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| {{STRUCTURE_2pvg| PDB=2pvg | SCENE= }} | | {{STRUCTURE_2pvg| PDB=2pvg | SCENE= }} |
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| '''Crystal srtucture of the binary complex between ferredoxin and ferredoxin:thioredoxin reductase'''
| | ===Crystal srtucture of the binary complex between ferredoxin and ferredoxin:thioredoxin reductase=== |
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| ==Overview==
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| Oxygen-evolving photosynthetic organisms regulate carbon metabolism through a light-dependent redox signalling pathway. Electrons are shuttled from photosystem I by means of ferredoxin (Fdx) to ferredoxin-thioredoxin reductase (FTR), which catalyses the two-electron-reduction of chloroplast thioredoxins (Trxs). These modify target enzyme activities by reduction, regulating carbon flow. FTR is unique in its use of a [4Fe-4S] cluster and a proximal disulphide bridge in the conversion of a light signal into a thiol signal. We determined the structures of FTR in both its one- and its two-electron-reduced intermediate states and of four complexes in the pathway, including the ternary Fdx-FTR-Trx complex. Here we show that, in the first complex (Fdx-FTR) of the pathway, the Fdx [2Fe-2S] cluster is positioned suitably for electron transfer to the FTR [4Fe-4S] centre. After the transfer of one electron, an intermediate is formed in which one sulphur atom of the FTR active site is free to attack a disulphide bridge in Trx and the other sulphur atom forms a fifth ligand for an iron atom in the FTR [4Fe-4S] centre--a unique structure in biology. Fdx then delivers a second electron that cleaves the FTR-Trx heterodisulphide bond, which occurs in the Fdx-FTR-Trx complex. In this structure, the redox centres of the three proteins are aligned to maximize the efficiency of electron transfer from the Fdx [2Fe-2S] cluster to the active-site disulphide of Trxs. These results provide a structural framework for understanding the mechanism of disulphide reduction by an iron-sulphur enzyme and describe previously unknown interaction networks for both Fdx and Trx (refs 4-6).
| | The line below this paragraph, {{ABSTRACT_PUBMED_17611542}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17611542 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17611542}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Iron-sulfur]] | | [[Category: Iron-sulfur]] |
| [[Category: Thioredoxin]] | | [[Category: Thioredoxin]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 13:52:10 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 12:03:13 2008'' |