1PNZ

Crystal structure of ferric citrate transporter FecA in the unliganded form


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.223 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA

Yue, W.W.Grizot, S.Buchanan, S.K.

(2003) J.Mol.Biol. 332: 353-368

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and comp ...

    Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and complexed with iron-free or diferric dicitrate. We show the structural mechanism for discrimination between the iron-free and ferric siderophore: the binding of diferric dicitrate, but not iron-free dicitrate alone, causes major conformational rearrangements in the transporter. The structure of FecA bound with iron-free dicitrate represents the first structure of a TonB-dependent transporter bound with an iron-free siderophore. Binding of diferric dicitrate to FecA results in changes in the orientation of the two citrate ions relative to each other and in their interactions with FecA, compared to the binding of iron-free dicitrate. The changes in ligand binding are accompanied by conformational changes in three areas of FecA: two extracellular loops, one plug domain loop and the periplasmic TonB-box motif. The positional and conformational changes in the siderophore and transporter initiate two independent events: ferric citrate transport into the periplasm and transcription induction of the fecABCDE transport genes. From these data, we propose a two-step ligand recognition event: FecA binds iron-free dicitrate in the non-productive state or first step, followed by siderophore displacement to form the transport-competent, diferric dicitrate-bound state in the second step.


    Organizational Affiliation

    National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Iron(III) dicitrate transport protein fecA precursor
A
751Escherichia coli (strain K12)Gene Names: fecA
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: BETA-BARREL
Sub Group: 
Beta-Barrel Membrane Proteins: Monomeric/Dimeric
Protein: 
FecA, siderophore transporter
Find proteins for P13036 (Escherichia coli (strain K12))
Go to UniProtKB:  P13036
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.223 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 117.050α = 90.00
b = 88.459β = 90.00
c = 95.300γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SCALEPACKdata scaling
HKL-2000data reduction
MOLREPphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-11-18
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance