Download MendeleyStructural basis of RNA polymerase I pre-initiation complex formation and promoter melting.
Pilsl, M., Engel, C.(2020) Nat Commun 11: 1206-1206
- PubMed: 32139698
- DOI: https://doi.org/10.1038/s41467-020-15052-y
- Primary Citation of Related Structures:
6TPS - PubMed Abstract:
Transcription of the ribosomal RNA precursor by RNA polymerase (Pol) I is a prerequisite for the biosynthesis of ribosomes in eukaryotes. Compared to Pols II and III, the mechanisms underlying promoter recognition, initiation complex formation and DNA melting by Pol I substantially diverge. Here, we report the high-resolution cryo-EM reconstruction of a Pol I early initiation intermediate assembled on a double-stranded promoter scaffold that prevents the establishment of downstream DNA contacts. Our analyses demonstrate how efficient promoter-backbone interaction is achieved by combined re-arrangements of flexible regions in the 'core factor' subunits Rrn7 and Rrn11. Furthermore, structure-function analysis illustrates how destabilization of the melted DNA region correlates with contraction of the polymerase cleft upon transcription activation, thereby combining promoter recruitment with DNA-melting. This suggests that molecular mechanisms and structural features of Pol I initiation have co-evolved to support the efficient melting, initial transcription and promoter clearance required for high-level rRNA synthesis.
Organizational Affiliation:
Regensburg Center for Biochemistry, University of Regensburg, Regensburg, Germany.
