Binding Site

2Fe-2S ferredoxin, iron-sulphur binding site (IPR006058)

Short name: 2Fe2S_fd_BS


Ferredoxins are iron-sulphur proteins that mediate electron transfer in a range of metabolic reactions [PMID: 1444257, PMID: 2506358]; they fall into several subgroups according to the nature of their iron-sulphur cluster(s). One group, originally found in chloroplast membranes, has been termed 'chloroplast-type' or 'plant-type', and includes ferredoxins from plants, algae, archaea, rhodobacter and a toluene degrading pseudomonas. Here, the active centre is a 2Fe-2S cluster, where the irons are tetrahedrally coordinated by both inorganic sulphurs and sulphurs provided by 4 conserved Cys residues [PMID: 1902376]. In chloroplasts, 2Fe-2S ferredoxins function as electron carriers in the photosynthetic electron transport chain and as electron donors to various cellular proteins. In hydroxylating bacterial dioxygenase systems, they serve as intermediate electron-transfer carriers between reductase flavoproteins and oxygenase [PMID: 1444257].

Several oxidoreductases contain redox domains similar to 2Fe-2S ferredoxins, including ferredoxin/ferredoxin reductase components of several bacterial aromatic di- and monooxygenases, phenol hydroxylase, methane monooxygenase, vanillate demethylase oxidoreductase, phthalate dioxygenase reductase, bacterial fumarate reductase iron-sulphur protein, eukaryotic succinate dehydrogenase and xanthine dehydrogenase. 3D structures are known for a number of 2Fe-2S ferredoxins [PMID: 1902376] and for the ferredoxin reductase/ferredoxin fusion protein phthalate dioxygenase reductase [PMID: 1280857]. The fold belongs to the alpha + beta class, with 3 helices and 4 strands forming a barrel-like structure, and an extruded loop containing 3 of the 4 cysteinyl residues of the iron-sulphur cluster.

In the 2Fe-2S ferredoxins, four cysteine residues bind the iron-sulphur cluster. Three of these cysteines are clustered together in the same region of the protein. This sequence cover the three cysteine residues involved in iron-sulphur binding.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0051537 2 iron, 2 sulfur cluster binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns