Structural basis of transcription-translation coupling and collision in bacteria

Science. 2020 Sep 11;369(6509):1355-1359. doi: 10.1126/science.abb5036. Epub 2020 Aug 20.


Prokaryotic messenger RNAs (mRNAs) are translated as they are transcribed. The lead ribosome potentially contacts RNA polymerase (RNAP) and forms a supramolecular complex known as the expressome. The basis of expressome assembly and its consequences for transcription and translation are poorly understood. Here, we present a series of structures representing uncoupled, coupled, and collided expressome states determined by cryo-electron microscopy. A bridge between the ribosome and RNAP can be formed by the transcription factor NusG, which stabilizes an otherwise-variable interaction interface. Shortening of the intervening mRNA causes a substantial rearrangement that aligns the ribosome entrance channel to the RNAP exit channel. In this collided complex, NusG linkage is no longer possible. These structures reveal mechanisms of coordination between transcription and translation and provide a framework for future study.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy
  • DNA-Directed RNA Polymerases / chemistry*
  • Escherichia coli / genetics*
  • Escherichia coli Proteins / chemistry*
  • Gene Expression Regulation, Bacterial
  • Peptide Elongation Factors / chemistry*
  • Protein Binding
  • Protein Biosynthesis*
  • Protein Conformation
  • RNA, Messenger / chemistry
  • Ribosome Subunits, Large, Bacterial / chemistry
  • Transcription Factors / chemistry*
  • Transcription, Genetic*


  • Escherichia coli Proteins
  • NusG protein, E coli
  • Peptide Elongation Factors
  • RNA, Messenger
  • Transcription Factors
  • DNA-Directed RNA Polymerases