Signal peptide-chaperone interactions on the twin-arginine protein transport pathway

Kostas Hatzixanthis, Thomas A. Clarke, Arthur Oubrie, David J. Richardson, Raymond J. Turner, Frank Sargent

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)


The twin-arginine transport (Tat) system is a protein-targeting pathway of prokaryotes and chloroplasts. Most Escherichia coli Tat substrates are complex metalloenzymes that must be correctly folded and assembled before transport, and a preexport chaperone-mediated “proofreading” process is therefore in operation. The paradigm proofreading chaperone is TorD, which coordinates maturation and export of the key respiratory enzyme trimethylamine N-oxide reductase (TorA). It is demonstrated here that purified TorD binds tightly and with exquisite specificity to the TorA twin-arginine signal peptide in vitro. It is also reported that the TorD family constitutes a hitherto unexpected class of nucleotide-binding proteins. The affinity of TorD for GTP is enhanced by initial signal peptide binding, and it is proposed that GTP governs signal peptide binding-and-release cycles during Tat proofreading.
Original languageEnglish
Pages (from-to)8460-8465
Number of pages6
JournalProceedings of the National Academy of Sciences
Publication statusPublished - 14 Jun 2005

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