Chemical and structural characterization of a model Post-Termination Complex (PoTC) for the ribosome recycling reaction: Evidence for the release of the mRNA by RRF and EF-G

PLoS One. 2017 May 24;12(5):e0177972. doi: 10.1371/journal.pone.0177972. eCollection 2017.

Abstract

A model Post-Termination Complex (PoTC) used for the discovery of Ribosome Recycling Factor (RRF) was purified and characterized by cryo-electron microscopic analysis and biochemical methods. We established that the model PoTC has mostly one tRNA, at the P/E or P/P position, together with one mRNA. The structural studies were supported by the biochemical measurement of bound tRNA and mRNA. Using this substrate, we establish that the release of tRNA, release of mRNA and splitting of ribosomal subunits occur during the recycling reaction. Order of these events is tRNA release first followed by mRNA release and splitting almost simultaneously. Moreover, we demonstrate that IF3 is not involved in any of the recycling reactions but simply prevents the re-association of split ribosomal subunits. Our finding demonstrates that the important function of RRF includes the release of mRNA, which is often missed by the use of a short ORF with the Shine-Dalgarno sequence near the termination site.

MeSH terms

  • Cryoelectron Microscopy
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism*
  • Peptide Chain Termination, Translational / genetics*
  • Peptide Elongation Factor G / metabolism*
  • Peptide Termination Factors / metabolism*
  • Prokaryotic Initiation Factor-3 / metabolism
  • RNA, Messenger / metabolism
  • RNA, Transfer / metabolism
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism*

Substances

  • Peptide Elongation Factor G
  • Peptide Termination Factors
  • Prokaryotic Initiation Factor-3
  • RNA, Messenger
  • Ribosomal Proteins
  • ribosome releasing factor
  • RNA, Transfer

Grants and funding

This work was supported by funding from Creative Biomedical Research Institute, Philadelphia, (PA). FQ is a PhD student of the University of Camerino, Camerino, Italy.