Rieske protein
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| Identifiers | |||||||||
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| Symbol | Rieske | ||||||||
| Pfam | PF00355 | ||||||||
| InterPro | IPR005806 | ||||||||
| PROSITE | PDOC00177 | ||||||||
| SCOP | 1rie | ||||||||
| SUPERFAMILY | 1rie | ||||||||
| TCDB | 3.E.2 | ||||||||
| OPM protein | 1q90 | ||||||||
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| Available protein structures: | |
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| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
| Cytochrome B6-F complex Fe-S subunit, alpha helical transmembrane domain | |||||||||
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crystal structure of cytochrome b6f complex from m.laminosus
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| Identifiers | |||||||||
| Symbol | CytB6-F_Fe-S | ||||||||
| Pfam | PF08802 | ||||||||
| InterPro | IPR014909 | ||||||||
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| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
Rieske proteins are iron-sulfur protein (ISP) components of and which were first discovered and isolated by John S. Rieske and co-workers in 1964. It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues rather than two cysteine residues. They have since been found in plants, animals, and bacteria with widely ranging electron reduction potentials from -150 to +400 mV.
(also known as bc1 complex or complex III) is an enzyme complex of bacterial and mitochondrial oxidative phosphorylation systems. It catalyses the oxidation-reduction reaction of the mobile components ubiquinol and , contributing to an electrochemical potential difference across the mitochondrial inner or bacterial membrane, which is linked to ATP synthesis.
The complex consists of three subunits in most bacteria, and nine in mitochondria: both bacterial and mitochondrial complexes contain cytochrome b and cytochrome c1 subunits, and an iron-sulphur 'Rieske' subunit, which contains a high potential 2Fe-2S cluster. The mitochondrial form also includes six other subunits that do not possess redox centres. Plastoquinone-plastocyanin reductase (b6f complex), present in cyanobacteria and the chloroplasts of plants, catalyses the oxidoreduction of plastoquinol and cytochrome f. This complex, which is functionally similar to ubiquinol-cytochrome c reductase, comprises cytochrome b6, cytochrome f and Rieske subunits.
The Rieske subunit acts by binding either a ubiquinol or plastoquinol anion, transferring an electron to the 2Fe-2S cluster, then releasing the electron to the or haem iron. The reduction of the Rieske center increases the affinity of the subunit by several orders of magnitude, stabilizing the semiquinone radical at the Q(P) site. The Rieske domain has a [2Fe-2S] centre. Two conserved cysteines coordinate one Fe ion while the other Fe ion is coordinated by two conserved histidines. The 2Fe-2S cluster is bound in the highly conserved C-terminal region of the Rieske subunit.
The homologues of the Rieske proteins include ISP components of , aromatic-ring-hydroxylating dioxygenases (phthalate dioxygenase, benzene, naphthalene and toluene 1,2-dioxygenases) and arsenite oxidase (EC 1.20.98.1). Comparison of amino acid sequences has revealed the following consensus sequence:
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