4Y2N

Structure of CFA/I pili major subunit CfaB trimer


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.240 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Off-pathway assembly of fimbria subunits is prevented by chaperone CfaA of CFA/I fimbriae from enterotoxigenic E. coli.

Bao, R.Liu, Y.Savarino, S.J.Xia, D.

(2016) Mol Microbiol 102: 975-991

  • DOI: https://doi.org/10.1111/mmi.13530
  • Primary Citation of Related Structures:  
    4Y2L, 4Y2N, 4Y2O

  • PubMed Abstract: 

    The assembly of the class 5 colonization factor antigen I (CFA/I) fimbriae of enterotoxigenic E. coli was proposed to proceed via the alternate chaperone-usher pathway. Here, we show that in the absence of the chaperone CfaA, CfaB, the major pilin subunit of CFA/I fimbriae, is able to spontaneously refold and polymerize into cyclic trimers. CfaA kinetically traps CfaB to form a metastable complex that can be stabilized by mutations. Crystal structure of the stabilized complex reveals distinctive interactions provided by CfaA to trap CfaB in an assembly competent state through donor-strand complementation (DSC) and cleft-mediated anchorage. Mutagenesis indicated that DSC controls the stability of the chaperone-subunit complex and the cleft-mediated anchorage of the subunit C-terminus additionally assist in subunit refolding. Surprisingly, over-stabilization of the chaperone-subunit complex led to delayed fimbria assembly, whereas destabilizing the complex resulted in no fimbriation. Thus, CfaA acts predominantly as a kinetic trap by stabilizing subunit to avoid its off-pathway self-polymerization that results in energetically favorable trimers and could serve as a driving force for CFA/I pilus assembly, representing an energetic landscape unique to class 5 fimbria assembly.


  • Organizational Affiliation

    Division of Infectious Diseases, National Key Laboratory of Biotherapy/Collaborative Innovation Center of Biotherapy, West China Hospitals, Sichuan University, Chengdu, 610041, China.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CFA/I fimbrial subunit BA [auth B],
B [auth A],
C
153Escherichia coli ETEC H10407Mutation(s): 0 
Gene Names: cfaBETEC_p948_0400
UniProt
Find proteins for E3PPC4 (Escherichia coli O78:H11 (strain H10407 / ETEC))
Explore E3PPC4 
Go to UniProtKB:  E3PPC4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupE3PPC4
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.240 
  • Space Group: P 3 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 114.723α = 90
b = 114.723β = 90
c = 67.081γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHENIXphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-08-10
    Type: Initial release
  • Version 1.1: 2018-11-28
    Changes: Advisory, Data collection, Database references, Derived calculations
  • Version 1.2: 2023-09-27
    Changes: Advisory, Data collection, Database references, Refinement description