Conserved Site

Isopenicillin N synthase, conserved site (IPR002057)

Short name: Isopenicillin-N_synth_CS


Isopenicillin N synthase (IPNS) is a nonhaem-Fe2+-dependent enzyme that belongs to a class of nonhaem Fe2+-containing enzymes, which includes 2-oxoglutarate-dependent dioxygenases, 2-oxoglutarate-dependent hydroxy- lases, and enzymes involved in ethylene formation and anthocyaninidin biosynthesis. IPNS catalyses the stereospecific formation of the beta-lactam and thiazolidine rings of IPN via a 4-electron oxidation of the tripeptide ACV. The enzyme uses, as the sole electron acceptor, one molecule of dioxygen, which is completely reduced to two molecules of water. The oxygen stoichiometry shown by IPNS is the same as that for cytochrome C oxidase, but is unusual for nonhaem-iron-containing enzymes, which typically catalyse the transfer of one or both atoms of dioxygen into their substrates. IPNS thus provides an interesting contrast to dioxygenase enzymes.

Two cysteines are conserved in fungal and bacterial IPNS sequences; these may be involved in iron-binding and/or substrate-binding.

Cephalosporium acremonium DAOCS/DACS is a bifunctional enzyme involved in cephalosporin biosynthesis. The DAOCS domain, which is structurally related to IPNS, catalyzes the step from penicillin N to deacetoxy-cephalosporin C - used as a substrate by DACS to form deacetylcephalosporin C. Streptomyces clavuligerus possesses a monofunctional DAOCS enzyme (gene cefE) [PMID: 2644235] also related to IPNS.

GO terms

Biological Process

GO:0009058 biosynthetic process
GO:0055114 oxidation-reduction process

Molecular Function

GO:0005506 iron ion binding
GO:0016491 oxidoreductase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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