A subset of bacterial inner membrane proteins integrated by the twin-arginine translocase

Kostas Hatzixanthis, Tracy Palmer, Frank Sargent

    Research output: Contribution to journalArticlepeer-review

    103 Citations (Scopus)


    A group of bacterial exported proteins are synthesized with N-terminal signal peptides containing a SRRxFLK ‘twin-arginine’ amino acid motif. Proteins bearing twin-arginine signal peptides are targeted post-translationally to the twin-arginine translocation (Tat) system which transports folded substrates across the inner membrane. In Escherichia coli, most integral inner membrane proteins are assembled by a co-translational process directed by SRP/FtsY, the SecYEG translocase, and YidC. In this work we define a novel class of integral membrane proteins assembled by a Tat-dependent mechanism. We show that at least five E. coli Tat substrate proteins contain hydrophobic C-terminal transmembrane helices (or ‘C-tails’). Fusions between the identified transmembrane C-tails and the exclusively Tat-dependent reporter proteins TorA and SufI render the resultant chimeras membrane-bound. Export-linked signal peptide processing and membrane integration of the chimeras is shown to be both Tat-dependent and YidC-independent. It is proposed that the mechanism of membrane integration of proteins by the Tat system is fundamentally distinct from that employed for other bacterial inner membrane proteins.
    Original languageEnglish
    Pages (from-to)1377-1390
    Number of pages14
    JournalMolecular Microbiology
    Issue number5
    Publication statusPublished - 2003


    • Twin arginine signal peptide
    • Tat pathway
    • Protein transport
    • Bacterial transport


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