Allosteric signalling in the outer membrane translocation domain of PapC usher
- Birkbeck College, United Kingdom
- University of Houston, United States
- Stony Brook University, United States
- University of Würzburg, Germany
- Université Paris Descartes, France
Abstract
PapC ushers are outer-membrane proteins enabling assembly and secretion of P pili in uropathogenic E. coli. Their translocation domain is a large β-barrel occluded by a plug domain, which is displaced to allow the translocation of pilus subunits across the membrane. Previous studies suggested that this gating mechanism is controlled by a β-hairpin and an α-helix. To investigate the role of these elements in allosteric signal communication we developed a method combining evolutionary and molecular dynamics studies of the native translocation domain and mutants lacking the β-hairpin and/or α-helix. Analysis of a hybrid residue interaction network suggests distinct regions (residue 'communities') within the translocation domain (especially around β12-β14) linking these elements, thereby modulating PapC gating. Antibiotic sensitivity and electrophysiology experiments on a set of alanine-substitution mutants confirmed functional roles for four of these communities. This study illuminates the gating mechanism of PapC ushers and its importance in maintaining outer-membrane permeability.
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Author details
Reviewing Editor
- Volker Dötsch, Goethe University, Germany
Version history
- Received: May 30, 2014
- Accepted: September 29, 2014
- Accepted Manuscript published: October 1, 2014 (version 1)
- Version of Record published: October 28, 2014 (version 2)
- Version of Record updated: September 27, 2016 (version 3)
Copyright
© 2014, Farabella 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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Allosteric signalling in the outer membrane translocation domain of PapC usher
eLife 3:e03532.
https://doi.org/10.7554/eLife.03532
Further reading
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- Cell Biology
- Structural Biology and Molecular Biophysics
Acetylation of α-tubulin at the lysine 40 residue (αK40) by αTAT1/MEC-17 acetyltransferase modulates microtubule properties and occurs in most eukaryotic cells. Previous literatures suggest that acetylated microtubules are more stable and damage resistant. αK40 acetylation is the only known microtubule luminal post-translational modification site. The luminal location suggests that the modification tunes the lateral interaction of protofilaments inside the microtubule. In this study, we examined the effect of tubulin acetylation on the doublet microtubule (DMT) in the cilia of Tetrahymena thermophila using a combination of cryo-electron microscopy, molecular dynamics, and mass spectrometry. We found that αK40 acetylation exerts a small-scale effect on the DMT structure and stability by influencing the lateral rotational angle. In addition, comparative mass spectrometry revealed a link between αK40 acetylation and phosphorylation in cilia.
