Imidazoleglycerol-phosphate dehydratase (IPR000807)

Short name: ImidazoleglycerolP_deHydtase

Overlapping homologous superfamilies


Family relationships



Imidazoleglycerol-phosphate dehydratase (IGPD; EC: catalyzes the dehydration of imidazole glycerol phosphate to imidazole acetol phosphate, the sixth step of histidine biosynthesis in plants and microorganisms where the histidine is synthesized de novo. There is an internal repeat in the protein domain that is related by pseudo-dyad symmetry, perhaps as a result of an ancient gene duplication. The apo-form of IGPD exists as a catalytically inactive trimer which, in the presence of specific divalent metal cations such as manganese (Mn2+), cobalt (Co2+), cadmium (Cd2+), nickel (Ni2+), iron (Fe2+) and zinc (Zn2+), assembles to form a biologically active high molecular weight metalloenzyme; a 24-mer with 4-3-2 symmetry. Each 24-mer has 24 active sites, and contains around 1.5 metal ions per monomer, each monomer contributing residues to three separate active sites.

IGPD enzymes are monofunctional in fungi, plants, archaea and some eubacteria while they are encoded as bifunctional enzymes in other eubacteria, such that the enzyme is fused to histidinol-phosphate phosphatase, the penultimate enzyme of the histidine biosynthesis pathway. The histidine biosynthesis pathway is a potential target for development of herbicides, and IGPD is a target for the triazole phosphonate herbicides [PMID: 16338409, PMID: 14724278, PMID: 15042344, PMID: 10885480, PMID: 16511155, PMID: 10450980, PMID: 8066131, PMID: 3001645, PMID: 9767718, PMID: 8511965, PMID: 2664449, PMID: 3007936].

GO terms

Biological Process

GO:0000105 histidine biosynthetic process

Molecular Function

GO:0004424 imidazoleglycerol-phosphate dehydratase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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