Summary: Ferredoxin I 4Fe-4S cluster domain
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 "Ironâ€“sulfur 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 email@example.com 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.
Ironâ€“sulfur protein Edit Wikipedia article
Ironâ€“sulfur proteins are proteins characterized by the presence of ironâ€“sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Ironâ€“sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q â€“ cytochrome c reductase, succinate â€“ coenzyme Q reductase and nitrogenase. Ironâ€“sulfur clusters are best known for their role in the oxidation-reduction reactions of electron transport in mitochondria and chloroplasts. Both Complex I and Complex II of oxidative phosphorylation have multiple Feâ€“S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally, some Feâ€“S proteins regulate gene expression. Feâ€“S proteins are vulnerable to attack by biogenic nitric oxide, forming dinitrosyl iron complexes. In most Feâ€“S proteins, the terminal ligands on Fe are thiolate, but exceptions exist.
The prevalence of these proteins on the metabolic pathways of most organisms leads some scientists to theorize that ironâ€“sulfur compounds had a significant role in the origin of life in the ironâ€“sulfur world theory.
In almost all Feâ€“S proteins, the Fe centers are tetrahedral and the terminal ligands are thiolato sulfur centers from cysteinyl residues. The sulfide groups are either two- or three-coordinated. Three distinct kinds of Feâ€“S clusters with these features are most common.
The simplest polymetallic system, the [Fe2S2] cluster, is constituted by two iron ions bridged by two sulfide ions and coordinated by four cysteinyl ligands (in Fe2S2 ferredoxins) or by two cysteines and two histidines (in Rieske proteins). The oxidized proteins contain two Fe3+ ions, whereas the reduced proteins contain one Fe3+ and one Fe2+ ion. These species exist in two oxidation states, (FeIII)2 and FeIIIFeII. CDGSH iron sulfur domain is also associated with 2Fe-2S clusters.
A common motif features a four iron ions and four sulfide ions placed at the vertices of a cubane-type cluster. The Fe centers are typically further coordinated by cysteinyl ligands. The [Fe4S4] electron-transfer proteins ([Fe4S4] ferredoxins) may be further subdivided into low-potential (bacterial-type) and high-potential (HiPIP) ferredoxins. Low- and high-potential ferredoxins are related by the following redox scheme:
In HiPIP, the cluster shuttles between [2Fe3+, 2Fe2+] (Fe4S42+) and [3Fe3+, Fe2+] (Fe4S43+). The potentials for this redox couple range from 0.4 to 0.1 V. In the bacterial ferredoxins, the pair of oxidation states are [Fe3+, 3Fe2+] (Fe4S4+) and [2Fe3+, 2Fe2+] (Fe4S42+). The potentials for this redox couple range from âˆ’0.3 to âˆ’0.7 V. The two families of 4Feâ€“4S clusters share the Fe4S42+ oxidation state. The difference in the redox couples is attributed to the degree of hydrogen bonding, which strongly modifies the basicity of the cysteinyl thiolate ligands. A further redox couple, which is still more reducing than the bacterial ferredoxins is implicated in the nitrogenase.
Some 4Feâ€“4S clusters bind substrates and are thus classified as enzyme cofactors. In aconitase, the Feâ€“S cluster binds aconitate at the one Fe centre that lacks a thiolate ligand. The cluster does not undergo redox, but serves as a Lewis acid catalyst to convert citrate to isocitrate. In radical SAM enzymes, the cluster binds and reduces S-adenosylmethionine to generate a radical, which is involved in many biosyntheses.
Proteins are also known to contain [Fe3S4] centres, which feature one iron less than the more common [Fe4S4] cores. Three sulfide ions bridge two iron ions each, while the fourth sulfide bridges three iron ions. Their formal oxidation states may vary from [Fe3S4]+ (all-Fe3+ form) to [Fe3S4]2âˆ’ (all-Fe2+ form). In a number of ironâ€“sulfur proteins, the [Fe4S4] cluster can be reversibly converted by oxidation and loss of one iron ion to a [Fe3S4] cluster. E.g., the inactive form of aconitase possesses an [Fe3S4] and is activated by addition of Fe2+ and reductant.
