Assembling the Tat protein translocase
- University of Oxford, United Kingdom
- Kings College London, United Kingdom
- University of Dundee, United Kingdom
- University of New South Wales, Australia
Abstract
The twin-arginine protein translocation system (Tat) transports folded proteins across the bacterial cytoplasmic membrane and the thylakoid membranes of plant chloroplasts. The Tat transporter is assembled from multiple copies of the membrane proteins TatA, TatB, and TatC. We combine sequence co-evolution analysis, molecular simulations, and experimentation to define the interactions between the Tat proteins of Escherichia coli at molecular-level resolution. In the TatBC receptor complex the transmembrane helix of each TatB molecule is sandwiched between two TatC molecules, with one of the inter-subunit interfaces incorporating a functionally important cluster of interacting polar residues. Unexpectedly, we find that TatA also associates with TatC at the polar cluster site. Our data provide a structural model for assembly of the active Tat translocase in which substrate binding triggers replacement of TatB by TatA at the polar cluster site. Our work demonstrates the power of co-evolution analysis to predict protein interfaces in multi-subunit complexes.
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Author details
Funding
Biotechnology and Biological Sciences Research Council (BB/L002531/1)
- Tracy Palmer
- Ben C Berks
Wellcome (Investigator Award 107929/Z/15/Z)
- Ben C Berks
Medical Research Council (G1001640)
- Tracy Palmer
- Ben C Berks
European Commission (Marie Curie Fellowship Programme: GP7-PEOPLE-2013-IEF 626436)
- Hajra Basit
- Mark I Wallace
Biotechnology and Biological Sciences Research Council (BB/I019855/1)
- Phillip J Stansfeld
Wellcome (Investigator Award 110183/Z/15/Z)
- Tracy Palmer
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Alcock et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Assembling the Tat protein translocase
eLife 5:e20718.
https://doi.org/10.7554/eLife.20718
