The Crystal Structure of FhuE from E. coli in complex with its substrate Coprogen

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.208 

Starting Model: experimental
View more details

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.3 of the entry. See complete history


Determination of the molecular basis for coprogen import by Gram-negative bacteria.

Grinter, R.Lithgow, T.

(2019) IUCrJ 6: 401-411

  • DOI: https://doi.org/10.1107/S2052252519002926
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    In order to survive in mixed microbial communities, some species of fungi secrete coprogens, siderophores that facilitate capture of the scarce nutrient iron. The TonB-dependent transporter FhuE is integrated in the outer membrane of Gram-negative bacteria and has been reported to scavenge these fungally produced coprogens. In this work, an Escherichia coli strain was engineered that is dependent solely on FhuE for its access to siderophore-sequestered iron. Using this tool, it is shown that while FhuE is highly active in the import of coprogens, it has some level of promiscuity, acting as a low-affinity transporter for related siderophores. The crystal structure of FhuE in complex with coprogen was determined, providing a structural basis to explain this selective promiscuity. The structural data, in combination with functional analysis, presented in this work show that FhuE has evolved to specifically engage with planar siderophores. A potential evolutionary driver, and a critical consequence of this selectivity, is that it allows FhuE to exclude antibiotics that mimic nonplanar hydroxamate siderophores: these toxic molecules could otherwise cross the outer membrane barrier through a Trojan horse mechanism.

  • Organizational Affiliation

    Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Monash, Victoria 3800, Australia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
FhuE receptor693Escherichia coli BW25113Mutation(s): 0 
Gene Names: fhuEb1102JW1088
Membrane Entity: Yes 
Find proteins for P16869 (Escherichia coli (strain K12))
Explore P16869 
Go to UniProtKB:  P16869
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP16869
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.208 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.19α = 90
b = 103.86β = 90
c = 118.62γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Wellcome TrustUnited Kingdom106077/Z/14/Z

Revision History  (Full details and data files)

  • Version 1.0: 2019-04-10
    Type: Initial release
  • Version 1.1: 2019-05-29
    Changes: Data collection, Database references
  • Version 1.2: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Derived calculations, Refinement description, Structure summary
  • Version 1.3: 2023-10-11
    Changes: Data collection, Database references, Refinement description, Structure summary