2pu9: Difference between revisions

Revision as of 19:33, 21 February 2008

Crystal srtucture of the binary complex between ferredoxin: thioredoxin reductase and thioredoxin f

OverviewOverview

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).

About this StructureAbout this Structure

2PU9 is a Protein complex structure of sequences from Spinacia oleracea and Synechocystis sp. with and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Structural snapshots along the reaction pathway of ferredoxin-thioredoxin reductase., Dai S, Friemann R, Glauser DA, Bourquin F, Manieri W, Schurmann P, Eklund H, Nature. 2007 Jul 5;448(7149):92-6. PMID:17611542

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 ==Overview==
-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).
+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).
 ==About this Structure==
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 [[Category: thioredoxin]]
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