Summary: Cytochrome B6-F complex Fe-S subunit
Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.
This is the Wikipedia entry entitled "Rieske protein". More...
The Wikipedia text that you see displayed here is a download from Wikipedia. This means that the information we display is a copy of the information from the Wikipedia database. The button next to the article title ("Edit Wikipedia article") takes you to the edit page for the article directly within Wikipedia. You should be aware you are not editing our local copy of this information. Any changes that you make to the Wikipedia article will not be displayed here until we next download the article from Wikipedia. We currently download new content on a nightly basis.
Does Pfam agree with the content of the Wikipedia entry ?
Pfam has chosen to link families to Wikipedia articles. In some case we have created or edited these articles but in many other cases we have not made any direct contribution to the content of the article. The Wikipedia community does monitor edits to try to ensure that (a) the quality of article annotation increases, and (b) vandalism is very quickly dealt with. However, we would like to emphasise that Pfam does not curate the Wikipedia entries and we cannot guarantee the accuracy of the information on the Wikipedia page.
Editing Wikipedia articles
Before you edit for the first time
Wikipedia is a free, online encyclopedia. Although anyone can edit or contribute to an article, Wikipedia has some strong editing guidelines and policies, which promote the Wikipedia standard of style and etiquette. Your edits and contributions are more likely to be accepted (and remain) if they are in accordance with this policy.
You should take a few minutes to view the following pages:
How your contribution will be recorded
Anyone can edit a Wikipedia entry. You can do this either as a new user or you can register with Wikipedia and log on. When you click on the "Edit Wikipedia article" button, your browser will direct you to the edit page for this entry in Wikipedia. If you are a registered user and currently logged in, your changes will be recorded under your Wikipedia user name. However, if you are not a registered user or are not logged on, your changes will be logged under your computer's IP address. This has two main implications. Firstly, as a registered Wikipedia user your edits are more likely seen as valuable contribution (although all edits are open to community scrutiny regardless). Secondly, if you edit under an IP address you may be sharing this IP address with other users. If your IP address has previously been blocked (due to being flagged as a source of 'vandalism') your edits will also be blocked. You can find more information on this and creating a user account at Wikipedia.
If you have problems editing a particular page, contact us at firstname.lastname@example.org and we will try to help.
The community annotation is a new facility of the Pfam web site. If you have problems editing or experience problems with these pages please contact us.
Rieske protein Edit Wikipedia article
|Cytochrome B6-F complex Fe-S subunit, alpha helical transmembrane domain|
crystal structure of cytochrome b6f complex from m.laminosus
Rieske proteins are iron-sulfur protein (ISP) components of cytochrome bc1 complexes and cytochrome b6f complexes 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.
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 oxidoreduction of the mobile redox components ubiquinol and cytochrome c, generating an electrochemical potential difference, 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 cytochrome c or cytochrome f 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.
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 22.214.171.124). Comparison of amino acid sequences has revealed the following consensus sequence:
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.
Human proteins containing this domain
- 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. PMID 18719951.
- 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.
- 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.
- 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.
- 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.
- 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.
- Iwata S, Saynovits M, Link TA, Michel H (May 1996). "Structure of a water soluble fragment of the 'Rieske' iron-sulfur protein of the bovine heart mitochondrial cytochrome bc1 complex determined by MAD phasing at 1.5 A resolution". Structure 4 (5): 567–79. doi:10.1016/S0969-2126(96)00062-7. PMID 8736555.
- Huang JT, Struck F, Matzinger DF, Levings CS (December 1991). "Functional analysis in yeast of cDNA coding for the mitochondrial Rieske iron-sulfur protein of higher plants". Proc. Natl. Acad. Sci. U.S.A. 88 (23): 10716–20. doi:10.1073/pnas.88.23.10716. PMC 53001. PMID 1961737.
