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Lookup NU author(s): Dr Jon Cherry, Dr Grant Buchanan, Professor Tracy Palmer FRS FRSE FMedSciORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2017 The Authors. The twin-arginine protein transport (Tat) machinery mediates the translocation of folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of plant chloroplasts. The Escherichia coli Tat system comprises TatC and two additional sequence-related proteins, TatA and TatB. The active translocase is assembled on demand, with substrate-binding at a TatABC receptor complex triggering recruitment and assembly ofmultiple additional copies of TatA; however, the molecular interactions mediating translocase assembly are poorly understood. A 'polar cluster'site on TatC transmembrane (TM) helix 5 was previously identified as binding to TatB. Here, we use disulfide cross-linking and molecular modelling to identify a new binding site on TatC TM helix 6, adjacent to the polar cluster site. We demonstrate that TatA and TatB each have the capacity to bind at both TatC sites, however in vivo this is regulated according to the activation state of the complex. In the resting-state system, TatB binds the polar cluster site, with TatA occupying the TM helix 6 site. However when the system is activated by overproduction of a substrate, TatA and TatB switch binding sites. We propose that this substrate-triggered positional exchange is a key step in the assembly of an active Tat translocase.
Author(s): Habersetzer J, Moore K, Cherry J, Buchanan G, Stansfeld PJ, Palmer T
Publication type: Article
Publication status: Published
Journal: Open Biology
Year: 2017
Volume: 7
Issue: 8
Online publication date: 16/08/2017
Acceptance date: 19/07/2017
Date deposited: 14/02/2019
ISSN (electronic): 2046-2441
Publisher: Royal Society Publishing
URL: https://doi.org/10.1098/rsob.170091
DOI: 10.1098/rsob.170091
PubMed id: 28814647
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