2puk | pdb_00002puk
Crystal structure of the binary complex between ferredoxin: thioredoxin reductase and thioredoxin m
Structural highlights
Function[Q55389_SYNY3] FTR is a [4Fe-4S] protein playing a central role in the ferredoxin/thioredoxin regulatory chain. It converts an electron signal (photoreduced ferredoxin) to a thiol signal (reduced thioredoxin) in the regulation of enzymes by reduction of specific disulfide groups. Catalyzes the light-dependent activation of several photosynthetic enzymes (By similarity).[PIRNR:PIRNR000260] [TRXM_SPIOL] Participates in various redox reactions through the reversible oxidation of the active center dithiol to a disulfide. The M form is known to activate NADP-malate dehydrogenase. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedOxygen-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). 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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