1RYO

Human serum transferrin, N-lobe bound with oxalate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.2 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.221 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The oxalate effect on release of iron from human serum transferrin explained.

Halbrooks, P.J.Mason, A.B.Adams, T.E.Briggs, S.K.Everse, S.J.

(2004) J.Mol.Biol. 339: 217-226

  • DOI: 10.1016/j.jmb.2004.03.049

  • PubMed Abstract: 
  • A unique feature of the mechanism of iron binding to the transferrin (TF) family is the synergistic relationship between metal binding and anion binding. Little or no iron will bind to the protein without concomitant binding of an anion, physiologica ...

    A unique feature of the mechanism of iron binding to the transferrin (TF) family is the synergistic relationship between metal binding and anion binding. Little or no iron will bind to the protein without concomitant binding of an anion, physiologically identified as carbonate. Substitution of oxalate for carbonate produces no significant changes in polypeptide folding or domain orientation in the N-lobe of human serum TF (hTF) as revealed by our 1.2A structure. The oxalate is able to bind to the iron in a symmetric bidentate fashion, which, combined with the low pK(a) of the oxalate anion, makes iron displacement more difficult as documented by both iron release kinetic and equilibrium data. Characterization of an N-lobe in which the arginine at position 124 is mutated to alanine reveals that the stabilizing effect of oxalate is even greater in this mutant and nearly cancels the destabilizing effect of the mutation. Importantly, incorporation of oxalate as the synergistic anion appears to completely inhibit removal of iron from recombinant full-length hTF by HeLa S(3) cells, strongly indicating that oxalate also replaces carbonate in the C-lobe to form a stable complex. Kinetic studies confirm this claim. The combination of structural and functional data provides a coherent delineation of the effect of oxalate binding on hTF and rationalizes the results of many previous studies. In the context of iron uptake by cells, substitution of carbonate by oxalate effectively locks the iron into each lobe of hTF, thereby interfering with normal iron metabolism.


    Organizational Affiliation

    Department of Biochemistry, College of Medicine, University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Serotransferrin
A
327Homo sapiensMutation(s): 0 
Gene Names: TF
Find proteins for P02787 (Homo sapiens)
Go to Gene View: TF
Go to UniProtKB:  P02787
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
OXL
Query on OXL

Download SDF File 
Download CCD File 
A
OXALATE ION
C2 O4
MUBZPKHOEPUJKR-UHFFFAOYSA-L
 Ligand Interaction
FE
Query on FE

Download SDF File 
Download CCD File 
A
FE (III) ION
Fe
VTLYFUHAOXGGBS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.2 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.221 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 44.092α = 90.00
b = 57.252β = 90.00
c = 135.988γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
SCALEPACKdata scaling
CNSrefinement
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-05-11
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance