Yeast Mitoribosome Large Subunit Assembly Proceeds by Hierarchical Incorporation of Protein Clusters and Modules on the Inner Membrane

Rui Zeng, Erin Smith, Antoni Barrientos

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Mitoribosomes are specialized for the synthesis of hydrophobic membrane proteins encoded by mtDNA, all essential for oxidative phosphorylation. Despite their linkage to human mitochondrial diseases and the recent cryoelectron microscopy reconstruction of yeast and mammalian mitoribosomes, how they are assembled remains obscure. Here, we dissected the yeast mitoribosome large subunit (mtLSU) assembly process by systematic genomic deletion of 44 mtLSU proteins (MRPs). Analysis of the strain collection unveiled 37 proteins essential for functional mtLSU assembly, three of which are critical for mtLSU 21S rRNA stability. Hierarchical cluster analysis of mtLSU subassemblies accumulated in mutant strains revealed co-operative assembly of protein sets forming structural clusters and preassembled modules. It also indicated crucial roles for mitochondrion-specific membrane-binding MRPs in anchoring newly transcribed 21S rRNA to the inner membrane, where assembly proceeds. Our results define the yeast mtLSU assembly landscape in vivo and provide a foundation for studies of mitoribosome assembly across evolution. Despite the biomedical relevance of the mitochondrial protein synthesis machinery, how mitoribosome biogenesis occurs remains largely unknown. By systematic deletion of 44 mitoribosome proteins in yeast, Zeng et al. describe a mitoribosome subunit assembly pathway, which occurs in contact with the mitochondrial inner membrane and involves hierarchical incorporation of protein clusters and modules.

Original languageEnglish (US)
Pages (from-to)645-656.e7
JournalCell Metabolism
Issue number3
StatePublished - Mar 6 2018


  • 54S mitoribosome large subunit
  • co-translational membrane insertion
  • mitochondrial disease
  • mitochondrial protein synthesis
  • mitochondrial ribosome
  • mitoribosome 21S rRNA
  • mitoribosome assembly
  • mitoribosome membrane anchoring

ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Cell Biology


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