title: Location of the dihydroorotase domain within trifunctional hamster dihydroorotate synthetase.
abstract: Mammalian dihydroorotase (DHOase, EC 3.5.2.3) is part of a trifunctional protein, dihydroorotate synthetase which catalyzes the first three reactions of de novo pyrimidine biosynthesis. We have subcloned a portion of the cDNA from the plasmid pCAD142 and obtained a nucleotide sequence which extends 2.1 kb in the 5' direction from the sequence encoding the aspartate transcarbamoylase (ATCase) domain at the 3'-end of the cDNA. The DHOase and ATCase domains have been purified from an elastase digest of the trifunctional protein and subjected to amino acid (aa) sequencing from their N termini. The sequence of the N-terminal 24 aa of the DHOase domain has been obtained and aligned with the cDNA sequence. The C-terminal residues of the DHOase domain have been identified as Leu followed by Val which, when taken with partial sequences of the CNBr fragments of this domain, defines the coding sequence of the active, globular DHOase domain released by proteolysis. Prediction of protein secondary structure from the deduced aa sequence showed that the DHOase domain (Mr 37,751) is separated from the C-terminal ATCase domain (Mr 34,323) by a bridging sequence (Mr 12,532) consisting of multiple beta-turns.
authors.affiliation: Department of Biochemistry, University of Sydney, New South Wales, Australia.
authors.forename: N K
authors.initials: NK
authors.lastname: Williams
authors.forename: R J
authors.initials: RJ
authors.lastname: Simpson
authors.forename: R L
authors.initials: RL
authors.lastname: Moritz
authors.forename: Y
authors.initials: Y
authors.lastname: Peide
authors.forename: L
authors.initials: L
authors.lastname: Crofts
authors.forename: E
authors.initials: E
authors.lastname: Minasian
authors.forename: S J
authors.initials: SJ
authors.lastname: Leach
authors.forename: R G
authors.initials: RG
authors.lastname: Wake
authors.forename: R I
authors.initials: RI
authors.lastname: Christopherson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001221:Aspartate Carbamoyltransferase / Q000648:ultrastructure; D001483:Base Sequence; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000648:ultrastructure; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000302:isolation & purification; D004080:Dihydroorotase / Q000235:genetics* / Q000648:ultrastructure; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000648:ultrastructure; D016366:Open Reading Frames / Q000235:genetics; D010957:Plasmids; D011743:Pyrimidines / Q000096:biosynthesis; D012689:Sequence Homology, Nucleic Acid
chemical_list: C033626:CAD trifunctional enzyme; D009097:Multienzyme Complexes; D011743:Pyrimidines; D004247:DNA; D001221:Aspartate Carbamoyltransferase; D004080:Dihydroorotase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing); C030986:pyrimidine