1n7x
From Proteopedia
(New page: 200px<br /> <applet load="1n7x" size="450" color="white" frame="true" align="right" spinBox="true" caption="1n7x, resolution 2.10Å" /> '''HUMAN SERUM TRANSFE...) |
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| - | [[Image:1n7x.gif|left|200px]]<br /> | + | [[Image:1n7x.gif|left|200px]]<br /><applet load="1n7x" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1n7x" size=" | + | |
caption="1n7x, resolution 2.10Å" /> | caption="1n7x, resolution 2.10Å" /> | ||
'''HUMAN SERUM TRANSFERRIN, N-LOBE Y45E MUTANT'''<br /> | '''HUMAN SERUM TRANSFERRIN, N-LOBE Y45E MUTANT'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Human serum transferrin (hTF) is a bilobal iron-binding and transport | + | 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. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1N7X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with CO3 and FE as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1N7X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=CO3:'>CO3</scene> and <scene name='pdbligand=FE:'>FE</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N7X OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Adams, T | + | [[Category: Adams, T E.]] |
| - | [[Category: Briggs, S | + | [[Category: Briggs, S K.]] |
| - | [[Category: Everse, S | + | [[Category: Everse, S J.]] |
| - | [[Category: Halbrooks, P | + | [[Category: Halbrooks, P J.]] |
| - | [[Category: He, Q | + | [[Category: He, Q Y.]] |
| - | [[Category: Macgillivray, R | + | [[Category: Macgillivray, R T.]] |
| - | [[Category: Mason, A | + | [[Category: Mason, A B.]] |
| - | [[Category: Smith, V | + | [[Category: Smith, V C.]] |
[[Category: CO3]] | [[Category: CO3]] | ||
[[Category: FE]] | [[Category: FE]] | ||
[[Category: iron transport]] | [[Category: iron transport]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:03:12 2008'' |
Revision as of 12:03, 21 February 2008
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HUMAN SERUM TRANSFERRIN, N-LOBE Y45E MUTANT
Contents |
Overview
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.
Disease
Known diseases associated with this structure: Atransferrinemia OMIM:[190000], Iron deficiency anemia, susceptibility to OMIM:[190000]
About this Structure
1N7X is a Single protein structure of sequence from Homo sapiens with and as ligands. Full crystallographic information is available from OCA.
Reference
The position of arginine 124 controls the rate of iron release from the N-lobe of human serum transferrin. A structural study., Adams TE, Mason AB, He QY, Halbrooks PJ, Briggs SK, Smith VC, MacGillivray RT, Everse SJ, J Biol Chem. 2003 Feb 21;278(8):6027-33. Epub 2002 Nov 27. PMID:12458193
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