2pvd
Crystal srtucture of the reduced ferredoxin:thioredoxin reductase
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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
2PVD is a Protein complex structure of sequences from 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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