Structure and substrate recognition by the bacterial Twin-arginine translocation (Tat) pathway core complex

Journal article

The twin-arginine translocation (Tat) system is a mechanistically unique protein transport pathway moving folded proteins across membranes. It is found in all domains of life and is essential for bacterial virulence and plant photosynthesis. The membrane proteins, TatA, TatB, and TatC form a core complex to which substrate proteins bind triggering recruitment of additional TatA protomers to form the transport site. Here we present cryoelectron microscopy structures of the prototypical TatBC complex from Escherichia coli and the atypical complexes from Nitratifactor salsuginis and Myxococcus xanthus in a resting state, alongside TatAC substrate-bound TatBC and TatABC complexes from E.coli in the early stages of transport. These structures demonstrate that substrate proteins associate with the core complex solely through their N-terminal signal peptides. The Tat targeting sequences make specific contacts with TatC and the peptide body is clamped by TatB. The core complex contains highly tilted transmembrane helices that drive extreme local membrane thinning. Based on our structures and biochemical and functional analyses, we propose a model for the early steps in Tat transport.

Authors: Deme, JC; Bryant, OJ; Batista, MRB; Stansfeld, PJ; Berks, BC

• Publication status: Accepted
• Peer review status: Peer reviewed
• Publisher: Springer Nature
• Journal: Nature Microbiology
• Acceptance date: 2026-05-07
• EISSN: 2058-5276
• Language: English