TY - JOUR
T1 - Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG
AU - Goyal, Parveen
AU - Krasteva, Petya V.
AU - Van Gerven, Nani
AU - Gubellini, Francesca
AU - Van Den Broeck, Imke
AU - Troupiotis-Tsaïlaki, Anastassia
AU - Jonckheere, Wim
AU - Péhau-Arnaudet, Gérard
AU - Pinkner, Jerome S.
AU - Chapman, Matthew R.
AU - Hultgren, Scott J.
AU - Howorka, Stefan
AU - Fronzes, Rémi
AU - Remaut, Han
N1 - Funding Information:
Acknowledgements This research was supported by VIB through project grant PRJ9 (P.G., N.V.G. and H.R.), by Hercules Foundation through equipment grant UABR/09/ 005, by National Institutes of Health RO1 grants AI099099 and AI048689 (J.P. and S.J.H.) and A1073847 (M.R.C.), and by Institut Pasteur and Centre national de la recherche scientifique (F.G., G.P.A. and R.F.). S.H. is funded by the Engineering and Physical Sciences Research Council (Institutional Sponsorship Award), the National Physical Laboratory and University College London Chemistry. F.G. is the recipient of a ‘Bourse Roux’ from Institut Pasteur. P.V.K. was supported by the European Research Council (ERC). We acknowledge Diamond Light Source for time on beamlines I02, I03, I04 and I24 under proposal mx7351, and the Soleil synchrotron for access to Proxima-1 and Proxima-2a under proposals 20100734, 20110924 and 20121253.
Publisher Copyright:
© 2014 Macmillan Publishers Limited.
PY - 2014/12/11
Y1 - 2014/12/11
N2 - 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 3 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 2-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.
AB - 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 3 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 2-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.
UR - http://www.scopus.com/inward/record.url?scp=84921858909&partnerID=8YFLogxK
U2 - 10.1038/nature13768
DO - 10.1038/nature13768
M3 - Article
C2 - 25219853
AN - SCOPUS:84921858909
VL - 516
SP - 250
EP - 253
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7530
ER -