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 mitochondrial protein.[1] In 1979, Trumpower's team isolated the "oxidation factor" from bovine mitochondria and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein [2] 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.[3]
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.[6] The mitochondrial form also includes six other subunits that do not possess redox centres. Plastoquinone-plastocyaninreductase (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.[7]
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 fheme iron.[4][7] The reduction of the Rieske center increases the affinity of the subunit by several orders of magnitude, stabilizing the semiquinoneradical at the Q(P) site.[8] 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.
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.
^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.
^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. PMID18719951. S2CID3303144.((cite journal)): CS1 maint: multiple names: authors list (link)
^ abMadueño 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. PMID1391772. S2CID2306978.
^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. PMID9256231. S2CID35375512.
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. PMID18719951. S2CID3303144.((cite journal)): CS1 maint: multiple names: authors list (link)
External links
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
