Domain

Aconitase A/isopropylmalate dehydratase small subunit, swivel domain (IPR000573)

Short name: AconitaseA/IPMdHydase_ssu_swvl

Domain relationships

Description

Aconitase (aconitate hydratase; EC:4.2.1.3) is an iron-sulphur protein that contains a [4Fe-4S]-cluster and catalyses the interconversion of isocitrate and citrate via a cis-aconitate intermediate. Aconitase functions in both the TCA and glyoxylate cycles, however unlike the majority of iron-sulphur proteins that function as electron carriers, the [4Fe-4S]-cluster of aconitase reacts directly with an enzyme substrate. In eukaryotes there is a cytosolic form (cAcn) and a mitochondrial form (mAcn) of the enzyme. In bacteria there are also 2 forms, aconitase A (AcnA) and B (AcnB). Several aconitases are known to be multi-functional enzymes with a second non-catalytic, but essential function that arises when the cellular environment changes, such as when iron levels drop [PMID: 10087914, PMID: 15877277]. Eukaryotic cAcn and mAcn, and bacterial AcnA have the same domain organisation, consisting of three N-terminal alpha/beta/alpha domains, a linker region, followed by a C-terminal 'swivel' domain with a beta/beta/alpha structure (1-2-3-linker-4), although mAcn is small than cAcn. However, bacterial AcnB has a different organisation: it contains an N-terminal HEAT-like domain, followed by the 'swivel' domain, then the three alpha/beta/alpha domains (HEAT-4-1-2-3) [PMID: 9020582].

This entry represents the 'swivel' domain found at the C-terminal of eukaryotic mAcn, cAcn/IPR1 and IRP2, and bacterial AcnA. This domain has a three layer beta/beta/alpha structure, and in cytosolic Acn is known to rotate between the cAcn and IRP1 forms of the enzyme. This domain is also found in the small subunit of isopropylmalate dehydratase (LeuD).

3-isopropylmalate dehydratase (or isopropylmalate isomerase; EC:4.2.1.33) 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 [PMID: 9020582].

GO terms

Biological Process

GO:0008152 metabolic process

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam