title: Sequence, expression and evolutionary relationships of carbamoyl phosphate synthetase I in the toad Xenopus laevis.
abstract: The sequence of carbamoyl phosphate synthetase I (CPSase I) cDNA and expression of the enzyme in liver of the toad Xenopus laevis are reported. CPSase I mRNA increases 6-fold when toads are exposed to high salinity for extended periods of time. The deduced 1,494-amino acid sequence of the CPSase I is homologous to other CPSases and reveals a domain structure and conserved amino acids common to other CPSases. A serine residue (S287) is present where there is a cysteine residue required for glutamine-dependent activity in CPSase Types III and II (Type I CPSases utilize only ammonia as nitrogen-donating substrate). A sequence of DNA 964 bases upstream from the ATG start codon for the CPSase I gene is also reported. Phylogenetic analysis for 30 CPSase isoforms, including X. laevis CPSase I, across a wide spectrum of phyla is reported and discussed. The results are consistent with the views that eukaryotic CPSase II as a multifunctional complex evolved from prokaryotic CPSase II and that CPSase I in terrestrial vertebrates and CPSase III in fishes arose from eukaryotic CPSase II by independent events after the divergence of plants in eukaryotic evolution.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Minnesota-Duluth, Duluth, Minnesota 55812-2487, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Lindley
authors.forename: Tammy
authors.initials: T
authors.lastname: Laberge
authors.forename: Aaron
authors.initials: A
authors.lastname: Hall
authors.forename: David
authors.initials: D
authors.lastname: Hewett-Emmett
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Walsh
authors.forename: Paul M
authors.initials: PM
authors.lastname: Anderson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D015971:Gene Expression Regulation, Enzymologic; D008099:Liver / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D012965:Sodium Chloride / Q000378:metabolism; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics*
chemical_list: D029867:Xenopus Proteins; D012965:Sodium Chloride; D002222:Carbamoyl-Phosphate Synthase (Ammonia)