A conserved proline switch on the ribosome facilitates the recruitment and binding of trGTPases

Nat Struct Mol Biol. 2012 Mar 11;19(4):403-10. doi: 10.1038/nsmb.2254.


When elongation factor G (EF-G) binds to the ribosome, it first makes contact with the C-terminal domain (CTD) of L12 before interacting with the N-terminal domain (NTD) of L11. Here we have identified a universally conserved residue, Pro22 of L11, that functions as a proline switch (PS22), as well as the corresponding center of peptidyl-prolyl cis-trans isomerase (PPIase) activity on EF-G that drives the cis-trans isomerization of PS22. Only the cis configuration of PS22 allows direct contact between the L11 NTD and the L12 CTD. Mutational analyses of both PS22 and the residues of the EF-G PPIase center reveal their function in translational GTPase (trGTPase) activity, protein synthesis and cell survival in Escherichia coli. Finally, we demonstrate that all known universal trGTPases contain an active PPIase center. Our observations suggest that the cis-trans isomerization of the L11 PS22 is a universal event required for an efficient turnover of trGTPases throughout the translation process.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Conserved Sequence
  • Escherichia coli / chemistry
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism*
  • GTP Phosphohydrolases / chemistry
  • GTP Phosphohydrolases / metabolism*
  • Guanosine Triphosphate / metabolism
  • Isomerism
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Elongation Factor G / chemistry
  • Peptide Elongation Factor G / metabolism*
  • Peptidylprolyl Isomerase / chemistry
  • Peptidylprolyl Isomerase / metabolism
  • Proline / analysis
  • Proline / metabolism*
  • Ribosomes / chemistry
  • Ribosomes / metabolism*
  • Sequence Alignment


  • Escherichia coli Proteins
  • Peptide Elongation Factor G
  • Guanosine Triphosphate
  • Proline
  • GTP Phosphohydrolases
  • Peptidylprolyl Isomerase