Rieske protein

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 and isolated the proteins in 1964.[1] 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.[2]

Rieske protein from cytochrome b6f complex. (PDB: 1vf5​)
Identifiers
SymbolRieske
PfamPF00355
InterProIPR005806
PROSITEPDOC00177
SCOPe1rie / SUPFAM
TCDB3.E.2
OPM superfamily92
OPM protein1q90
CDDcd03467
Cytochrome B6-F complex Fe-S subunit, alpha helical transmembrane domain
crystal structure of cytochrome b6f complex from m.laminosus
Identifiers
SymbolCytB6-F_Fe-S
PfamPF08802
InterProIPR014909

Biological function (in oxidative phosphorylation systems)

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 oxidation-reduction reaction of the mobile components ubiquinol and cytochrome c, contributing to an electrochemical potential difference across the mitochondrial inner or bacterial membrane, which is linked to ATP synthesis.[3][4]

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.[5] 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.[6]

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 iron.[3][6] 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.[7] The Rieske domain has a [2Fe-2S] center. 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.

Rieske protein family

The homologues of the Rieske proteins include ISP components of cytochrome b6f 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
Rieske iron–sulfur center

3D structure

The crystal structures of a number of Rieske proteins are known. The overall fold, comprising two subdomains, is dominated by antiparallel β-structure and contains variable numbers of α-helices. 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 [Fe2S2] cluster-binding subdomains have the topology of an incomplete antiparallel β-barrel. One iron atom of the Rieske [Fe2S2] cluster in the domain is coordinated by two cysteine residues and the other is coordinated by two histidine residues through the Nδ atoms. The ligands coordinating the cluster originate from two loops; each loop contributes one Cys and one His.

Subfamilies

Human proteins containing this domain

AIFM3; RFESD; UQCRFS1;

gollark: I find it suspicious that TWO of them include the word "functor".
gollark: No, I meant #8 but cannot count.
gollark: ... is it using *typing overloads* to do *pattern matching*?
gollark: I checked.
gollark: #5 has a rickroll in it.

References
  1. Rieske JS, Maclennan DH, Coleman, R (1964). "Isolation and properties of an iron-protein from the (reduced coenzyme Q)-cytochrome C reductase complex of the respiratory chain". Biochem. Biophys. Res. Commun. 15 (4): 338–344. doi:10.1016/0006-291X(64)90171-8.CS1 maint: multiple names: authors list (link)
  2. Brown, E.N. and Friemann, R. and Karlsson, A. and Parales, J.V. and Couture, M.M. and Eltis, L.D. and Ramaswamy, S. (2008). "Determining Rieske cluster reduction potentials". J. Biol. Inorg. Chem. 13 (8): 1301–1313. doi:10.1007/s00775-008-0413-4. PMID 18719951.CS1 maint: multiple names: authors list (link)
  3. Harnisch U, Weiss H, Sebald W (May 1985). "The primary structure of the iron-sulfur subunit of ubiquinol-cytochrome c reductase from Neurospora, determined by cDNA and gene sequencing". Eur. J. Biochem. 149 (1): 95–9. doi:10.1111/j.1432-1033.1985.tb08898.x. PMID 2986972.
  4. Gabellini N, Sebald W (February 1986). "Nucleotide sequence and transcription of the fbc operon from Rhodopseudomonas sphaeroides. Evaluation of the deduced amino acid sequences of the FeS protein, cytochrome b and cytochrome c1". Eur. J. Biochem. 154 (3): 569–79. doi:10.1111/j.1432-1033.1986.tb09437.x. PMID 3004982.
  5. Kurowski B, Ludwig B (October 1987). "The genes of the Paracoccus denitrificans bc1 complex. Nucleotide sequence and homologies between bacterial and mitochondrial subunits". J. Biol. Chem. 262 (28): 13805–11. PMID 2820981.
  6. Madueño F, Napier JA, Cejudo FJ, Gray JC (October 1992). "Import and processing of the precursor of the Rieske FeS protein of tobacco chloroplasts". Plant Mol. Biol. 20 (2): 289–99. doi:10.1007/BF00014496. PMID 1391772.
  7. Link TA (July 1997). "The role of the 'Rieske' iron sulfur protein in the hydroquinone oxidation (Q(P)) site of the cytochrome bc1 complex. The 'proton-gated affinity change' mechanism". FEBS Lett. 412 (2): 257–64. doi:10.1016/S0014-5793(97)00772-2. PMID 9256231.

Further reading
  • PDB: 1RIE​ - X-ray structure of Rieske protein (water-soluble fragment) of the bovine mitochondrial cytochrome bc1 complex
  • PDB: 1RFS​ - X-ray structure of Rieske protein (water-soluble fragment) of the spinach chloroplast cytochrome b6 fcomplex
  • PDB: 1FQT​ - X-ray structure of Rieske-type ferredoxin associated with biphenyl dioxygenase from Burkholderia cepacia
  • PDB: 1G8J​ - X-ray structure of Rieske subunit of arsenite oxidase from Alcaligenes faecalis
  • PDB: 2I7F​ - X-ray structure of the Sphingomonas yanoikuyae B1 Rieske ferredoxin
  • PDB: 2QPZ​ - X-ray structure of the Pseudomonas Naphthalene 1,2-dioxygenase Rieske ferredoxin
  • InterPro: IPR005806 - InterPro entry for Rieske [2Fe-2S] region
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