Histidine decarboxylase proenzyme (IPR003427)

Short name: His_de-COase_proenz

Overlapping homologous superfamilies

Family relationships



Histidine decarboxylase (EC: catalyses the formation of histamine from histidine [PMID: 11243783]. It requires a pyruvoyl group for its activity. Cleavage of the proenzyme PI chain yields two subunits, alpha and beta, which arrange as a hexamer (alpha beta) 6 by nonhydrolytic self-catalysis.

In Lactobacillus cells, pyruvoyl-dependent histidine decarboxylase functions to counter the effects of acidic fermentation products, thus modifying extracellular pH. Cells take up histidine and decarboxylate it using histidine decarboxylase to consume a proton and produce histamine, which the cells excrete. These proteins are all dependent on the pyruvoyl cofactor, which is part of the active site and is located at the amino terminus of the alpha-chain (corresponding to residue 82 of the proenzyme in Lactobacillus sp. 30a), at the break between the beta and alpha chains. This pyruvoyl cofactor facilitates decarboxylation via a Schiff base mechanism resembling that of the more common PLP-dependent decarboxylases. This covalent intermediate allows for resonance stabilisation, facillitaing the decarboxylation step. The mechanism for this enzyme can be found in MACiE entry M0049 [PMID: 2745463, PMID: 8490030, PMID: 2197977].

GO terms

Biological Process

GO:0006547 histidine metabolic process

Molecular Function

GO:0004398 histidine decarboxylase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
  • PD024462 (Pyruvoyl-dep_his_de-COase_PI)