The regulation of Escherichia coli glutamine synthetase revisited: role of 2-ketoglutarate in the regulation of glutamine synthetase adenylylation state. 1998

P Jiang, and J A Peliska, and A J Ninfa
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor 48109-0606, USA.

The regulation of Escherichia coli glutamine synthetase (GS) by reversible adenylylation has provided one of the classical paradigms for signal transduction by cyclic cascades. Yet, many mechanistic features of this regulation remain to be elucidated. We examined the regulation of GS adenylylation state in a reconstituted system containing GS, adenylyltransferase (ATase), the PII signal transduction protein that controls ATase, and the uridylyltransferase/uridylyl-removing enzyme (UTase/UR), which has a role in regulating PII. In this reconstituted bicyclic cascade system, the adenylylation state of GS was regulated reciprocally by the small molecule effectors 2-ketoglutarate and glutamine at physiological effector concentrations. By examination of the individual regulatory monocycles and comparison to the bicyclic system and existing data, we could deduce that the only sensors of 2-ketoglutarate were PII and PII-UMP. At physiological conditions, we observed that the main role of 2-ketoglutarate in bringing about the deadenylylation of GS was to inhibit GS adenylylation, and this was due to the allosteric regulation of PII activity. Glutamine acted as an allosteric regulator of both ATase and UTase/UR. We also compared the regulation of GS adenylylation state to the regulation of phosphorylation state of the transcription factor NRI (NtrC) in a reconstituted bicyclic system containing NRI, the bifunctional kinase/phosphatase NRII (NtrB), PII, and the UTase/UR. This comparison indicated that, at a fixed 2-ketoglutarate concentration, the regulation of GS adenylylation state by glutamine was sharper and occurred at a higher concentration than did the regulation of NRI phosphorylation. The possible biological implications of this regulatory arrangement are discussed.

UI MeSH Term Description Entries
D007656 Ketoglutaric Acids A family of compounds containing an oxo group with the general structure of 1,5-pentanedioic acid. (From Lehninger, Principles of Biochemistry, 1982, p442) Oxoglutarates,2-Ketoglutarate,2-Ketoglutaric Acid,2-Oxoglutarate,2-Oxoglutaric Acid,Calcium Ketoglutarate,Calcium alpha-Ketoglutarate,Ketoglutaric Acid,Oxogluric Acid,alpha-Ketoglutarate,alpha-Ketoglutaric Acid,alpha-Ketoglutaric Acid, Calcium Salt (2:1),alpha-Ketoglutaric Acid, Diammonium Salt,alpha-Ketoglutaric Acid, Dipotassium Salt,alpha-Ketoglutaric Acid, Disodium Salt,alpha-Ketoglutaric Acid, Monopotassium Salt,alpha-Ketoglutaric Acid, Monosodium Salt,alpha-Ketoglutaric Acid, Potassium Salt,alpha-Ketoglutaric Acid, Sodium Salt,alpha-Oxoglutarate,2 Ketoglutarate,2 Ketoglutaric Acid,2 Oxoglutarate,2 Oxoglutaric Acid,Calcium alpha Ketoglutarate,alpha Ketoglutarate,alpha Ketoglutaric Acid,alpha Ketoglutaric Acid, Diammonium Salt,alpha Ketoglutaric Acid, Dipotassium Salt,alpha Ketoglutaric Acid, Disodium Salt,alpha Ketoglutaric Acid, Monopotassium Salt,alpha Ketoglutaric Acid, Monosodium Salt,alpha Ketoglutaric Acid, Potassium Salt,alpha Ketoglutaric Acid, Sodium Salt,alpha Oxoglutarate,alpha-Ketoglutarate, Calcium
D009612 Nicotinamide-Nucleotide Adenylyltransferase An enzyme that catalyzes reversibly the transfer of the adenylyl moiety of ATP to the phosphoryl group of NMN to form NAD+ and pyrophosphate. The enzyme is found predominantly in the nuclei and catalyzes the final reaction in the major pathway for the biosynthesis of NAD in mammals. NAD Pyrophosphorylase,NMN Adenylyltransferase,Nicotinamide Mononucleotide Adenylyltransferase,ATP-NMN Adenylyltransferase,ATP NMN Adenylyltransferase,Adenylyltransferase, ATP-NMN,Adenylyltransferase, NMN,Adenylyltransferase, Nicotinamide Mononucleotide,Adenylyltransferase, Nicotinamide-Nucleotide,Mononucleotide Adenylyltransferase, Nicotinamide,Nicotinamide Nucleotide Adenylyltransferase,Pyrophosphorylase, NAD
D009713 Nucleotidyltransferases A class of enzymes that transfers nucleotidyl residues. EC 2.7.7. Nucleotidyltransferase
D010766 Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Phosphorylations
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005973 Glutamine A non-essential amino acid present abundantly throughout the body and is involved in many metabolic processes. It is synthesized from GLUTAMIC ACID and AMMONIA. It is the principal carrier of NITROGEN in the body and is an important energy source for many cells. D-Glutamine,L-Glutamine,D Glutamine,L Glutamine
D005974 Glutamate-Ammonia Ligase An enzyme that catalyzes the conversion of ATP, L-glutamate, and NH3 to ADP, orthophosphate, and L-glutamine. It also acts more slowly on 4-methylene-L-glutamate. (From Enzyme Nomenclature, 1992) EC 6.3.1.2. Glutamine Synthetase,Glutamate Ammonia Ligase (ADP),Glutamate Ammonia Ligase,Ligase, Glutamate-Ammonia,Synthetase, Glutamine
D000255 Adenosine Triphosphate An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter. ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D014542 Uridine Monophosphate 5'-Uridylic acid. A uracil nucleotide containing one phosphate group esterified to the sugar moiety in the 2', 3' or 5' position. UMP,Uridylic Acid,Uridine 5'-Monophosphate,Uridylic Acids,5'-Monophosphate, Uridine,Acid, Uridylic,Acids, Uridylic,Monophosphate, Uridine,Uridine 5' Monophosphate

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