Goyal, P;
Krasteva, PV;
Van Gerven, N;
Gubellini, F;
Van den Broeck, I;
Troupiotis-Tsaïlaki, A;
Jonckheere, W;
... Remaut, H; + view all
(2014)
Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG.
[Letter].
Nature
, 516
pp. 250-253.
10.1038/nature13768.
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Abstract
Curli are functional amyloid fibres that constitute the major protein component of the extracellular matrix in pellicle biofilms formed by Bacteroidetes and Proteobacteria (predominantly of the α and γ classes). They provide a fitness advantage in pathogenic strains and induce a strong pro-inflammatory response during bacteraemia. Curli formation requires a dedicated protein secretion machinery comprising the outer membrane lipoprotein CsgG and two soluble accessory proteins, CsgE and CsgF. Here we report the X-ray structure of Escherichia coli CsgG in a non-lipidated, soluble form as well as in its native membrane-extracted conformation. CsgG forms an oligomeric transport complex composed of nine anticodon-binding-domain-like units that give rise to a 36-stranded β-barrel that traverses the bilayer and is connected to a cage-like vestibule in the periplasm. The transmembrane and periplasmic domains are separated by a 0.9-nm channel constriction composed of three stacked concentric phenylalanine, asparagine and tyrosine rings that may guide the extended polypeptide substrate through the secretion pore. The specificity factor CsgE forms a nonameric adaptor that binds and closes off the periplasmic face of the secretion channel, creating a 24,000 Å(3) pre-constriction chamber. Our structural, functional and electrophysiological analyses imply that CsgG is an ungated, non-selective protein secretion channel that is expected to employ a diffusion-based, entropy-driven transport mechanism.
| Type: | Article |
|---|---|
| Title: | Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1038/nature13768 |
| Publisher version: | http://dx.doi.org/10.1038/nature13768 |
| Language: | English |
| Additional information: | Copyright © 2014 Macmillan Publishers Limited. All rights reserved. |
| Keywords: | X-ray crystallography, Bacterial secretion, Lipoproteins, Nanopores |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1449023 |
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