Mechanism for the Regulated Control of Bacterial Transcription Termination by a Universal Adaptor Protein

Mol Cell. 2018 Sep 20;71(6):911-922.e4. doi: 10.1016/j.molcel.2018.07.014. Epub 2018 Aug 16.


NusG/Spt5 proteins are the only transcription factors utilized by all cellular organisms. In enterobacteria, NusG antagonizes the transcription termination activity of Rho, a hexameric helicase, during the synthesis of ribosomal and actively translated mRNAs. Paradoxically, NusG helps Rho act on untranslated transcripts, including non-canonical antisense RNAs and those arising from translational stress; how NusG fulfills these disparate functions is unknown. Here, we demonstrate that NusG activates Rho by assisting helicase isomerization from an open-ring, RNA-loading state to a closed-ring, catalytically active translocase. A crystal structure of closed-ring Rho in complex with NusG reveals the physical basis for this activation and further explains how Rho is excluded from translationally competent RNAs. This study demonstrates how a universally conserved transcription factor acts to modulate the activity of a ring-shaped ATPase motor and establishes how the innate sequence bias of a termination factor can be modulated to silence pervasive, aberrant transcription.

Keywords: ATPase; NusG; Rho; Spt5; termination; transcription; translation.

Publication types

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

MeSH terms

  • Bacterial Proteins
  • Chromosomal Proteins, Non-Histone / physiology*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / metabolism
  • Escherichia coli Proteins / physiology*
  • Models, Molecular
  • Peptide Elongation Factors / metabolism
  • Peptide Elongation Factors / physiology*
  • Protein Conformation
  • RNA, Bacterial
  • Rho Factor / metabolism
  • Rho Factor / physiology
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transcription Termination, Genetic / physiology*
  • Transcription, Genetic / genetics
  • Transcription, Genetic / physiology
  • Transcriptional Elongation Factors / physiology*


  • Bacterial Proteins
  • Chromosomal Proteins, Non-Histone
  • Escherichia coli Proteins
  • NusG protein, E coli
  • Peptide Elongation Factors
  • RNA, Bacterial
  • Rho Factor
  • Transcription Factors
  • Transcriptional Elongation Factors
  • SPT5 transcriptional elongation factor