| Type: | Family | Name: | 3-isopropylmalate dehydratase, fused small/large subunit |
| Description: | 3-isopropylmalate dehydratase (or isopropylmalate isomerase; ) catalyses the stereo-specific isomerisation of 2-isopropylmalate and 3-isopropylmalate, via the formation of 2-isopropylmaleate. This enzyme performs the second step in the biosynthesis of leucine, and is present in most prokaryotes and many fungal species. The prokaryotic enzyme is a heterodimer composed of a large (LeuC) and small (LeuD) subunit, while the fungal form is a monomeric enzyme. Both forms of isopropylmalate are related and are part of the larger aconitase family []. Aconitases are mostly monomeric proteins which share four domains in common and contain a single, labile [4Fe-4S]cluster. Three structural domains (1, 2 and 3) are tightly packed around the iron-sulphur cluster, while a fourth domain (4) forms a deep active-site cleft. The prokaryotic enzyme is encoded by two adjacent genes, leuC and leuD, corresponding to aconitase domains 1-3 and 4 respectively [, ]. LeuC does not bind an iron-sulphur cluster. It is thought that some prokaryotic isopropylamalate dehydrogenases can also function as homoaconitase , converting cis-homoaconitate to homoisocitric acid in lysine biosynthesis []. Homoaconitase has been identified in higher fungi (mitochondria) and several archaea and one thermophilic species of bacteria, Thermus thermophilus[]. This group represents 3-isopropylmalate dehydratase: with fused small and large subunits [, ]. | Short Name: | 3-IsopropMal_deHydtase_ssu/lsu |
| DB identifier | Type | Name |
|---|---|---|
| IPR015931 | Domain | Aconitase/3-isopropylmalate dehydratase large subunit, alpha/beta/alpha, subdomain 1/3 |
| IPR001030 | Domain | Aconitase/3-isopropylmalate dehydratase large subunit, alpha/beta/alpha domain |
| IPR015932 | Domain | Aconitase/3-isopropylmalate dehydratase large subunit, alpha/beta/alpha, subdomain 2 |
| IPR018136 | Binding_site | Aconitase family, 4Fe-4S cluster binding site |
