PDBsum entry 6tps

Transcription

PDB id: 6tps

Contents

Protein chains

1475 a.a.

1177 a.a.

305 a.a.

58 a.a.

212 a.a.

100 a.a.

193 a.a.

131 a.a.

73 a.a.

69 a.a.

101 a.a.

43 a.a.

105 a.a.

145 a.a.

463 a.a.

595 a.a.

461 a.a.

325 a.a.

DNA/RNA

Metals

_MG

_ZN ×7

References listed in PDB file

Key reference

• Title: Structural basis of RNA polymerase i pre-Initiation complex formation and promoter melting.
• Authors: M.Pilsl, C.Engel.
• Ref.: Nat Commun, 2020, 11, 1206. [DOI no: 10.1038/s41467-020-15052-y]
• PubMed id: 32139698

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.