- Brandt U, Yu L, Yu CA, Trumpower BL (April 1993). "The mitochondrial targeting presequence of the Rieske iron-sulfur protein is processed in a single step after insertion into the cytochrome bc1 complex in mammals and retained as a subunit in the complex". J. Biol. Chem. 268 (12): 8387–90. PMID 8386158.
- Ferraro, D.J., Gakhar, L. and Ramaswamy, S. (2005). "Rieske business: structure-function of Rieske non-heme oxygenases". Biochem. Biophys. Res. Commun. 338 (1): 175–190. doi:10.1016/j.bbrc.2005.08.222. PMID 16168954.
- Mason, J.R. and Cammack, R. (1992). "The electron-transport proteins of hydroxylating bacterial dioxygenases". Annu. Rev. Microbiol. 46: 277–305. doi:10.1146/annurev.mi.46.100192.001425. PMID 1444257.
- Schmidt, C.L. (2004). "Rieske iron-sulfur proteins from extremophilic organisms". J. Bioenerg. Biomembr. 36 (1): 107–113. doi:10.1023/B:JOBB.0000019602.96578.78. PMID 15168614.
- Schneider, D. and Schmidt, C.L. (2005). "Multiple Rieske proteins in prokaryotes: where and why?". Biochim. Biophys. Acta 1710 (1): 1–12. doi:10.1016/j.bbabio.2005.09.003. PMID 16271700.
- 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.
- 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
- IPR005806 - InterPro entry for Rieske [2Fe-2S] region
This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.
Cytochrome B6-F complex Fe-S subunit Provide feedback
The cytochrome B6-F complex mediates electron transfer between photosystem II (PSII) and photosystem I (PSI), cyclic electron flow around PSI, and state transitions. This domain corresponds to the alpha helical transmembrane domain of the cytochrome B6-F complex iron-sulphur subunit.
Internal database links
|Similarity to PfamA using HHSearch:||UCR_Fe-S_N|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR014909
The cytochrome b6-f complex mediates electron transfer between photosystem II (PSII) and photosystem I (PSI), cyclic electron flow around PSI, and state transitions. The cytochrome b6-f complex has 4 large subunits, these are: cytochrome b6, subunit IV (17 kDa polypeptide, PetD), cytochrome f and the Rieske protein, while the 4 small subunits are: PetG, PetL, PetM and PetN. The complex functions as a dimer.
This protein corresponds to the alpha helical transmembrane domain of the cytochrome b6-f complex Rieske iron-sulphur subunit.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||thylakoid membrane (GO:0042651)|
|Molecular function||plastoquinol--plastocyanin reductase activity (GO:0009496)|
|2 iron, 2 sulfur cluster binding (GO:0051537)|
|Biological process||oxidation-reduction process (GO:0055114)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
Loading domain graphics...
We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
- a Java applet developed at the University of Dundee. You will need Java installed before running jalview
- an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
- an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
- Pfam viewer
- an HTML-based viewer that uses DAS to retrieve alignment fragments on request
You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.
You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.
We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.
HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...
If you find these logos useful in your own work, please consider citing the following article:
This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.
Note: You can also download the data file for the tree.
Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
|Number in seed:||19|
|Number in full:||215|
|Average length of the domain:||37.50 aa|
|Average identity of full alignment:||46 %|
|Average coverage of the sequence by the domain:||19.78 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||5|
|Download:||download the raw HMM for this family|
Weight segments by...
Change the size of the sunburst
selected sequences to HMM
a FASTA-format file
- 0 sequences
- 0 species
This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
Missing taxonomic levels
Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
You can use the tree controls to manipulate how the interactive tree is displayed:
- show/hide the summary boxes
- highlight species that are represented in the seed alignment
- expand/collapse the tree or expand it to a given depth
- select a sub-tree or a set of species within the tree and view them graphically or as an alignment
- save a plain text representation of the tree
Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.
There are 4 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the CytB6-F_Fe-S domain has been found. There are 9 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
Loading structure mapping...