EF-G2mt Is an Exclusive Recycling Factor in Mammalian Mitochondrial Protein Synthesis

Masafumi Tsuboi, Hiroyuki Morita, Yusuke Nozaki, Kenta Akama, Takuya Ueda, Koichi Ito, Knud H. Nierhaus, Nono Takeuchi

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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).

Original languageEnglish
Pages (from-to)502-510
Number of pages9
JournalMolecular Cell
Issue number4
Publication statusPublished - 2009 Aug 28
Externally publishedYes



  • RNA

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Tsuboi, M., Morita, H., Nozaki, Y., Akama, K., Ueda, T., Ito, K., Nierhaus, K. H., & Takeuchi, N. (2009). EF-G2mt Is an Exclusive Recycling Factor in Mammalian Mitochondrial Protein Synthesis. Molecular Cell, 35(4), 502-510. https://doi.org/10.1016/j.molcel.2009.06.028