PMID:17419734

Citation	Jonsson, A, Teixeira, PF and Nordlund, S (2007) The activity of adenylyltransferase in Rhodospirillum rubrum is only affected by alpha-ketoglutarate and unmodified PII proteins, but not by glutamine, in vitro. FEBS J. 274:2449-60
Abstract	Ammonium assimilation is tightly regulated in nitrogen-fixing bacteria; the target of regulation is primarily the activity of the key enzyme glutamine synthetase that is regulated by reversible covalent modification by AMP groups in reactions catalysed by the bifunctional adenylyltransferase (ATase). The properties and regulation of ATase from Escherichia coli have been studied in great detail. We have investigated the regulation of ATase from Rhodospirillum rubrum, a photosynthetic nitrogen-fixing bacterium. In this diazotroph, nitrogenase is regulated at the metabolic level in addition to the transcriptional regulation operating in all diazotrophic bacteria, which makes understanding the regulatory features of nitrogen assimilation even more interesting. We show that in R. rubrum, in contrast to the E. coli system, ATase is primarily regulated by alpha-ketoglutarate and that glutamine has no effect on neither the adenylylation nor the deadenylylation of glutamine synthetase. Furthermore, the role of the regulatory P(II) proteins is only to stimulate the adenylylation reaction, as there is no effect on the reverse reaction. We propose that in R. rubrum and possibly other diazotrophs alpha-ketoglutarate plays the central role in the regulation of ATase and thus glutamine synthetase activity.
Links	PubMed Online version:10.1111/j.1742-4658.2007.05778.x
Keywords	Amino Acid Sequence; Escherichia coli/metabolism; Glutamate-Ammonia Ligase/isolation & purification; Glutamate-Ammonia Ligase/metabolism; Glutamine/pharmacology; Ketoglutaric Acids/metabolism; Ketoglutaric Acids/pharmacology; Molecular Sequence Data; Nucleotidyltransferases/metabolism; PII Nitrogen Regulatory Proteins/physiology; Rhodospirillum rubrum/enzymology; Sequence Alignment
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RHORT:GLNB		GO:0030234: enzyme regulator activity	ECO:0000314:		F		See figure 3 from the paper.	complete CACAO 3334
RHORT:GLNB	enables	GO:0030234: enzyme regulator activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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