Dynamic action of the Sec machinery during initiation, protein translocation and termination
- University of Leeds, United Kingdom
- University of Bristol, United Kingdom
Abstract
Protein translocation across cell membranes is a ubiquitous process required for protein secretion and membrane protein insertion. In bacteria, this is mostly mediated by the conserved SecYEG complex, driven through rounds of ATP hydrolysis by the cytoplasmic SecA, and the trans-membrane proton motive force. We have used single molecule techniques to explore SecY pore dynamics on multiple timescales in order to dissect the complex reaction pathway. The results show that SecA, both the signal sequence and mature components of the pre-protein, and ATP hydrolysis each have important and specific roles in channel unlocking, opening and priming for transport. After channel opening, translocation proceeds in two phases: a slow phase independent of substrate length, and a length-dependent transport phase with an intrinsic translocation rate of ~40 amino acids per second for the proOmpA substrate. Broad translocation rate distributions reflect the stochastic nature of polypeptide transport.
Data availability
Compressed data are available together with the relevant scripts as Supplementary Source Data and Code
Article and author information
Author details
William John Allen
Funding
Biotechnology and Biological Sciences Research Council (BB/N017307/1)
- Tomas Fessl
- Sheena E Radford
- Roman Tuma
Biotechnology and Biological Sciences Research Council (BB/I008675/1)
- Daniel Watkins
Biotechnology and Biological Sciences Research Council (BB/M003604/I)
- Robin Adam Corey
Wellcome (104632)
- William John Allen
- Ian Collinson
Seventh Framework Programme (32240)
- Sheena E Radford
European Regional Development Fund (CZ.02.1.01/0.0/0.0/15_003/0000441)
- Tomas Fessl
- Roman Tuma
Biotechnology and Biological Sciences Research Council (BB/N015126/1)
- Daniel Watkins
- Ian Collinson
Biotechnology and Biological Sciences Research Council (BB/I008675/1)
- Peter Oatley
- Steve A Baldwin
- Sheena E Radford
- Roman Tuma
Biotechnology and Biological Sciences Research Council (BB/M011151/1)
- Jim Horne
Biotechnology and Biological Sciences Research Council (BB/I006737/1)
- William John Allen
- Ian Collinson
Biotechnology and Biological Sciences Research Council (BBSRC South West Bioscience Doctoral Training Partnership)
- Robin Adam Corey
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Fessl 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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Dynamic action of the Sec machinery during initiation, protein translocation and termination
eLife 7:e35112.
https://doi.org/10.7554/eLife.35112
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