Common chaperone activity in the G-domain of trGTPase protects L11-L12 interaction on the ribosome

Nucleic Acids Res. 2012 Nov;40(21):10851-65. doi: 10.1093/nar/gks833. Epub 2012 Sep 10.

Abstract

Translational GTPases (trGTPases) regulate all phases of protein synthesis. An early event in the interaction of a trGTPase with the ribosome is the contact of the G-domain with the C-terminal domain (CTD) of ribosomal protein L12 (L12-CTD) and subsequently interacts with the N-terminal domain of L11 (L11-NTD). However, the structural and functional relationships between L12-CTD and L11-NTD remain unclear. Here, we performed mutagenesis, biochemical and structural studies to identify the interactions between L11-NTD and L12-CTD. Mutagenesis of conserved residues in the interaction site revealed their role in the docking of trGTPases. During docking, loop62 of L11-NTD protrudes into a cleft in L12-CTD, leading to an open conformation of this domain and exposure of hydrophobic core. This unfavorable situation for L12-CTD stability is resolved by a chaperone-like activity of the contacting G-domain. Our results suggest that all trGTPases-regardless of their different specific functions-use a common mechanism for stabilizing the L11-NTD•L12-CTD interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / metabolism
  • GTP Phosphohydrolase-Linked Elongation Factors / chemistry
  • GTP Phosphohydrolase-Linked Elongation Factors / metabolism
  • GTP-Binding Proteins / chemistry*
  • GTP-Binding Proteins / metabolism
  • Hydrophobic and Hydrophilic Interactions
  • Models, Molecular
  • Molecular Chaperones / chemistry*
  • Molecular Chaperones / metabolism
  • Peptide Elongation Factor G / chemistry
  • Peptide Elongation Factor G / metabolism
  • Peptide Initiation Factors
  • Protein Interaction Domains and Motifs
  • Ribosomal Proteins / chemistry*
  • Ribosomal Proteins / metabolism
  • Ribosomes / metabolism
  • Static Electricity
  • Transcriptional Elongation Factors / chemistry
  • Transcriptional Elongation Factors / metabolism

Substances

  • Escherichia coli Proteins
  • LepA protein, E coli
  • Molecular Chaperones
  • Peptide Elongation Factor G
  • Peptide Initiation Factors
  • Ribosomal Proteins
  • Transcriptional Elongation Factors
  • ribosomal protein L11
  • rplK protein, E coli
  • rplL protein, E coli
  • GTP Phosphohydrolase-Linked Elongation Factors
  • GTP-Binding Proteins