Summary: Fumarate hydratase (Fumerase)
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 "Fumarase". 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.
Fumarase Edit Wikipedia article
Fumarase (or fumarate hydratase) is an enzyme that catalyzes the reversible hydration/dehydration of fumarate to malate. Fumarase comes in two forms: mitochondrial and cytosolic. The mitochondrial isoenzyme is involved in the Krebs Cycle (also known as the Tricarboxylic Acid Cycle [TCA] or the Citric Acid Cycle), and the cytosolic isoenzyme is involved in the metabolism of amino acids and fumarate. Subcellular localization is established by the presence of a signal sequence on the amino terminus in the mitochondrial form, while subcellular localization in the cytosolic form is established by the absence of the signal sequence found in the mitochondrial variety.
This enzyme participates in 3 metabolic pathways:[clarification needed] citric acid cycle, reductive citric acid cycle (CO2 fixation), and in renal cell carcinoma. Mutations in this gene have been associated with the development of leiomyomas in the skin and uterus in combination with renal cell carcinoma.
This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is (S)-malate hydro-lyase (fumarate-forming). Other names in common use include:
- L-malate hydro-lyase
- (S)-malate hydro-lyase
Figure 2 depicts the fumarase reaction mechanism. Two acid-base groups catalyze proton transfer, and the ionization state of these groups is in part defined by two forms of the enzyme E1 and E2. In E1, the groups exist in an internally neutralized A-H/B: state, while in E2, they occur in a zwitterionic A-/BH+ state. E1 binds fumarate and facilitates its tansformation into malate, and E2 binds malate and facilitates its transformation into fumarate. The two forms must undergo isomerization with each catalytic turnover.
Despite its biological significance, the reaction mechanism of fumarase is not completely understood. The reaction itself can be monitored in either direction; however, it is the formation of fumarate from S-malate in particular that is less understood due to the high pKa value of the HR (Fig. 1) atom that is removed without the aid of any cofactors or coenzymes. However, the reaction from fumarate to L-malate is better understood, and involves a stereospecific hydration of fumarate to produce S-malate by trans-addition of a hydroxyl group and a hydrogen atom through a trans 1,4 addition of a hydroxyl group. Early research into this reaction suggested that the formation of fumarate from S-malate involved dehydration of malate to a carbocationic intermediate, which then loses the alpha proton to form fumarate. This led to the conclusion that in the formation of S-Malate from fumarate E1 elimination, protonation of fumarate to the carbocation was followed by the additional of a hydroxyl group from H2O. However, more recent trials have provided evidence that the mechanism actually takes place through an acid-base catalyzed elimination by means of a carbanionic intermediate E1CB elimination (Figure 2).
The function of fumarase in the citric acid cycle is to facilitate a transition step in the production of energy in the form of NADH. In the cytosol the enzyme functions to metabolize fumarate, which is a byproduct of the urea cycle as well as amino acid catabolism. Studies have revealed that the active site is composed of amino acid residues from three of the four subunits within the tetrameric enzyme.
The primary binding site on fumarase is known as catalytic site A. Studies have revealed that catalytic site A is composed of amino acid residues from three of the four subunits within the tetrameric enzyme. Two potential acid-base catalytic residues in the reaction include His 188 and Lys 324.
There are two classes of fumarases. Classifications depend on the arrangement of their relative subunit, their metal requirement, and their thermal stability. These include class I and class II. Class I fumarases are able to change state or become inactive when subjected to heat or radiation, are sensitive to superoxide anion, are Iron II (Fe2+) dependent, and are dimeric proteins consisting of around 120 kD. Class II fumarases, found in prokaryotes as well as in eukaryotes, are tetrameric enzymes of 200,000 D that contain three distinct segments of significantly homologous amino acids. They are also iron-independent and thermal-stable. Prokaryotes are known to have three different forms of fumarase: Fumarase A, Fumarase B, and Fumarase C. Fumarase C is a part of the class II fumarases, whereas Fumarase A and Fumarase B from Escherichia coli (E. coli) are classified as class I.
Fumarase deficiency is characterized by polyhydramnios and fetal brain abnormalities. In the newborn period, findings include severe neurologic abnormalities, poor feeding, failure to thrive, and hypotonia. Fumarase deficiency is suspected in infants with multiple severe neurologic abnormalities in the absence of an acute metabolic crisis. Inactivity of both cytosolic and mitochondrial forms of fumarase are potential causes. Isolated, increased concentration of fumaric acid on urine organic acid analysis is highly suggestive of fumarase deficiency. Molecular genetic testing for fumarase deficiency is currently available.
Fumarase is prevalent in both fetal and adult tissues. A large percentage of the enzyme is expressed in the skin, parathyroid, lymph, and colon. Mutations in the production and development of fumarase have led to the discovery of several fumarase-related diseases in humans. These include benign mesenchymal tumors of the uterus, leiomyomatosis and renal cell carcinoma, and fumarase deficiency. Germinal mutations in fumarase are associated with two distinct conditions. If the enzyme has missense mutation and in-frame deletions from the 3’ end, fumarase deficiency results. If it contains heterozygous 5’ missense mutation and deletions (ranging from one base pair to the whole gene), then leiomyomatosis and renal cell carcinoma/Reed’s syndrome (multiple cutaneous and uterine leiomyomatosis) could result.
The FH gene is localized to the chromosomal position 1q42.3-q43. The FH gene contains 10 exons.
