stalled Pol I complexes to continue elongation. Interestingly, lb-module containing Pol I and III, but not Pol II, were able to transcribe nucleosomal templates. Our data suggest, how the Pol I specific subunits may contribute to accurate and processive transcription of ribosomal RNA genes.

biochemistry↗