title: Arginine and nitrogen storage.
abstract: When nitrogen is abundant, prokaryotic and eukaryotic oxygen-producing photosynthetic organisms store nitrogen as arginine, by relieving feedback inhibition of the arginine biosynthesis controlling enzyme, N-acetylglutamate kinase (NAGK). The signalling protein PII, an ancient and widely distributed nitrogen/carbon/ADP/ATP sensor, mediates feedback inhibition relief of NAGK by binding to this enzyme. PII phosphorylation or PII binding of ADP or 2-oxoglutarate prevents PII-NAGK complex formation. Crystal structures of NAGK, cyanobacterial and plant PII and corresponding PII-NAGK complexes have been recently determined. In these complexes, two polar PII trimers sandwich one ring-like NAGK hexamer. Each PII subunit contacts one NAGK subunit, triggering a symmetry-restricted narrowing of the NAGK ring, with concomitant adoption by the arginine sites of a low-affinity conformation.
authors.affiliation: Instituto de Biomedicina de Valencia-Consejo Superior de Investigaciones Cientificas (IBV-CSIC) and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Jaime Roig 11, Valencia 46010, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Llácer
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fita
authors.forename: Vicente
authors.initials: V
authors.lastname: Rubio
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism; D001120:Arginine / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009584:Nitrogen / Q000378:metabolism*; D017851:Phosphotransferases (Carboxyl Group Acceptor) / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D046940:Synechococcus / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; D001120:Arginine; D017851:Phosphotransferases (Carboxyl Group Acceptor); C018721:acetylglutamate kinase; D009584:Nitrogen