Chaperone properties of mammalian mitochondrial translation elongation factor Tu

J Biol Chem. 2007 Feb 9;282(6):4076-84. doi: 10.1074/jbc.M608187200. Epub 2006 Nov 27.


The main function of the prokaryotic translation elongation factor Tu (EF-Tu) and its eukaryotic counterpart eEF1A is to deliver aminoacyl-tRNA to the A-site on the ribosome. In addition to this primary function, it has been reported that EF-Tu from various sources has chaperone activity. At present, little information is available about the chaperone activity of mitochondrial EF-Tu. In the present study, we have examined the chaperone function of mammalian mitochondrial EF-Tu (EF-Tumt). We demonstrate that recombinant EF-Tumt prevents thermal aggregation of proteins and enhances protein refolding in vitro and that this EF-Tumt chaperone activity proceeds in a GTP-independent manner. We also demonstrate that, under heat stress, the newly synthesized peptides from the mitochondrial ribosome specifically co-immunoprecipitate with EF-Tumt and are destabilized in EF-Tumt-overexpressing cells. We show that most of the EF-Tumt localizes on the mitochondrial inner membrane where most mitochondrial ribosomes are found. We discuss the possible role of EF-Tumt chaperone activity in protein quality control in mitochondria, with regard to the recently reported in vivo chaperone function of eEF1A.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Cell Line
  • Guanosine Triphosphate / physiology
  • HeLa Cells
  • Humans
  • Mitochondria / genetics
  • Mitochondria / physiology
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / physiology*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / physiology*
  • Peptide Elongation Factor Tu / genetics
  • Peptide Elongation Factor Tu / physiology*
  • Peptides / genetics
  • Peptides / physiology
  • Protein Biosynthesis*
  • Protein Folding
  • Recombinant Proteins / genetics


  • Mitochondrial Proteins
  • Molecular Chaperones
  • Peptides
  • Recombinant Proteins
  • Guanosine Triphosphate
  • Peptide Elongation Factor Tu