title: Structure of human carbamoyl phosphate synthetase: deciphering the on/off switch of human ureagenesis.
abstract: Human carbamoyl phosphate synthetase (CPS1), a 1500-residue multidomain enzyme, catalyzes the first step of ammonia detoxification to urea requiring N-acetyl-L-glutamate (NAG) as essential activator to prevent ammonia/amino acids depletion. Here we present the crystal structures of CPS1 in the absence and in the presence of NAG, clarifying the on/off-switching of the urea cycle by NAG. By binding at the C-terminal domain of CPS1, NAG triggers long-range conformational changes affecting the two distant phosphorylation domains. These changes, concerted with the binding of nucleotides, result in a dramatic remodeling that stabilizes the catalytically competent conformation and the building of the ~35 Å-long tunnel that allows migration of the carbamate intermediate from its site of formation to the second phosphorylation site, where carbamoyl phosphate is produced. These structures allow rationalizing the effects of mutations found in patients with CPS1 deficiency (presenting hyperammonemia, mental retardation and even death), as exemplified here for some mutations.
authors.affiliation: Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC), Jaime Roig 11, 46010 Valencia, Spain.|Group 739, Centro de Investigación Biomédica en Red Sobre Enfermedades Raras del Instituto de Salud Carlos III (CIBERER-ISCIII), Jaime Roig 11, 46010 Valencia, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: de Cima
authors.affiliation: Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC), Jaime Roig 11, 46010 Valencia, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Polo
authors.affiliation: Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC), Jaime Roig 11, 46010 Valencia, Spain.|Centro de Investigación Príncipe Felipe, Eduardo Primo Yúfera 3, 46012 Valencia, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Díez-Fernández
authors.affiliation: Centro de Investigación Príncipe Felipe, Eduardo Primo Yúfera 3, 46012 Valencia, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Martínez
authors.affiliation: Group 739, Centro de Investigación Biomédica en Red Sobre Enfermedades Raras del Instituto de Salud Carlos III (CIBERER-ISCIII), Jaime Roig 11, 46010 Valencia, Spain.|Centro de Investigación Príncipe Felipe, Eduardo Primo Yúfera 3, 46012 Valencia, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Cervera
authors.affiliation: Instituto de Biología Molecular de Barcelona del Consejo Superior de Investigaciones Científicas (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10, 08028 Barcelona, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fita
authors.affiliation: Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC), Jaime Roig 11, 46010 Valencia, Spain.|Group 739, Centro de Investigación Biomédica en Red Sobre Enfermedades Raras del Instituto de Salud Carlos III (CIBERER-ISCIII), Jaime Roig 11, 46010 Valencia, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Rubio
mesh_terms: D020816:Amino Acid Motifs; D000641:Ammonia / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D016367:Baculoviridae / Q000235:genetics / Q000378:metabolism; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020165:Carbamoyl-Phosphate Synthase I Deficiency Disease / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D002221:Carbamyl Phosphate / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D015870:Gene Expression; D005971:Glutamates / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D061987:Sf9 Cells; D018411:Spodoptera; D013379:Substrate Specificity; D014508:Urea / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005971:Glutamates; D011994:Recombinant Proteins; D002221:Carbamyl Phosphate; D000641:Ammonia; D014508:Urea; D002222:Carbamoyl-Phosphate Synthase (Ammonia); C016195:N-acetylglutamic acid