Crystal Structure of Human Serum Transferrin, N-Lobe L66W mutant

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.196 

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The Position of Arginine 124 Controls the Rate of Iron Release from the N-lobe of Human Serum Transferrin. A Structural Study

Adams, T.E.Mason, A.B.He, Q.Y.Halbrooks, P.J.Briggs, S.K.Smith, V.C.MacGillivray, R.T.Everse, S.J.

(2003) J Biol Chem 278: 6027-6033

  • DOI: https://doi.org/10.1074/jbc.M210349200
  • Primary Citation of Related Structures:  
    1N7W, 1N7X, 1N84

  • PubMed Abstract: 

    Human serum transferrin (hTF) is a bilobal iron-binding and transport protein that carries iron in the blood stream for delivery to cells by a pH-dependent mechanism. Two iron atoms are held tightly in two deep clefts by coordination to four amino acid residues in each cleft (two tyrosines, a histidine, and an aspartic acid) and two oxygen atoms from the "synergistic" carbonate anion. Other residues in the binding pocket, not directly coordinated to iron, also play critical roles in iron uptake and release through hydrogen bonding to the liganding residues. The original crystal structures of the iron-loaded N-lobe of hTF (pH 5.75 and 6.2) revealed that the synergistic carbonate is stabilized by interaction with Arg-124 and that both the arginine and the carbonate adopt two conformations (MacGillivray, R. T. A., Moore, S. A., Chen, J., Anderson, B. F., Baker, H., Luo, Y. G., Bewley, M., Smith, C. A., Murphy, M. E., Wang, Y., Mason, A. B., Woodworth, R. C., Brayer, G. D., and Baker, E. N. (1998) Biochemistry 37, 7919-7928). In the present study, we show that the two conformations are also found for a structure at pH 7.7, indicating that this finding was not strictly a function of pH. We also provide structures for two single point mutants (Y45E and L66W) designed to force Arg-124 to adopt each of the previously observed conformations. The structures of each mutant show that this goal was accomplished, and functional studies confirm the hypothesis that access to the synergistic anion dictates the rate of iron release. These studies highlight the importance of the arginine/carbonate movement in the mechanism of iron release in the N-lobe of hTF. Access to the carbonate via a water channel allows entry of protons and anions, enabling the attack on the iron.

  • Organizational Affiliation

    Department of Biochemistry, University of Vermont, College of Medicine, Burlington, Vermont 05405, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Serotransferrin331Homo sapiensMutation(s): 1 
Gene Names: TF
UniProt & NIH Common Fund Data Resources
Find proteins for P02787 (Homo sapiens)
Explore P02787 
Go to UniProtKB:  P02787
GTEx:  ENSG00000091513 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02787
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.196 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 45.183α = 90
b = 57.916β = 90
c = 135.513γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-03-18
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2014-04-16
    Changes: Data collection
  • Version 1.4: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.5: 2023-08-16
    Changes: Data collection, Refinement description