Crystal Structure of CofB from Enterotoxigenic Escherichia coli

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.205 
  • R-Value Observed: 0.206 

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Crystal Structure of the Minor Pilin CofB, the Initiator of CFA/III Pilus Assembly in Enterotoxigenic Escherichia coli.

Kolappan, S.Ng, D.Yang, G.Harn, T.Craig, L.

(2015) J Biol Chem 290: 25805-25818

  • DOI: https://doi.org/10.1074/jbc.M115.676106
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Type IV pili are extracellular polymers of the major pilin subunit. These subunits are held together in the pilus filament by hydrophobic interactions among their N-terminal α-helices, which also anchor the pilin subunits in the inner membrane prior to pilus assembly. Type IV pilus assembly involves a conserved group of proteins that span the envelope of Gram-negative bacteria. Among these is a set of minor pilins, so named because they share their hydrophobic N-terminal polymerization/membrane anchor segment with the major pilins but are much less abundant. Minor pilins influence pilus assembly and retraction, but their precise functions are not well defined. The Type IV pilus systems of enterotoxigenic Escherichia coli and Vibrio cholerae are among the simplest of Type IV pilus systems and possess only a single minor pilin. Here we show that the enterotoxigenic E. coli minor pilins CofB and LngB are required for assembly of their respective Type IV pili, CFA/III and Longus. Low levels of the minor pilins are optimal for pilus assembly, and CofB can be detected in the pilus fraction. We solved the 2.0 Å crystal structure of N-terminally truncated CofB, revealing a pilin-like protein with an extended C-terminal region composed of two discrete domains connected by flexible linkers. The C-terminal region is required for CofB to initiate pilus assembly. We propose a model for CofB-initiated pilus assembly with implications for understanding filament growth in more complex Type IV pilus systems as well as the related Type II secretion system.

  • Organizational Affiliation

    From the Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CofB498Escherichia coliMutation(s): 0 
Gene Names: cofB
Find proteins for Q93I73 (Escherichia coli)
Explore Q93I73 
Go to UniProtKB:  Q93I73
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ93I73
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.205 
  • R-Value Observed: 0.206 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 104.895α = 90
b = 104.895β = 90
c = 362.288γ = 120
Software Package:
Software NamePurpose
Blu-Icedata collection
XDSdata reduction
Aimlessdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-06-03
    Type: Initial release
  • Version 1.1: 2015-11-11
    Changes: Database references