PDBsum entry 6tqn

Transcription

PDB id: 6tqn

Contents

Protein chains

255 a.a.

495 a.a.

134 a.a.

98 a.a.

178 a.a.

322 a.a.

222 a.a.

90 a.a.

1342 a.a.

1337 a.a.

DNA/RNA

Metals

_MG ×3

_ZN ×2

References listed in PDB file

Key reference

• Title: Structure-Based mechanisms of a molecular RNA polymerase/chaperone machine required for ribosome biosynthesis.
• Authors: Y.H.Huang, T.Hilal, B.Loll, J.Bürger, T.Mielke, C.Böttcher, N.Said, M.C.Wahl.
• Ref.: Mol Cell, 2020, 79, 1024. [DOI no: 10.1016/j.molcel.2020.08.010]
• PubMed id: 32871103

Abstract

Bacterial ribosomal RNAs are synthesized by a dedicated, conserved transcription-elongation complex that transcribes at high rates, shields RNA polymerase from premature termination, and supports co-transcriptional RNA folding, modification, processing, and ribosomal subunit assembly by presently unknown mechanisms. We have determined cryo-electron microscopy structures of complete Escherichia coli ribosomal RNA transcription elongation complexes, comprising RNA polymerase; DNA; RNA bearing an N-utilization-site-like anti-termination element; Nus factors A, B, E, and G; inositol mono-phosphatase SuhB; and ribosomal protein S4. Our structures and structure-informed functional analyses show that fast transcription and anti-termination involve suppression of NusA-stabilized pausing, enhancement of NusG-mediated anti-backtracking, sequestration of the NusG C-terminal domain from termination factor ρ, and the ρ blockade. Strikingly, the factors form a composite RNA chaperone around the RNA polymerase RNA-exit tunnel, which supports co-transcriptional RNA folding and annealing of distal RNA regions. Our work reveals a polymerase/chaperone machine required for biosynthesis of functional ribosomes.