title: Molecular characterization of carbamoyl-phosphate synthetase (CPS1) deficiency using human recombinant CPS1 as a key tool.
abstract: The urea cycle disease carbamoyl-phosphate synthetase deficiency (CPS1D) has been associated with many mutations in the CPS1 gene [Häberle et al., 2011. Hum Mutat 32:579-589]. The disease-causing potential of most of these mutations is unclear. To test the mutations effects, we have developed a system for recombinant expression, mutagenesis, and purification of human carbamoyl-phosphate synthetase 1 (CPS1), a very large, complex, and fastidious enzyme. The kinetic and molecular properties of recombinant CPS1 are essentially the same as for natural human CPS1. Glycerol partially replaces the essential activator N-acetyl-l-glutamate (NAG), opening possibilities for treating CPS1D due to NAG site defects. The value of our expression system for elucidating the effects of mutations is demonstrated with eight clinical CPS1 mutations. Five of these mutations decreased enzyme stability, two mutations drastically hampered catalysis, and one vastly impaired NAG activation. In contrast, the polymorphisms p.Thr344Ala and p.Gly1376Ser had no detectable effects. Site-limited proteolysis proved the correctness of the working model for the human CPS1 domain architecture generally used for rationalizing the mutations effects. NAG and its analogue and orphan drug N-carbamoyl-l-glutamate, protected human CPS1 against proteolytic and thermal inactivation in the presence of MgATP, raising hopes of treating CPS1D by chemical chaperoning with N-carbamoyl-l-glutamate.
authors: Instituto de Biomedicina de Valencia, IBV-CSIC, Valencia, Spain.
authors: Carmen
authors: C
authors: Diez-Fernandez
authors: Ana I
authors: AI
authors: Martínez
authors: Satu
authors: S
authors: Pekkala
authors: Belén
authors: B
authors: Barcelona
authors: Isabel
authors: I
authors: Pérez-Arellano
authors: Ana María
authors: AM
authors: Guadalajara
authors: Marshall
authors: M
authors: Summar
authors: Javier
authors: J
authors: Cervera
authors: Vicente
authors: V
authors: Rubio
mesh_terms: D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D020165:Carbamoyl-Phosphate Synthase I Deficiency Disease / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D006801:Humans; D016296:Mutagenesis; D020125:Mutation, Missense; D011110:Polymorphism, Genetic; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D002222:Carbamoyl-Phosphate Synthase (Ammonia)
keywords: CPS1 deficiency; carbamylglutamate; hyperammonemia; urea cycle