Following movement of domain IV of elongation factor G during ribosomal translocation

Proc Natl Acad Sci U S A. 2014 Oct 21;111(42):15060-5. doi: 10.1073/pnas.1410873111. Epub 2014 Oct 6.

Abstract

Translocation of mRNA and tRNAs through the ribosome is catalyzed by a universally conserved elongation factor (EF-G in prokaryotes and EF-2 in eukaryotes). Previous studies have suggested that ribosome-bound EF-G undergoes significant structural rearrangements. Here, we follow the movement of domain IV of EF-G, which is critical for the catalysis of translocation, relative to protein S12 of the small ribosomal subunit using single-molecule FRET. We show that ribosome-bound EF-G adopts distinct conformations corresponding to the pre- and posttranslocation states of the ribosome. Our results suggest that, upon ribosomal translocation, domain IV of EF-G moves toward the A site of the small ribosomal subunit and facilitates the movement of peptidyl-tRNA from the A to the P site. We found no evidence of direct coupling between the observed movement of domain IV of EF-G and GTP hydrolysis. In addition, our results suggest that the pretranslocation conformation of the EF-G-ribosome complex is significantly less stable than the posttranslocation conformation. Hence, the structural rearrangement of EF-G makes a considerable energetic contribution to promoting tRNA translocation.

Keywords: ribosome; single-molecule FRET; tRNA translocation; viomycin.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Biological Transport
  • Catalysis
  • Fluorescence Resonance Energy Transfer
  • Guanosine Triphosphate / chemistry
  • Microscopy
  • Peptide Elongation Factor G / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Synthesis Inhibitors / chemistry
  • Protein Transport
  • RNA, Messenger / metabolism
  • RNA, Transfer / chemistry
  • Ribosomes / chemistry
  • Ribosomes / metabolism*
  • Viomycin / chemistry

Substances

  • Peptide Elongation Factor G
  • Protein Synthesis Inhibitors
  • RNA, Messenger
  • Guanosine Triphosphate
  • RNA, Transfer
  • Viomycin