Distinct mechanisms of the human mitoribosome recycling and antibiotic resistance

Nat Commun. 2021 Jun 14;12(1):3607. doi: 10.1038/s41467-021-23726-4.

Abstract

Ribosomes are recycled for a new round of translation initiation by dissociation of ribosomal subunits, messenger RNA and transfer RNA from their translational post-termination complex. Here we present cryo-EM structures of the human 55S mitochondrial ribosome (mitoribosome) and the mitoribosomal large 39S subunit in complex with mitoribosome recycling factor (RRFmt) and a recycling-specific homolog of elongation factor G (EF-G2mt). These structures clarify an unusual role of a mitochondria-specific segment of RRFmt, identify the structural distinctions that confer functional specificity to EF-G2mt, and show that the deacylated tRNA remains with the dissociated 39S subunit, suggesting a distinct sequence of events in mitoribosome recycling. Furthermore, biochemical and structural analyses reveal that the molecular mechanism of antibiotic fusidic acid resistance for EF-G2mt is markedly different from that of mitochondrial elongation factor EF-G1mt, suggesting that the two human EF-Gmts have evolved diversely to negate the effect of a bacterial antibiotic.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cryoelectron Microscopy
  • Drug Resistance, Microbial / genetics*
  • Humans
  • Mitochondria
  • Mitochondrial Ribosomes / chemistry*
  • Mitochondrial Ribosomes / drug effects
  • Mitochondrial Ribosomes / metabolism*
  • Models, Molecular
  • Peptide Elongation Factor G / chemistry
  • Peptide Elongation Factor G / genetics
  • Peptide Elongation Factor G / metabolism
  • Protein Conformation
  • Protein Conformation, alpha-Helical
  • Protein Domains
  • RNA, Transfer / chemistry
  • RNA, Transfer / metabolism
  • Ribosomal Proteins / chemistry
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism
  • Ribosomes / chemistry*
  • Ribosomes / genetics
  • Ribosomes / metabolism*

Substances

  • Peptide Elongation Factor G
  • Ribosomal Proteins
  • RNA, Transfer