1po0
From Proteopedia
(New page: 200px<br /><applet load="1po0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1po0, resolution 2.15Å" /> '''Crystal structure of...) |
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| - | [[Image:1po0.jpg|left|200px]]<br /><applet load="1po0" size=" | + | [[Image:1po0.jpg|left|200px]]<br /><applet load="1po0" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1po0, resolution 2.15Å" /> | caption="1po0, resolution 2.15Å" /> | ||
'''Crystal structure of ferric citrate transporter FecA in complex with iron-free citrate'''<br /> | '''Crystal structure of ferric citrate transporter FecA in complex with iron-free citrate'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Escherichia coli possesses a TonB-dependent transport system, which | + | Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and complexed with iron-free or diferric dicitrate. We show the structural mechanism for discrimination between the iron-free and ferric siderophore: the binding of diferric dicitrate, but not iron-free dicitrate alone, causes major conformational rearrangements in the transporter. The structure of FecA bound with iron-free dicitrate represents the first structure of a TonB-dependent transporter bound with an iron-free siderophore. Binding of diferric dicitrate to FecA results in changes in the orientation of the two citrate ions relative to each other and in their interactions with FecA, compared to the binding of iron-free dicitrate. The changes in ligand binding are accompanied by conformational changes in three areas of FecA: two extracellular loops, one plug domain loop and the periplasmic TonB-box motif. The positional and conformational changes in the siderophore and transporter initiate two independent events: ferric citrate transport into the periplasm and transcription induction of the fecABCDE transport genes. From these data, we propose a two-step ligand recognition event: FecA binds iron-free dicitrate in the non-productive state or first step, followed by siderophore displacement to form the transport-competent, diferric dicitrate-bound state in the second step. |
==About this Structure== | ==About this Structure== | ||
| - | 1PO0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with FLC as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1PO0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=FLC:'>FLC</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PO0 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Buchanan, S | + | [[Category: Buchanan, S K.]] |
[[Category: Grizot, S.]] | [[Category: Grizot, S.]] | ||
| - | [[Category: Yue, W | + | [[Category: Yue, W W.]] |
[[Category: FLC]] | [[Category: FLC]] | ||
[[Category: beta barrel]] | [[Category: beta barrel]] | ||
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[[Category: tonb-dependent transport]] | [[Category: tonb-dependent transport]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:30:40 2008'' |
Revision as of 12:30, 21 February 2008
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Crystal structure of ferric citrate transporter FecA in complex with iron-free citrate
Overview
Escherichia coli possesses a TonB-dependent transport system, which exploits the iron-binding capacity of citrate and its natural abundance. Here, we describe three structures of the outer membrane ferric citrate transporter FecA: unliganded and complexed with iron-free or diferric dicitrate. We show the structural mechanism for discrimination between the iron-free and ferric siderophore: the binding of diferric dicitrate, but not iron-free dicitrate alone, causes major conformational rearrangements in the transporter. The structure of FecA bound with iron-free dicitrate represents the first structure of a TonB-dependent transporter bound with an iron-free siderophore. Binding of diferric dicitrate to FecA results in changes in the orientation of the two citrate ions relative to each other and in their interactions with FecA, compared to the binding of iron-free dicitrate. The changes in ligand binding are accompanied by conformational changes in three areas of FecA: two extracellular loops, one plug domain loop and the periplasmic TonB-box motif. The positional and conformational changes in the siderophore and transporter initiate two independent events: ferric citrate transport into the periplasm and transcription induction of the fecABCDE transport genes. From these data, we propose a two-step ligand recognition event: FecA binds iron-free dicitrate in the non-productive state or first step, followed by siderophore displacement to form the transport-competent, diferric dicitrate-bound state in the second step.
About this Structure
1PO0 is a Single protein structure of sequence from Escherichia coli with as ligand. Full crystallographic information is available from OCA.
Reference
Structural evidence for iron-free citrate and ferric citrate binding to the TonB-dependent outer membrane transporter FecA., Yue WW, Grizot S, Buchanan SK, J Mol Biol. 2003 Sep 12;332(2):353-68. PMID:12948487
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