YidC and Oxa1 form dimeric insertion pores on the translating ribosome

Mol Cell. 2009 May 15;34(3):344-53. doi: 10.1016/j.molcel.2009.04.019.


The YidC/Oxa1/Alb3 family of membrane proteins facilitates the insertion and assembly of membrane proteins in bacteria, mitochondria, and chloroplasts. Here we present the structures of both Escherichia coli YidC and Saccharomyces cerevisiae Oxa1 bound to E. coli ribosome nascent chain complexes determined by cryo-electron microscopy. Dimers of YidC and Oxa1 are localized above the exit of the ribosomal tunnel. Crosslinking experiments show that the ribosome specifically stabilizes the dimeric state. Functionally important and conserved transmembrane helices of YidC and Oxa1 were localized at the dimer interface by cysteine crosslinking. Both Oxa1 and YidC dimers contact the ribosome at ribosomal protein L23 and conserved rRNA helices 59 and 24, similarly to what was observed for the nonhomologous SecYEG translocon. We suggest that dimers of the YidC and Oxa1 proteins form insertion pores and share a common overall architecture with the SecY monomer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cysteine / chemistry
  • Cysteine / metabolism
  • Dimerization
  • Electron Transport Complex IV / chemistry*
  • Electron Transport Complex IV / genetics
  • Electron Transport Complex IV / metabolism*
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Membrane Transport Proteins / chemistry*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Mitochondrial Proteins / chemistry*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • Models, Molecular
  • Multiprotein Complexes / metabolism*
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Oxidation-Reduction
  • Protein Binding
  • Protein Biosynthesis
  • Protein Structure, Quaternary*
  • Ribosomes / genetics
  • Ribosomes / metabolism*
  • SEC Translocation Channels


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Membrane Transport Proteins
  • Mitochondrial Proteins
  • Multiprotein Complexes
  • Nuclear Proteins
  • OXA1 protein
  • SEC Translocation Channels
  • SecY protein, E coli
  • YIDC protein, E coli
  • Electron Transport Complex IV
  • Cysteine