| Type: | Conserved_site | Name: | Dihydroorotase, conserved site |
| Description: | This group contains a number of protein families, example are:Archaeal and bacterial dihydroorotase () (DHOase)Allantoinase ()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 novobiosynthesis 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 [].In bacteria, DHOase is a dimer of identical chains of about 400 amino-acid residues (gene pyrC) []. In higher eukaryotes, DHOase is part of a large multi-functional protein known as 'rudimentary' in Drosophila melanogasterand CAD in mammals and which catalyzes the first three steps of pyrimidine biosynthesis []. The DHOase domain is located in the central part of this polyprotein. In yeasts, DHOase is encoded by a monofunctional protein (gene URA4). However, a defective DHOase domain [] 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 [] that there are two highly conserved regions. The first located in the N-terminal extremity contains two histidine residues suggested [] 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 [].Allantoinase () is the enzyme that hydrolyzes allantoin into allantoate. In yeast (gene DAL1) [], it is the first enzyme in the allantoin degradation pathway; in amphibians [] and fishs it catalyzes the second step in the degradation of uric acid. The sequence of allantoinase is evolutionary related to that of DHOases. | Short Name: | Dihydroorotase_CS |
