1FQF

CRYSTAL STRUCTURES OF MUTANT (K296A) THAT ABOLISH THE DILYSINE INTERACTION IN THE N-LOBE OF HUMAN TRANSFERRIN

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.212 

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This is version 1.3 of the entry. See complete history. 

Literature

Crystal structures and iron release properties of mutants (K206A and K296A) that abolish the dilysine interaction in the N-lobe of human transferrin.

Nurizzo, D., Baker, H.M., He, Q.Y., MacGillivray, R.T., Mason, A.B., Woodworth, R.C., Baker, E.N.

(2001) Biochemistry 40: 1616-1623

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    • Human transferrin (Tf) is responsible for the binding and transport of iron in the bloodstream of vertebrates. Delivery of this bound iron to cells occurs by a process of receptor-mediated endocytosis during which Tf releases its iron at the reduced ...

    Human transferrin (Tf) is responsible for the binding and transport of iron in the bloodstream of vertebrates. Delivery of this bound iron to cells occurs by a process of receptor-mediated endocytosis during which Tf releases its iron at the reduced endosomal pH of approximately 5.6. Iron release from Tf involves a large conformational change in which the two domains that enclose the binding site in each lobe move apart. We have examined the role of two lysines, Lys206 and Lys296, that form a hydrogen-bonded pair close to the N-lobe binding site of human Tf and have been proposed to form a pH-sensitive trigger for iron release. We report high-resolution crystal structures for the K206A and K296A mutants of the N-lobe half-molecule of Tf, hTf/2N, and quantitative iron release data on these mutants and the double mutant K206A/K296A. The refined crystal structures (for K206A, R = 19.6% and R(free) = 23.7%; for K296A, R= 21.2% and R(free) = 29.5%) reveal a highly conserved hydrogen bonding network in the dilysine pair region that appears to be maintained even when individual hydrogen bonding groups change. The iron release data show that the mutants retain iron to a pH 1 unit lower than the pH limit of wild type hTf/2N, and release iron much more slowly as a result of the loss of the dilysine interaction. Added chloride ions are shown to accelerate iron release close to the pH at which iron is naturally lost and the closed structure becomes destabilized, and to retard it at higher pH.

    Organizational Affiliation: 

    School of Biological Sciences, University of Auckland, Auckland, New Zealand.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
SEROTRANSFERRIN
A
331Homo sapiensMutation(s): 1 
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
FE
Query on FE
Download SDF File 
Download CCD File 
A
FE (III) ION
Fe
VTLYFUHAOXGGBS-UHFFFAOYSA-N
 Ligand Interaction
CO3
Query on CO3
Download SDF File 
Download CCD File 
A
CARBONATE ION
C O3
BVKZGUZCCUSVTD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.212 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 44.000α = 90.00
b = 57.000β = 90.00
c = 132.900γ = 90.00
Software Package:
Software NamePurpose
CCP4data scaling
DENZOdata reduction
SCALAdata scaling
CNSphasing
CNSrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-05-16
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-02-01
    Type: Structure summary