The mechanism of Tat-dependent protein translocation

Authors:

Thomas Brüser1,* and Carsten Sanders2,3,4

doi: 10.15698/mic2026.05.875
Volume 13, pp. 169 to 185, published 15/05/2026.

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Affiliations:

1 Institute of Microbiology, Leibniz University Hannover, 30419 Hannover, Germany. 2 Department of Biology, Millersville University, Millersville, PA 17551, USA. 3 Department of Biology and Integrative Science, School of Science, Engineering and Technology, Penn State Harrisburg, Middletown, PA 17057, USA. 4 Chemistry Division, Penn State York, York, PA 17403, USA.

Keywords: 

twin-arginine translocation, protein transport, membrane proteins, protein interactions, biological membranes, transport energetization

Corresponding Author(s):

Thomas Brüser, Institute of Microbiology, Leibniz University Hannover, Herrenhäuser Str. 1, 30419 Hannover, Germany; brueser@ifmb.uni-hannover.de

Conflict of interest statement:

The authors declare no conflict of interest.

Please cite this article as:

Thomas Brüser, Carsten Sanders (2026). The mechanism of Tat-dependent protein translocation. Microbial Cell 13: 169-185. doi: 10.15698/mic2026.05.875

© 2026 Brüser and Sanders. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.

Abstract:

The twin-arginine translocation (Tat) system is the only general pathway for the transport of folded proteins across energized biological membranes. It is found in the bacterial or archaeal cytoplasmic membrane, the plant thylakoid membrane or the inner membrane of plant mitochondria. The biological importance of this translocation system can be exemplified by the fact that all bacterial or plant photosynthesis and photosynthetic oxygen evolution on earth requires this system. Despite many biochemical and biophysical studies, the Tat mechanism has been puzzling since the system was discovered in the 1990ies. Important characteristics of the Tat system could not be explained, and also recent highresolution structures of the Tat system’s core with bound substrate has not led to a general transport mechanism yet. In this integrative review, we attempted to answer the key open questions relevant to the Tat mechanism and thereby developed an in its molecular detail new comprehensive explanation of how folded proteins are translocated across membranes by the Tat system.