Other Feâ€“S clusters
More complex polymetallic systems are common. Examples include both the 8Fe and the 7Fe clusters in nitrogenase. Carbon monoxide dehydrogenase and the [FeFe]-hydrogenase also feature unusual Feâ€“S clusters. A special 6 cysteine-coordinated [Fe4S3] cluster was found in oxygen-tolerant membrane-bound [NiFe] hydrogenases.
The biosynthesis of the Feâ€“S clusters has been well studied. The biogenesis of iron sulfur clusters has been studied most extensively in the bacteria E. coli and A. vinelandii and yeast S. cerevisiae. At least three different biosynthetic systems have been identified so far, namely nif, suf, and isc systems, which were first identified in bacteria. The nif system is responsible for the clusters in the enzyme nitrogenase. The suf and isc systems are more general. The yeast isc system is the best described. Several proteins constitute the biosynthetic machinery via the isc pathway. The process occurs in two major steps: (1) the Fe/S cluster is assembled on a scaffold protein followed by (2) transfer of the preformed cluster to the recipient proteins. The first step of this process occurs in the cytoplasm of prokaryotic organisms or in the mitochondria of eukaryotic organisms. In the higher organisms the clusters are therefore transported out of the mitochondrion to be incorporated into the extramitochondrial enzymes. These organisms also possess a set of proteins involved in the Fe/S clusters transport and incorporation processes that are not homologous to proteins found in prokaryotic systems.
Synthetic analogues of the naturally occurring Feâ€“S clusters were first reported by Holm and coworkers. Treatment of iron salts with a mixture of thiolates and sulfide affords derivatives such as (Et4N)2Fe4S4(SCH2Ph)4].
- S. J. Lippard, J. M. Berg â€œPrinciples of Bioinorganic Chemistryâ€ University Science Books: Mill Valley, CA; 1994. ISBN 0-935702-73-3.
- Bak, D. W.; Elliott, S. J. (2014). "Alternative FeS cluster ligands: tuning redox potentials and chemistry". Curr. Opin. Chem. Biol. 19: 50â€“58. doi:10.1016/j.cbpa.2013.12.015.
- Susan C. Wang; Perry A. Frey (2007). "S-adenosylmethionine as an oxidant: the radical SAM superfamily". Trends in Biochemical Sciences. 32 (3): 101â€“10. doi:10.1016/j.tibs.2007.01.002. PMID 17291766.
- Fritsch, J; Scheerer, P; Frielingsdorf, S; Kroschinsky, S; Friedrich, B; Lenz, O; Spahn, CMT (2011-10-16). "The crystal structure of an oxygen-tolerant hydrogenase uncovers a novel iron-sulphur centre". Nature. 479 (7372): 249â€“252. doi:10.1038/nature10505. PMID 22002606.
- Shomura, Y; Yoon, KS; Nishihara, H; Higuchi, Y (2011-10-16). "Structural basis for a [4Fe-3S] cluster in the oxygen-tolerant membrane-bound [NiFe]-hydrogenase". Nature. 479 (7372): 253â€“256. doi:10.1038/nature10504. PMID 22002607.
- Johnson D, Dean DR, Smith AD, Johnson MK (2005). "Structure, function and formation of biological ironâ€“sulfur clusters". Annual Review of Biochemistry. 74 (1): 247â€“281. doi:10.1146/annurev.biochem.74.082803.133518. PMID 15952888.
- Johnson, M.K. and Smith, A.D. (2005) Ironâ€“sulfur proteins in: Encyclopedia of Inorganic Chemistry (King, R.B., Ed.), 2nd edn, John Wiley & Sons, Chichester.
- Lill R, MÃ¼hlenhoff U (2005). "Ironâ€“sulfur-protein biogenesis in eukaryotes". Trends in Biochemical Sciences. 30 (3): 133â€“141. doi:10.1016/j.tibs.2005.01.006. PMID 15752985.
- T. Herskovitz; B. A. Averill; R. H. Holm; J. A. Ibers; W. D. Phillips; J. F. Weiher (1972). "Structure and Properties of a Synthetic Analogue of Bacterial Iron-Sulfur Proteins". Proceedings of the National Academy of Sciences. 69 (9): 2437â€“2441. doi:10.1073/pnas.69.9.2437. PMC 426959. PMID 4506765.
