SecA interacts with ribosomes in order to facilitate posttranslational translocation in bacteria

Damon Huber, Nandhakishore Rajagopalan, Steffen Preissler, Mark A Rocco, Frieder Merz, Günter Kramer, Bernd Bukau

Research output: Contribution to journalArticlepeer-review

67 Citations (Scopus)


In Escherichia coli, translocation of exported proteins across the cytoplasmic membrane is dependent on the motor protein SecA and typically begins only after synthesis of the substrate has already been completed (i.e., posttranslationally). Thus, it has generally been assumed that the translocation machinery also recognizes its protein substrates posttranslationally. Here we report a specific interaction between SecA and the ribosome at a site near the polypeptide exit channel. This interaction is mediated by conserved motifs in SecA and ribosomal protein L23, and partial disruption of this interaction in vivo by introducing mutations into the genes encoding SecA or L23 affects the efficiency of translocation by the posttranslational pathway. Based on these findings, we propose that SecA could interact with its nascent substrates during translation in order to efficiently channel them into the "posttranslational" translocation pathway.
Original languageEnglish
Pages (from-to)343-53
Number of pages11
JournalMolecular Cell
Issue number3
Publication statusPublished - 4 Feb 2011

Bibliographical note

Copyright © 2011 Elsevier Inc. All rights reserved.


  • Membrane Transport Proteins
  • Models, Molecular
  • Ribosomes
  • Amino Acid Sequence
  • Protein Binding
  • Binding Sites
  • Bacterial Proteins
  • Transcription Factors
  • Sequence Alignment
  • Conserved Sequence
  • Escherichia coli Proteins
  • Escherichia coli
  • Molecular Sequence Data
  • Adenosine Triphosphatases
  • Protein Structure, Tertiary
  • Mutation
  • Protein Transport


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