1fqe
From Proteopedia
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|PDB= 1fqe |SIZE=350|CAPTION= <scene name='initialview01'>1fqe</scene>, resolution 1.8Å | |PDB= 1fqe |SIZE=350|CAPTION= <scene name='initialview01'>1fqe</scene>, resolution 1.8Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand= | + | |LIGAND= <scene name='pdbligand=CO3:CARBONATE+ION'>CO3</scene>, <scene name='pdbligand=FE:FE+(III)+ION'>FE</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene> |
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY=[[1fqf|1FQF]], [[1a8e|1A8E]] | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1fqe FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1fqe OCA], [http://www.ebi.ac.uk/pdbsum/1fqe PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1fqe RCSB]</span> | ||
}} | }} | ||
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==Overview== | ==Overview== | ||
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. | 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. | ||
| - | |||
| - | ==Disease== | ||
| - | Known diseases associated with this structure: Atransferrinemia OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=190000 190000]], Iron deficiency anemia, susceptibility to OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=190000 190000]] | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Baker, H M.]] | [[Category: Baker, H M.]] | ||
[[Category: Nurizzo, D.]] | [[Category: Nurizzo, D.]] | ||
| - | [[Category: CO3]] | ||
| - | [[Category: FE]] | ||
| - | [[Category: K]] | ||
[[Category: dilysine interaction]] | [[Category: dilysine interaction]] | ||
[[Category: iron transport]] | [[Category: iron transport]] | ||
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[[Category: transferrin]] | [[Category: transferrin]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 20:28:14 2008'' |
Revision as of 17:28, 30 March 2008
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| , resolution 1.8Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , , | ||||||
| Related: | 1FQF, 1A8E
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
CRYSTAL STRUCTURES OF MUTANT (K206A) THAT ABOLISH THE DILYSINE INTERACTION IN THE N-LOBE OF HUMAN TRANSFERRIN
Overview
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.
About this Structure
1FQE is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
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 HM, He QY, MacGillivray RT, Mason AB, Woodworth RC, Baker EN, Biochemistry. 2001 Feb 13;40(6):1616-23. PMID:11327820
Page seeded by OCA on Sun Mar 30 20:28:14 2008
