Pre-termination Transcription Complex: Structure and Function

Mol Cell. 2021 Jan 21;81(2):281-292.e8. doi: 10.1016/j.molcel.2020.11.013. Epub 2020 Dec 8.


Rho is a general transcription termination factor playing essential roles in RNA polymerase (RNAP) recycling, gene regulation, and genomic stability in most bacteria. Traditional models of transcription termination postulate that hexameric Rho loads onto RNA prior to contacting RNAP and then translocates along the transcript in pursuit of the moving RNAP to pull RNA from it. Here, we report the cryoelectron microscopy (cryo-EM) structures of two termination process intermediates. Prior to interacting with RNA, Rho forms a specific "pre-termination complex" (PTC) with RNAP and elongation factors NusA and NusG, which stabilize the PTC. RNA exiting RNAP interacts with NusA before entering the central channel of Rho from the distal C-terminal side of the ring. We map the principal interactions in the PTC and demonstrate their critical role in termination. Our results support a mechanism in which the formation of a persistent PTC is a prerequisite for termination.

Keywords: RNA polymerase, transcription termination, Rho, NusA, NusG, elongation complex, Cryo-EM.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Cloning, Molecular
  • Cryoelectron Microscopy
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • DNA-Directed RNA Polymerases / chemistry*
  • DNA-Directed RNA Polymerases / genetics
  • DNA-Directed RNA Polymerases / metabolism
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • Models, Molecular
  • Peptide Elongation Factors / chemistry*
  • Peptide Elongation Factors / genetics
  • Peptide Elongation Factors / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Protein Conformation, beta-Strand
  • Protein Interaction Domains and Motifs
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / genetics
  • RNA, Bacterial / metabolism
  • Transcription Factors / chemistry*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription Termination, Genetic*
  • Transcriptional Elongation Factors / chemistry*
  • Transcriptional Elongation Factors / genetics
  • Transcriptional Elongation Factors / metabolism


  • DNA, Bacterial
  • Escherichia coli Proteins
  • NusG protein, E coli
  • Peptide Elongation Factors
  • Protein Subunits
  • RNA, Bacterial
  • Rho protein, E coli
  • Transcription Factors
  • Transcriptional Elongation Factors
  • nusA protein, E coli
  • DNA-Directed RNA Polymerases