Rieske proteins are iron–sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes and are responsible for electron transfer in some biological systems. John S. Rieske and co-workers first discovered the protein and in 1964 isolated an acetylated form of the bovine Mitochondrion.
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.
Biological function
Ubiquinol-cytochrome-c reductase (also known as bc1 complex or complex III) is an
enzyme complex of bacterial and mitochondrial oxidative phosphorylation systems. It catalyses the
Redox of the mobile components
ubiquinol and
cytochrome c, contributing to an electrochemical potential difference across the mitochondrial inner or
Cell membrane, which is linked to
ATP synthase.
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–sulfur 'Rieske' subunit, which contains a high potential 2Fe-2S cluster.
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 cytochrome c or cytochrome f Heme.
Rieske protein family
The homologues of the
Rieske proteins include ISP components of cytochrome
b6 f complex, 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:
- Cys-Xaa-His-(Xaa)15–17-Cys-Xaa-Xaa-His
3D structure
The overall fold of Rieske proteins, comprising two subdomains, is dominated by antiparallel β-structure and contains variable numbers of
Alpha helix. The smaller "cluster-binding" subdomains in mitochondrial and chloroplast proteins are virtually identical, whereas the large subdomains are substantially different in spite of a common folding topology. The Fe
2S
2 cluster-binding subdomains have the topology of an incomplete antiparallel β-barrel. One iron atom of the Rieske Fe
2S
2 cluster in the domain is coordinated by two
cysteine residues and the other is coordinated by two
histidine residues through the N
δ atoms. The ligands coordinating the cluster originate from two loops; each loop contributes one Cys and one His.
Subfamilies
-
Rieske iron–sulfur protein, C-terminal
-
Arsenite oxidase, small subunit
Human proteins containing this domain
AIFM3;
RFESD; UQCRFS1;
Further reading
External links
-
- X-ray structure of Rieske protein (water-soluble fragment) of the bovine mitochondrial cytochrome bc1 complex
-
- X-ray structure of Rieske protein (water-soluble fragment) of the spinach chloroplast cytochrome b6 fcomplex
-
- X-ray structure of Rieske-type ferredoxin associated with biphenyl dioxygenase from Burkholderia cepacia
-
- X-ray structure of Rieske subunit of arsenite oxidase from Alcaligenes faecalis
-
- X-ray structure of the Sphingomonas yanoikuyae B1 Rieske ferredoxin
-
- X-ray structure of the Pseudomonas Naphthalene 1,2-dioxygenase Rieske ferredoxin
-
- InterPro entry for Rieske 2Fe-2S region
