Covalent modification of bacterial glutamine synthetase: physiological significance

Kustu, Sydney; Hirschman, Jodi E.; Burton, Doris; Jelesko, John G.; Meeks, John C.

doi:10.1007/bf00330979

Cited by 79 publications

(90 citation statements)

References 37 publications

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“…Consistent with the conclusion that the gln-71 mutation is in the glnE gene is the fact that the poor growth phenotype of MV71 and MV72 on BSN medium is similar to that shown by glnE mutants of Salmonella typhimurium (Kustu et al, 1984). Poor growth by these mutants was attributed to a deficiency of glutamate due to its hyperconversion to glutamine.…”

Section: The Gln-71 Mutation Is Probably Located In the Glne Genesupporting

confidence: 72%

Lethality of glnD null mutations in Azotobacter vinelandii is suppressible by prevention of glutamine synthetase adenylylation

Colnaghi

Rudnick

et al. 2001

Microbiology

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GlnD is a pivotal protein in sensing intracellular levels of fixed nitrogen and has been best studied in enteric bacteria, where it reversibly uridylylates two related proteins, PII and GlnK. The uridylylation state of these proteins determines the activities of glutamine synthetase (GS) and NtrC. Results presented here demonstrate that glnD is an essential gene in Azotobacter vinelandii. Null glnD mutations were introduced into the A. vinelandii genome, but none could be stably maintained unless a second mutation was present that resulted in unregulated activity of GS. One mutation, gln-71, occurred spontaneously to give strain MV71, which failed to uridylylate the GlnK protein. The second, created by design, was glnAY407F (MV75), altering the adenylylation site of GS. The gln-71 mutation is probably located in glnE, encoding adenylyltransferase, because introducing the Escherichia coli glnE gene into MV72, a glnD M derivative of MV71, restored the regulation of GS activity. GlnK-UMP is therefore apparently required for GS to be sufficiently deadenylylated in A. vinelandii for growth to occur. The ∆glnD GS c isolates were Nif N , which could be corrected by introducing a nifL mutation, confirming a role for GlnD in mediating nif gene regulation via some aspect of the NifL/NifA interaction. MV71 was unexpectedly NtrC M , suggesting that A. vinelandii NtrC activity might be regulated differently than in enteric organisms.

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Section: The Gln-71 Mutation Is Probably Located In the Glne Genesupporting

confidence: 72%

Lethality of glnD null mutations in Azotobacter vinelandii is suppressible by prevention of glutamine synthetase adenylylation

Colnaghi

Rudnick

et al. 2001

Microbiology

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“…Indeed, similar alterations in nitrogen metabolism are observed in the B. subtilis glnA186 mutant and in strains of S. typhimurium that contain mutations in glnE, the gene encoding GS adenylyltransferase (36). Both the B. subtilis glnA186 and the S. typhimurium glnE mutant strains excrete glutamine.…”

Section: Discussionmentioning

confidence: 69%

A Feedback-resistant Mutant of Bacillus subtilis Glutamine Synthetase with Pleiotropic Defects in Nitrogen-regulated Gene Expression

Wray

Fisher

2005

Journal of Biological Chemistry

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The Bacillus subtilis TnrA transcription factor regulates gene expression during nitrogen-limited growth. When cells are grown with excess nitrogen, feedback-inhibited glutamine synthetase forms a protein-protein complex with TnrA and prevents TnrA from binding to DNA. A mutation in glutamine synthetase with a phenylalanine replacement at the Ser-186 residue (S186F) was isolated by screening for B. subtilis mutants with constitutive TnrA activity. Although S186F glutamine synthetase has kinetic properties that are similar to the wild-type protein, the S186F enzyme is resistant to feedback inhibition by glutamine and AMP. Ligand binding experiments revealed that the S186F protein had a lower affinity for glutamine and AMP than the wild-type enzyme. S186F glutamine synthetase was defective in its ability to block DNA binding by TnrA in vitro. The properties of the feedback-resistant S186F mutant support the model in which the feedback-inhibited form of glutamine synthetase regulates TnrA activity in vivo.

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“…It was suggested that this drop was due to the transiently elevated activity of glutamine synthetase following the increased uptake of ammonium and that the ammonium-induced inactivation of glutamine synthetase by adenylylation is necessary to protect the cell from an unsustainable drain on the ATP pool (33,34). However, others have argued that the primary function of glutamine synthetase adenylylation is to protect the cellular glutamate pool and that other mechanisms exist to protect the ATP pool (35).…”

Section: -Og Atp and Adp Pools In A Glnamentioning

confidence: 99%

Control of AmtB-GlnK Complex Formation by Intracellular Levels of ATP, ADP, and 2-Oxoglutarate

Radchenko

Thornton

Merrick

2010

Journal of Biological Chemistry

127

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P II proteins are one of the most widespread families of signal transduction proteins in nature, being ubiquitous throughout bacteria, archaea, and plants. They play a major role in coordinating nitrogen metabolism by interacting with, and regulating the activities of, a variety of enzymes, transcription factors, and membrane transport proteins. The regulatory properties of P II proteins derive from their ability to bind three effectors: ATP, ADP, and 2-oxoglutarate. However, a clear model to integrate physiological changes with the consequential structural changes that mediate P II interaction with a target protein has so far not been developed. In this study, we analyzed the fluctuations in intracellular effector pools in Escherichia coli during association and dissociation of the P II protein GlnK with the ammonia channel AmtB. We determined that key features promoting AmtB-GlnK complex formation are the rapid drop in the 2-oxoglutarate pool upon ammonium influx and a simultaneous, but transient, change in the ATP/ADP ratio. We were also able to replicate AmtB-GlnK interactions in vitro using the same effector combinations that we observed in vivo. This comprehensive data set allows us to propose a model that explains the way in which interactions between GlnK and its effectors influence the conformation of GlnK and thereby regulate its interaction with AmtB.

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Covalent modification of bacterial glutamine synthetase: physiological significance

Cited by 79 publications

References 37 publications

Lethality of glnD null mutations in Azotobacter vinelandii is suppressible by prevention of glutamine synthetase adenylylation

Lethality of glnD null mutations in Azotobacter vinelandii is suppressible by prevention of glutamine synthetase adenylylation

A Feedback-resistant Mutant of Bacillus subtilis Glutamine Synthetase with Pleiotropic Defects in Nitrogen-regulated Gene Expression

Control of AmtB-GlnK Complex Formation by Intracellular Levels of ATP, ADP, and 2-Oxoglutarate

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