EF-G2mt is an exclusive recycling factor in mammalian mitochondrial protein synthesis

Mol Cell. 2009 Aug 28;35(4):502-10. doi: 10.1016/j.molcel.2009.06.028.

Abstract

Bacterial translation elongation factor G (EF-G) catalyzes translocation during peptide elongation and mediates ribosomal disassembly during ribosome recycling in concert with the ribosomal recycling factor (RRF). Two homologs of EF-G have been identified in mitochondria from yeast to man, EF-G1mt and EF-G2mt. Here, we demonstrate that the dual function of bacterial EF-G is divided between EF-G1mt and EF-G2mt in human mitochondria (RRFmt). EF-G1mt specifically catalyzes translocation, whereas EF-G2mt mediates ribosome recycling with human mitochondrial RRF but lacks translocation activity. Domain swapping experiments suggest that the functional specificity for EF-G2mt resides in domains III and IV. Furthermore, GTP hydrolysis by EF-G2mt is not necessary for ribosomal splitting, in contrast to the bacterial-recycling mode. Because EF-G2mt represents a class of translational GTPase that is involved in ribosome recycling, we propose to rename this factor mitochondrial ribosome recycling factor 2 (RRF2mt).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Guanosine Triphosphate / metabolism
  • Humans
  • Hydrolysis
  • Mitochondria / metabolism*
  • Mitochondrial Proteins / biosynthesis*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Peptide Chain Elongation, Translational*
  • Peptide Elongation Factor G / genetics
  • Peptide Elongation Factor G / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport
  • Recombinant Proteins / metabolism
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism*
  • Swine

Substances

  • GFM2 protein, human
  • Mitochondrial Proteins
  • Peptide Elongation Factor G
  • Recombinant Proteins
  • Ribosomal Proteins
  • ribosome releasing factor
  • Guanosine Triphosphate