@article{22148,
  abstract     = {How the twin-arginine translocase (Tat) system transports fully folded substrate proteins across cellular membranes without disrupting membrane integrity has been a fundamental question in cell biology for decades. The Tat system, found in prokaryotes and plant organelles, recognizes a cargo signal peptide via a conserved twin-arginine motif. The multi-subunit Tat complex facilitates the proton-motive-force-dependent translocation process, yet its overall architecture has remained unknown. Here, we present the cryo-electron microscopy (cryo-EM) structure of the Escherichia coli (E. coli) trimeric TatB₃C₃ complex with bound substrate SufI, assembled in vivo. The complex adopts an unusual, wide-open, bowl-shaped architecture with a polar inner cavity. Unexpectedly, the cargo is engaged in a dual-contact mode: while the signal peptide binds inside one TatBC unit, the folded domain docks tightly onto an adjacent unit, possibly performing a proofreading function. This structure provides a mechanistic framework for substrate engagement and suggests the direct involvement of the entire Tat complex in substrate translocation.},
  author       = {Zhao, Ziyu and Sazanov, Leonid A},
  issn         = {1097-4164},
  journal      = {Molecular Cell},
  publisher    = {Elsevier},
  title        = {{Structure of E. Coli twin-arginine translocase (Tat) complex with bound cargo}},
  doi          = {10.1016/j.molcel.2026.05.026},
  year         = {2026},
}