Structural mechanism of ATP-independent transcription initiation by RNA polymerase I.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28623663.
- Also identified by DOI 10.7554/eLife.27414 and PMC identifier 5489313.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Transcription initiation by RNA Polymerase I (Pol I) depends on the Core Factor (CF) complex to recognize the upstream promoter and assemble into a Pre-Initiation Complex (PIC). Here, we solve a structure of <i>Saccharomyces cerevisiae</i> Pol I-CF-DNA to 3.8 Å resolution using single-particle cryo-electron microscopy. The structure reveals a bipartite architecture of Core Factor and its recognition of the promoter from -27 to -16. Core Factor's intrinsic mobility correlates well with different conformational states of the Pol I cleft, in addition to the stabilization of either Rrn7 N-terminal domain near Pol I wall or the tandem winged helix domain of A49 at a partially overlapping location. Comparison of the three states in this study with the Pol II system suggests that a ratchet motion of the Core Factor-DNA sub-complex at upstream facilitates promoter melting in an ATP-independent manner, distinct from a DNA translocase actively threading the downstream DNA in the Pol II PIC.
Medical subject headings
- DNA, Fungal
- Pol1 Transcription Initiation Complex Proteins
- RNA Polymerase I
- Saccharomyces cerevisiae
- Saccharomyces cerevisiae Proteins
- Transcription Initiation, Genetic