Rieske proteins are
iron–sulfur protein
Iron–sulfur proteins (or iron–sulphur proteins in British spelling) are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clu ...
(ISP) components of
cytochrome ''bc''1 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.
In 1979 Trumpower's lab isolated the "oxidation factor" from bovine
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
and showed it was a reconstitutively-active form of the Rieske iron-sulfur protein
It is a unique
Fe-2Scluster in that one of the two Fe atoms is coordinated by two
histidine
Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the de ...
residues rather than two
cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile.
When present as a deprotonated catalytic residue, sometime ...
residues. They have since been found in plants, animals, and
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
with widely ranging electron
reduction potential
Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...
s from -150 to +400 mV.
Biological function
Ubiquinol-cytochrome-c reductase (also known as bc1 complex or complex III) is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
complex of bacterial and mitochondrial
oxidative phosphorylation
Oxidative phosphorylation (UK , US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine tri ...
systems. It catalyses the
oxidation-reduction reaction
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...
of the mobile components
ubiquinol
A ubiquinol is an electron-rich (reduced) form of coenzyme Q (ubiquinone). The term most often refers to ubiquinol-10, with a 10-unit tail most commonly found in humans.
The natural ubiquinol form of coenzyme Q is 2,3-dimethoxy-5-methyl-6-poly ...
and
cytochrome c
The cytochrome complex, or cyt ''c'', is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins and plays a major role in cell apoptosis. Cytochrome c is hig ...
, contributing to an
electrochemical potential
In electrochemistry, the electrochemical potential (ECP), ', is a thermodynamic measure of chemical potential that does not omit the energy contribution of electrostatics. Electrochemical potential is expressed in the unit of J/ mol.
Introductio ...
difference across the mitochondrial inner or
bacterial membrane, which is linked to
ATP synthesis
ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). It is classified under ligases as it changes ADP by the formation ...
.
The complex consists of three subunits in most bacteria, and nine in mitochondria: both bacterial and mitochondrial complexes contain
cytochrome b
Cytochrome b within both molecular and cell biology, is a protein found in the mitochondria of eukaryotic cells. It functions as part of the electron transport chain and is the main subunit of transmembrane cytochrome bc1 and b6f complexes.
F ...
and
cytochrome c1
Cytochrome C1 (also known as Complex III subunit 4) is a protein encoded by the ''CYC1'' gene. Cytochrome is a heme-containing subunit of the cytochrome b-c1 complex, which accepts electrons from Rieske protein and transfers electrons to cytochr ...
subunits, and an iron–sulfur '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
Plastoquinone (PQ) is an isoprenoid quinone molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone m ...
-
plastocyanin
Plastocyanin is a copper-containing protein that mediates electron-transfer. It is found in a variety of plants, where it participates in photosynthesis. The protein is a prototype of the blue copper proteins, a family of intensely blue-colored m ...
reductase (b6f complex), present in
cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...
and the
chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
s of plants,
catalyses the oxidoreduction of
plastoquinol
Plastoquinone (PQ) is an isoprenoid quinone molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone mol ...
and
cytochrome f
Cytochrome ''f'' is the largest subunit of cytochrome ''b''6''f'' complex (plastoquinol—plastocyanin reductase; ). In its structure and functions, the cytochrome b6f complex bears extensive analogy to the cytochrome bc1 complex of mitochondr ...
. 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
A ubiquinol is an electron-rich (reduced) form of coenzyme Q (ubiquinone). The term most often refers to ubiquinol-10, with a 10-unit tail most commonly found in humans.
The natural ubiquinol form of coenzyme Q is 2,3-dimethoxy-5-methyl-6-poly ...
or
plastoquinol
Plastoquinone (PQ) is an isoprenoid quinone molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis. The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone mol ...
anion, transferring an electron to the 2Fe-2S cluster, then releasing the electron to the
cytochrome c
The cytochrome complex, or cyt ''c'', is a small hemeprotein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins and plays a major role in cell apoptosis. Cytochrome c is hig ...
or
cytochrome f
Cytochrome ''f'' is the largest subunit of cytochrome ''b''6''f'' complex (plastoquinol—plastocyanin reductase; ). In its structure and functions, the cytochrome b6f complex bears extensive analogy to the cytochrome bc1 complex of mitochondr ...
heme iron.
The reduction of the Rieske center increases the affinity of the subunit by several orders of magnitude, stabilizing the
semiquinone
Semiquinone (or ubisemiquinone) is a free radical resulting from the removal of one hydrogen atom with its electron during the process of dehydrogenation of a hydroquinone, such as hydroquinone itself or catechol, to a quinone or alternatively the ...
radical
Radical may refer to:
Politics and ideology Politics
*Radical politics, the political intent of fundamental societal change
*Radicalism (historical), the Radical Movement that began in late 18th century Britain and spread to continental Europe and ...
at the Q(P) site.
The Rieske domain has a
Fe-2Scenter. Two conserved
cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile.
When present as a deprotonated catalytic residue, sometime ...
s 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 ''b''6''f'' complex,
aromatic-ring-hydroxylating dioxygenases (phthalate dioxygenase,
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
,
naphthalene
Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromati ...
and
toluene
Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) at ...
1,2-dioxygenases) and arsenite oxidase (
ECbr>
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 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 alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...
. 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
2S2">e2S2cluster-binding subdomains have the topology of an incomplete antiparallel β-barrel. One iron atom of the Rieske
2S2">e2S2cluster in the domain is coordinated by two
cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile.
When present as a deprotonated catalytic residue, sometime ...
residues and the other is coordinated by two
histidine
Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the de ...
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
Apoptosis-inducing factor, mitochondria-associated 3 is a protein that in humans is encoded by the AIFM3 gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." m ...
;
RFESD;
UQCRFS1
Ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1, also known as UQCRFS1, Rieske iron-sulfur (Fe-S) protein, Cytochrome b-c1 complex subunit 5, or Complex III subunit 5 is a protein which in humans is encoded by the ''UQCRFS1'' ge ...
;
References
Further reading
*
*
*
*
*
*
*
*
External links
* - X-ray structure of Rieske protein (water-soluble fragment) of the bovine mitochondrial cytochrome ''bc''
1 complex
* - X-ray structure of Rieske protein (water-soluble fragment) of the spinach chloroplast cytochrome ''b''
6'' f''complex
* - 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
''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...
Naphthalene 1,2-dioxygenase Rieske ferredoxin
* {{InterPro, IPR005806 - InterPro entry for Rieske
Fe-2Sregion
Iron–sulfur proteins
Protein domains
Peripheral membrane proteins