Dihydroorotase homodimeric type (IPR004721)

Short name: DHOdimr

Overlapping homologous superfamilies

Family relationships



Dihydroorotase belongs to MEROPS peptidase family M38 (clan MJ), where it is classified as a non-peptidase homologue. DHOase catalyses the third step in the de novo biosynthesis of pyrimidine, the conversion of ureidosuccinic acid (N-carbamoyl-L-aspartate) into dihydroorotate. Dihydroorotase binds a zinc ion which is required for its catalytic activity [PMID: 1671037].

In bacteria, DHOase is a dimer of identical chains of about 400 amino-acid residues (gene pyrC). In the metazoa, DHOase is part of a large multi-functional protein known as 'rudimentary' in Drosophila melanogaster and CAD in mammals and which catalyzes the first three steps of pyrimidine biosynthesis [PMID: 8098212]. The DHOase domain is located in the central part of this polyprotein. In yeast, DHOase is encoded by a monofunctional protein (gene URA4). However, a defective DHOase domain [PMID: 2570735] is found in a multifunctional protein (gene URA2) that catalyzes the first two steps of pyrimidine biosynthesis.

The comparison of DHOase sequences from various sources shows [PMID: 2897615] that there are two highly conserved regions. The first located in the N-terminal extremity contains two histidine residues suggested [PMID: 2570735] to be involved in binding the zinc ion. The second is found in the C-terminal part. Members of this family of proteins are predicted to adopt a TIM barrel fold [PMID: 9144792].

This family represents the homodimeric form of dihydroorotase EC: It is found in bacteria, plants and fungi; URA4 of yeast is a member of this group of sequences.

GO terms

Biological Process

GO:0019856 pyrimidine nucleobase biosynthetic process

Molecular Function

GO:0004151 dihydroorotase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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