Structure of a HG-derivative CsgG

Experimental Data Snapshot

  • Resolution: 3.10 Å
  • R-Value Free: 0.278 
  • R-Value Work: 0.236 
  • R-Value Observed: 0.238 

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Structure of the nonameric bacterial amyloid secretion channel

Cao, B.Zhao, Y.Kou, Y.Ni, D.Zhang, X.C.Huang, Y.

(2014) Proc Natl Acad Sci U S A 111: E5439-E5444

  • DOI: https://doi.org/10.1073/pnas.1411942111
  • Primary Citation of Related Structures:  
    3X2R, 4Q79

  • PubMed Abstract: 

    Various strains of bacteria are able to produce a unique class of functional amyloids termed curli, which are critical for biofilm formation, host cell adhesion, and colonization of inert surfaces. Curli are secreted via the type VIII bacterial secretion system, and they share biochemical and structural characteristics with amyloid fibers that have been implicated in deleterious disease in humans. Here, we report the crystal structure of Escherichia coli CsgG, which is an essential lipoprotein component of the type VIII secretion system and which forms a secretion channel in the bacterial outer membrane for transporting curli subunits. CsgG forms a crown-shaped, symmetric nonameric channel that spans the outer membrane via a 36-strand β-barrel, with each subunit contributing four β-strands. This nonameric complex contains a central channel with a pore located at the middle. The eyelet of the pore is ∼12 Å in diameter and is lined with three stacked nine-residue rings consisting of Tyr-66, Asn-70, or Phe-71. Our structure-based functional studies suggest that Tyr-66 and Phe-71 residues function as gatekeepers for the selective secretion of curli subunits. Our study describes in detail, to our knowledge, the first core structure of the type VIII bacterial secretion machinery. Importantly, our structural analysis suggests that the curli subunits are secreted via CsgG across the bacterial outer membrane in an unfolded form.

  • Organizational Affiliation

    National Laboratory of Biomacromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China;

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CsgG277Escherichia coli Xuzhou21Mutation(s): 0 
Gene Names: CDCO157_1350
Membrane Entity: Yes 
Find proteins for A0A0F6C2F5 (Escherichia coli Xuzhou21)
Explore A0A0F6C2F5 
Go to UniProtKB:  A0A0F6C2F5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A0F6C2F5
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.10 Å
  • R-Value Free: 0.278 
  • R-Value Work: 0.236 
  • R-Value Observed: 0.238 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 171.64α = 90
b = 176.88β = 90
c = 104.99γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-12-17
    Type: Initial release
  • Version 1.1: 2015-04-08
    Changes: Database references
  • Version 1.2: 2024-03-20
    Changes: Data collection, Database references, Derived calculations