Binding Site

Porphobilinogen deaminase, dipyrromethane cofactor binding site (IPR022419)

Short name: Porphobilin_deaminase_cofac_BS


This entry represents the region around a cysteine residues that is conserved in porphobilinogen deaminases from various prokaryotic and eukaryotic sources. The sulphur atom of this cysteine residue has been shown in the Escherichia coli enzyme (gene hemC) to be bound to the dipyrromethane cofactor [PMID: 3196304]. Porphobilinogen deaminase covalently binds a dipyrromethane cofactor to which the PBG subunits are added in a stepwise fashion. Porphobilinogen deaminase has a three-domain structure. Domains 1 (N-terminal) and 2 are duplications with the same structure, resembling the transferrins and periplasmic binding proteins. The dipyrromethane cofactor is covalently linked to domain 3 (C-terminal), but is bound by extensive salt-bridges and hydrogen-bonds within the cleft between domains 1 and 2, at a position corresponding to the binding sites for small-molecule ligands in the analogous proteins [PMID: 1522882]. The enzyme has a single catalytic site, and the flexibility between domains is thought to aid elongation of the polypyrrole product in the active-site cleft of the enzyme.

GO terms

Biological Process

GO:0018160 peptidyl-pyrromethane cofactor linkage
GO:0033014 tetrapyrrole biosynthetic process

Molecular Function

GO:0004418 hydroxymethylbilane synthase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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