1HSE

H253M N TERMINAL LOBE OF HUMAN LACTOFERRIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Work: 0.178 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Mutagenesis of the histidine ligand in human lactoferrin: iron binding properties and crystal structure of the histidine-253-->methionine mutant.

Nicholson, H.Anderson, B.F.Bland, T.Shewry, S.C.Tweedie, J.W.Baker, E.N.

(1997) Biochemistry 36: 341-346

  • DOI: 10.1021/bi961908y

  • PubMed Abstract: 
  • The contribution of the conserved His ligand to iron binding in transferrins has been addressed by site-directed mutagenesis and X-ray crystallographic analysis. His 253 in the N-terminal half-molecule of human lactoferrin, LfN (residues 1-333), has ...

    The contribution of the conserved His ligand to iron binding in transferrins has been addressed by site-directed mutagenesis and X-ray crystallographic analysis. His 253 in the N-terminal half-molecule of human lactoferrin, LfN (residues 1-333), has been changed to Gly, Ala, Pro, Thr, Leu, Phe, Met, Tyr, Glu, Gln, and Cys by oligonucleotide-directed mutagenesis. The proteins have been expressed in baby hamster kidney cells, at high levels, and purified. The results show that the His ligand is essential for the stability of the iron binding site. All of the substitutions destabilized iron binding irrespective of whether the replacements were potential iron ligands or not. Iron was lost below pH approximately 6 for the Cys, Glu, and Tyr mutants and below pH 7 or higher for the others, compared with pH 5.0 for LfN. The destabilization is attributed to both steric and electronic effects. The importance of electronic effects has been shown by the crystal structure of the H253M mutant, which has been determined at an effective resolution of 2.5 A and refined to a final R factor of 0.173. The iron atom is changed from six-coordinate to five-coordinate; the Met 253 side chain is not bound to iron even though there appears to be no steric barrier. This is attributed to the poorer affinity of the thioether ligand for Fe(III) compared with imidazole nitrogen. The decreased stability of the iron binding is attributed solely to the loss of the His ligand as the protein conformation and interdomain interactions are unchanged.


    Related Citations: 
    • Studies of the N-Terminal Half of Human Lactoferrin Produced from the Cloned Cdna Demonstrate that Interlobe Interactions Modulate Iron Release
      Day, C.L.,Stowell, K.M.,Baker, E.N.,Tweedie, J.W.
      (1992) J.Biol.Chem. 267: 13857
    • Structure of the Recombinant N-Terminal Lobe of Human Lactoferrin at 2.0 A Resolution
      Day, C.L.,Anderson, B.F.,Tweedie, J.W.,Baker, E.N.
      (1993) J.Mol.Biol. 232: 1084


    Organizational Affiliation

    Department of Biochemistry, Massey University, Palmerston North, New Zealand.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
LACTOFERRIN
A
334Homo sapiensGene Names: LTF (GIG12, LF)
EC: 3.4.21.-
Find proteins for P02788 (Homo sapiens)
Go to Gene View: LTF
Go to UniProtKB:  P02788
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: 2.2 Å
  • R-Value Work: 0.178 
  • Space Group: P 41 21 2
Unit Cell:
Length (Å)Angle (°)
a = 58.400α = 90.00
b = 58.400β = 90.00
c = 217.900γ = 90.00
Software Package:
Software NamePurpose
RIGAKUdata collection
TNTrefinement
RIGAKUdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-03-12
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance