Acireductone dioxygenase ARD family (IPR004313)

Short name: ARD

Overlapping homologous superfamilies

Family relationships


The two acireductone dioxygenase enzymes (ARD and ARD', previously known as E-2 and E-2') from Klebsiella pneumoniae share the same amino acid sequence Q9ZFE7, but bind different metal ions: ARD binds Ni2+, ARD' binds Fe2+ [PMID: 9880484]. ARD and ARD' can be experimentally interconverted by removal of the bound metal ion and reconstitution with the appropriate metal ion. The two enzymes share the same substrate, 1,2-dihydroxy-3-keto-5-(methylthio)pentene, but yield different products. ARD' yields the alpha-keto precursor of methionine (and formate), thus forming part of the ubiquitous methionine salvage pathway that converts 5'-methylthioadenosine (MTA) to methionine. This pathway is responsible for the tight control of the concentration of MTA, which is a powerful inhibitor of polyamine biosynthesis and transmethylation reactions [PMID: 11371200]. ARD yields methylthiopropanoate, carbon monoxide and formate, and thus prevents the conversion of MTA to methionine. The role of the ARD catalysed reaction is unclear: methylthiopropanoate is cytotoxic, and carbon monoxide can activate guanylyl cyclase, leading to increased intracellular cGMP levels [PMID: 11371200, PMID: 9880484].

Eukaryotic aci-reductone dioxygenase (ARD), also known as 1,2-dihydroxy-3-keto-5-methylthiopentene dioxygenase, acts in the methionine salvage pathway [PMID: 15938715]. Several homologous ARD genes have been identified in plants [PMID: 16297065].

GO terms

Biological Process

GO:0055114 oxidation-reduction process

Molecular Function

GO:0010309 acireductone dioxygenase [iron(II)-requiring] activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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