2PUK

Crystal structure of the binary complex between ferredoxin: thioredoxin reductase and thioredoxin m

Summary for 2PUK

• Entry DOI: 10.2210/pdb2puk/pdb
• Related: 2PU9
• Descriptor: Ferredoxin-thioredoxin reductase, catalytic chain, Ferredoxin-thioredoxin reductase, variable chain, Thioredoxin M-type, chloroplast (TRX-M), ... (4 entities in total)
• Functional Keywords: thioredoxin, protein-protein complex, redox, iron-sulfur, electron transport
• Biological source: Synechocystis sp.; More
• Cellular location: Plastid, chloroplast: P07591
• Total number of polymer chains: 6
• Total formula weight: 65991.51

Authors

Dai, S.,Friemann, R.,Schurmann, P.,Eklund, H. (deposition date: 2007-05-09, release date: 2007-07-10, Last modification date: 2024-11-13)

Primary citation

Dai, S.,Friemann, R.,Glauser, D.A.,Bourquin, F.,Manieri, W.,Schurmann, P.,Eklund, H.
Structural snapshots along the reaction pathway of ferredoxin-thioredoxin reductase.
Nature, 448:92-96, 2007

PubMed Abstract: 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).

PubMed: 17611542
DOI: 10.1038/nature05937

Experimental method

X-RAY DIFFRACTION (3 Å)