Crystal structures of fumarase C from Escherichia coli have been observed to have two occupied dicarboxylate binding sites. These are known as the active site and the B site. The active site and B site are both identified as having areas unoccupied by a bound ligand. This so-called ‘free’ crystal structure demonstrates conservation of the active-site water. Similar orientation has been discovered in other fumarase C crystal structures. Crystallographic research on the B site of the enzyme has observed that there is a shift on His129. This information suggests that water is a permanent component of the active site. It also suggests that the use of an imidazole-imidazolium conversion controls access to the allosteric B site.
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [§ 1]
- The interactive pathway map can be edited at WikiPathways: "TCACycle_WP78".
- Based on PDB 1yfm coordinates; Weaver T, Lees M, Zaitsev V, Zaitseva I, Duke E, Lindley P, McSweeny S, Svensson A, Keruchenko J, Keruchenko I, Gladilin K, Banaszak L (July 1998). "Crystal structures of native and recombinant yeast fumarase". J. Mol. Biol. 280 (3): 431–42. doi:10.1006/jmbi.1998.1862. PMID 9665847.
- Figure rendered using UCSF Chimera. Molecular graphics images were produced using the UCSF Chimera package from the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco; Pettersen EF, Goddard TD, Huang CC, Couch GS, Greenblatt DM, Meng EC, Ferrin TE (October 2004). "UCSF Chimera--a visualization system for exploratory research and analysis". J Comput Chem 25 (13): 1605–12. doi:10.1002/jcc.20084. PMID 15264254.
- FH (fumarate hydratase)
- Adrian D. Hegeman; Frey, Perry A. (2007). Enzymatic reaction mechanisms. Oxford [Oxfordshire]: Oxford University Press. ISBN 0-19-512258-5.
- Tadhg P. Begley; McMurry, John (2005). The organic chemistry of biological pathways. Roberts and Co. Publishers. ISBN 0-9747077-1-6.
- Walsh C (1979). Enzymatic reaction mechanisms. San Francisco: W. H. Freeman. ISBN 0-7167-0070-0.
- Estévez M, Skarda J, Spencer J, Banaszak L, Weaver TM (June 2002). "X-ray crystallographic and kinetic correlation of a clinically observed human fumarase mutation". Protein Sci. 11 (6): 1552–7. doi:10.1110/ps.0201502. PMC 2373640. PMID 12021453.
- Lynch AM, Morton CC (2006-07-01). "FH (fumarate hydratase).". Atlas of Genetics and Cytogenetics in Oncology and Haematology.
- Weaver T (October 2005). "Structure of free fumarase C from Escherichia coli". Acta Crystallogr. D Biol. Crystallogr. 61 (Pt 10): 1395–401. doi:10.1107/S0907444905024194. PMID 16204892.
- Fumarase at the US National Library of Medicine Medical Subject Headings (MeSH)
- Structure of Fumarate
- Structure of S-Malate
- Link to Breakdown of Citric Acid Cycle
- Video of Fumarate → (S)L-Malate
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.
Fumarate hydratase (Fumerase) Provide feedback
This family consists of several bacterial fumarate hydratase proteins FumA and FumB. Fumarase, or fumarate hydratase (EC 126.96.36.199), is a component of the citric acid cycle. In facultative anaerobes such as Escherichia coli, fumarase also engages in the reductive pathway from oxaloacetate to succinate during anaerobic growth. Three fumarases, FumA, FumB, and FumC, have been reported in E. coli. fumA and fumB genes are homologous and encode products of identical sizes which form thermolabile dimers of Mr 120,000. FumA and FumB are class I enzymes and are members of the iron-dependent hydrolases, which include aconitase and malate hydratase. The active FumA contains a 4Fe-4S centre, and it can be inactivated upon oxidation to give a 3Fe-4S centre .
Tseng CP, Yu CC, Lin HH, Chang CY, Kuo JT; , J Bacteriol 2001;183:461-467.: Oxygen- and growth rate-dependent regulation of Escherichia coli fumarase (FumA, FumB, and FumC) activity. PUBMED:11133938 EPMC:11133938
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR004646
This entry represents various Fe-S type hydro-lyases, including the alpha subunit from both L-tartrate dehydratase (TtdA; EC) and class 1 fumarate hydratases (EC), which includes both aerobic (FumA) and anaerobic (FumB) types [PUBMED:8371115]. A number of Fe-S cluster-containing hydro-lyases share a conserved motif, including argininosuccinate lyase, adenylosuccinate lyase, aspartase, class I fumarate hydratase (fumarase), and tartrate dehydratase (see INTERPRO). Proteins in this group represent a subset of closely related proteins or modules, including the Escherichia coli tartrate dehydratase alpha chain and the N-terminal region of the class I fumarase (where the C-terminal region is homologous to the tartrate dehydratase beta chain). The activity of archaeal proteins in this group is unknown.
Fumarate hydratase (also known as fumarase) is a component of the citric acid cycle. In facultative anaerobes such as E. coli, fumarase also engages in the reductive pathway from oxaloacetate to succinate during anaerobic growth. Three fumarases, FumA, FumB, and FumC, have been reported in E. coli. fumA and fumB genes are homologous and encode products of identical sizes which form thermolabile dimers of Mr 120,000. FumA and FumB are class I enzymes and are members of the iron-dependent hydrolases, which include aconitase and malate hydratase. The active FumA contains a 4Fe-4S centre, and it can be inactivated upon oxidation to give a 3Fe-4S centre [PUBMED:11133938].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||lyase activity (GO:0016829)|
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.
|Seed source:||Pfam-B_2085 (release 8.0)|
|Number in seed:||170|
|Number in full:||3534|
|Average length of the domain:||274.30 aa|
|Average identity of full alignment:||41 %|
|Average coverage of the sequence by the domain:||60.95 %|
|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:||9|
|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.