- Holm, R. H.; Lo, W. (2016). "Structural Conversions of Synthetic and Protein-Bound Iron-Sulfur Clusters". Chem. Rev. 116: 13685â€“13713. doi:10.1021/acs.chemrev.6b00276.
- Lee, S. C.; Lo, W.; Holm, R. H. (2014). "Developments in the Biomimetic Chemistry of Cubane-Type and Higher Nuclearity Ironâ€“Sulfur Clusters". Chemical Reviews. 114: 3579â€“3600. doi:10.1021/cr4004067. PMC 3982595. PMID 24410527.
- Beinert, H. (2000). "Iron-sulfur proteins: ancient structures, still full of surprises". J. Biol. Inorg. Chem. 5 (1): 2â€“15. doi:10.1007/s007750050002. PMID 10766431.
- Beinert, H.; Kiley, P.J. (1999). "Fe-S proteins in sensing and regulatory functions". Curr. Opin. Chem. Biol. 3 (2): 152â€“157. doi:10.1016/S1367-5931(99)80027-1. PMID 10226040.
- Johnson, M.K. (1998). "Iron-sulfur proteins: new roles for old clusters". Curr. Opin. Chem. Biol. 2 (2): 173â€“181. doi:10.1016/S1367-5931(98)80058-6. PMID 9667933.
- Nomenclature Committee of the International Union of Biochemistry (NC-IUB) (1979). "Nomenclature of iron-sulfur proteins. Recommendations 1978". Eur. J. Biochem. 93 (3): 427â€“430. doi:10.1111/j.1432-1033.1979.tb12839.x. PMID 421685.
- Noodleman, L., Lovell, T., Liu, T., Himo, F. and Torres, R.A. (2002). "Insights into properties and energetics of iron-sulfur proteins from simple clusters to nitrogenase". Curr. Opin. Chem. Biol. 6 (2): 259â€“273. doi:10.1016/S1367-5931(02)00309-5. PMID 12039013.CS1 maint: multiple names: authors list (link)
- Spiro, T.G., Ed. (1982). Iron-sulfur proteins. New York: Wiley. ISBN 0-471-07738-0.CS1 maint: multiple names: authors list (link)
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.
Ferredoxin I 4Fe-4S cluster domain Provide feedback
This is domain is found in Ferredoxin I (FdI), an Iron-sulfur ([Fe-S]) cluster-containing protein, present in species such as Azotobacter vinelandii. [Fe-S] proteins participate in electron transfer, catalytic, regulatory, and structural function. The FdI cluster exhibits a pH-dependent reduction potential and reversible protonation in the reduced state .
Schipke CG, Goodin DB, McRee DE, Stout CD;, Biochemistry. 1999;38:8228-8239.: Oxidized and reduced Azotobacter vinelandii ferredoxin I at 1.4 A resolution: conformational change of surface residues without significant change in the [3Fe-4S]+/0 cluster. PUBMED:10387068 EPMC:10387068
This tab holds annotation information from the InterPro database.
No InterPro data for this Pfam family.
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...
Superfamily includes proteins containing domains which bind to iron-sulfur clusters. Members include bacterial ferredoxins, various dehydrogenases and various reductases. The structure of the domain is an alpha-antiparallel beta sandwich.
The clan contains the following 29 members:ETF_QO Fer4 Fer4_10 Fer4_11 Fer4_12 Fer4_13 Fer4_14 Fer4_15 Fer4_16 Fer4_17 Fer4_18 Fer4_19 Fer4_2 Fer4_20 Fer4_21 Fer4_22 Fer4_23 Fer4_24 Fer4_3 Fer4_4 Fer4_5 Fer4_6 Fer4_7 Fer4_8 Fer4_9 FeS Molybdop_Fe4S4 Nitr_red_alph_N RLI
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 (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the UniProtKB sequence database, 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 UniProtKB sequence database using the family HMM
- 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.
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.
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:||3|
|Number in full:||330|
|Average length of the domain:||34.90 aa|
|Average identity of full alignment:||66 %|
|Average coverage of the sequence by the domain:||4.19 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 47079205 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||2|
|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.
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 Fer4_24 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 sequence.
Loading structure mapping...