title: Glutamine Assimilation and Feedback Regulation of L-acetyl-N-glutamate Kinase Activity in Chlorella variabilis NC64A Results in Changes in Arginine Pools.
abstract: Glutamine is a metabolite of central importance in nitrogen metabolism of microorganisms and plants. The Chlorella PII signaling protein controls, in a glutamine-dependent manner, the key enzyme of the ornithine/arginine biosynthesis pathway, N-acetyl-L-glutamate kinase (NAGK) that leads to arginine formation. We provide evidence that glutamine promotes effective growth of C. variabilis strain NC64A. The present study shows that externally supplied glutamine directly influences the internal pool of arginine in NC64A. Glutamine synthetase (GS) catalyzes the ATP-dependent conversion of glutamate and ammonium to glutamine. The results of this study demonstrate that glutamine acts as a negative effector of GS activity. These data emphasize the importance of glutamine-dependent coupling of metabolism and signaling as components of an efficient pathway allowing the maintenance of metabolic homeostasis and sustaining growth of Chlorella.
authors.affiliation: Lab Adaptation in Microorganisms, Biological Faculty, Saint-Petersburg State University, Universitetskaya em. 7/9, 199034 Saint-Petersburg, Russia.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Minaeva
authors.affiliation: Interfaculty Institute for Microbiology and Infection Medicine, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Forchhammer
authors.affiliation: Lab Adaptation in Microorganisms, Biological Faculty, Saint-Petersburg State University, Universitetskaya em. 7/9, 199034 Saint-Petersburg, Russia. Electronic address: ermilova@bio.spbu.ru.
authors.forename: Elena
authors.initials: E
authors.lastname: Ermilova
mesh_terms: D020418:Algal Proteins / Q000235:genetics* / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D002708:Chlorella / Q000235:genetics / Q000502:physiology*; D005974:Glutamate-Ammonia Ligase / Q000235:genetics* / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D008969:Molecular Sequence Data; D051922:PII Nitrogen Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D017851:Phosphotransferases (Carboxyl Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D020539:Sequence Analysis, Protein; D015398:Signal Transduction
chemical_list: D020418:Algal Proteins; D051922:PII Nitrogen Regulatory Proteins; D005973:Glutamine; D001120:Arginine; D017851:Phosphotransferases (Carboxyl Group Acceptor); C018721:acetylglutamate kinase; D005974:Glutamate-Ammonia Ligase
keywords: Chlorella; PII protein; glutamine sensing; glutamine synthetase.