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Rapid Isolation of the Mitoribosome from HEK Cells
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Stepwise maturation of the peptidyl transferase region of human mitoribosomes

Tea Lenarčič1, Mateusz Jaskolowski1, Marc Leibundgut1

  • 1Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.

Nature Communications
|June 17, 2021
PubMed

Insights

Researchers uncovered key steps in human mitochondrial ribosome assembly, revealing how specific factors like NSUN4-MTERF4 and MTG2 ensure proper formation of the large ribosomal subunit for protein synthesis.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Mitochondrial ribosomes (mitoribosomes) synthesize crucial membrane proteins for oxidative phosphorylation.
  • Mammalian mitoribosomes exhibit significant divergence from bacterial ribosomes, with reduced ribosomal RNAs.
  • The assembly pathway of mammalian mitoribosomes remains poorly understood.

Purpose of the Study:

  • To elucidate the structural basis of human large mitoribosomal subunit assembly.
  • To identify key assembly intermediates and the factors involved.

Main Methods:

  • Analysis of eight distinct assembly intermediates of the human large mitoribosomal subunit.
  • Characterization of the roles of seven identified assembly factors.

Main Results:

  • The NSUN4-MTERF4 dimer stabilizes 16S rRNA for modification by MRM2 methyltransferase.
  • The GTPase MTG2 mediates quality control interactions with the sarcin-ricin loop and active site.
  • These factors facilitate the formation of the peptidyl transferase active site and rRNA folding.

Conclusions:

  • A sequential mechanism involving NSUN4-MTERF4 and MTG2 is critical for mitoribosome biogenesis.
  • This process ensures the correct assembly of the large mitoribosomal subunit for essential cellular functions.
  • Understanding mitoribosome assembly provides insights into mitochondrial protein synthesis and potential therapeutic targets.

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