The three-dimensional structure of an eukaryotic glutamine synthetase: Functional implications of its oligomeric structure

Llorca, Óscar; Betti, Marco; González, José M.; Valencia, Alfonso; Márquez, Antonio J.; Valpuesta, José M.

doi:10.1016/j.jsb.2006.06.003

Cited by 60 publications

(61 citation statements)

References 45 publications

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“…GS2 is encoded by a single gene (Gln-2), whereas GS1 is encoded by a multigene family, suggesting a complex role of GS1 with respect to plant N assimilation (Rodriguez et al, 2012). Arabidopsis (Arabidopsis thaliana) has five isogenes for GS1 (Gln-1;1-5) and the active structure of GS1 consists of octameric oligomers (Llorca et al, 2006). In roots, the individual GS1 isoforms have specific localizations and expression patterns, as well as distinct kinetic properties with respect to ammonium and Glu (Guo et al, 2004;Ishiyama et al, 2004aIshiyama et al, , 2004bWang et al, 2013).…”

Section: Nitrate (Nomentioning

confidence: 99%

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

et al. 2016

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Cytosolic GS1 (Gln synthetase) is central for ammonium assimilation in plants. High ammonium treatment enhanced the expression of the GS1 isogene Gln-1;2 encoding a low-affinity high-capacity GS1 protein in Arabidopsis (Arabidopsis thaliana) shoots. Under the same conditions, the expression of the high-affinity low-capacity isoform Gln-1;1 was reduced. The expression of Gln-1;3 did not respond to ammonium treatment while Gln-1;4 and Gln-1;5 isogenes in all cases were expressed at a very low level. Gln-2 was highly expressed in shoots but only at a very low level in roots. To investigate the specific functions of the two isogenes Gln-1;1 and Gln-1;2 in shoots for ammonium detoxification, single and double knock-out mutants were grown under standard N supply or with high ammonium provision. Phenotypes of the single mutant gln1;1 were similar to the wild type, while growth of the gln1;2 single mutant and the gln1;1:gln1;2 double mutant was significantly impaired irrespective of N regime. GS1 activity was significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increased while that of Gln decreased, showing that Gln-1;2 was essential for ammonium assimilation and amino acid synthesis. We conclude that Gln-1;2 is the main isozyme contributing to shoot GS1 activity in vegetative growth stages and can be up-regulated to relieve ammonium toxicity. This reveals, to our knowledge, a novel shoot function of Gln-1;2 in Arabidopsis shoots.

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Section: Nitrate (Nomentioning

confidence: 99%

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

et al. 2016

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“…In fact, previous SEC and electron microscopy studies demonstrated that the GSs from Escherichia coli, Ruminococcus albus 8, Neurospora crassa, and the plant Phaseolus vulgaris are present in solution as both monomers and their requisite higher-order oligomers (D avila et al 1980;Denman and Wedler 1984;Amaya et al 2005;Llorca et al 2006). However, to assess the solution oligomeric status of the B. subtilis enzyme, we performed SEC studies.…”

Section: Structure Of the Gs-gln-tnra Complex: Mechanism Of Tnra Deacmentioning

confidence: 99%

Structures of regulatory machinery reveal novel molecular mechanisms controlling B. subtilis nitrogen homeostasis

et al. 2015

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All cells must sense and adapt to changing nutrient availability. However, detailed molecular mechanisms coordinating such regulatory pathways remain poorly understood. In Bacillus subtilis, nitrogen homeostasis is controlled by a unique circuitry composed of the regulator TnrA, which is deactivated by feedback-inhibited glutamine synthetase (GS) during nitrogen excess and stabilized by GlnK upon nitrogen depletion, and the repressor GlnR. Here we describe a complete molecular dissection of this network. TnrA and GlnR, the global nitrogen homeostatic transcription regulators, are revealed as founders of a new structural family of dimeric DNA-binding proteins with C-terminal, flexible, effector-binding sensors that modulate their dimerization. Remarkably, the TnrA sensor domains insert into GS intersubunit catalytic pores, destabilizing the TnrA dimer and causing an unprecedented GS dodecamer-to-tetradecamer conversion, which concomitantly deactivates GS. In contrast, each subunit of the GlnK trimer “templates” active TnrA dimers. Unlike TnrA, GlnR sensors mediate an autoinhibitory dimer-destabilizing interaction alleviated by GS, which acts as a GlnR chaperone. Thus, these studies unveil heretofore unseen mechanisms by which inducible sensor domains drive metabolic reprograming in the model Gram-positive bacterium B. subtilis.

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“…The analysis of protein structures is generally 2 Journal of Viruses [13][14][15], theoretical models [16][17][18][19], and protein engineering [20,21]. For in silico ligand designing to be an effective inhibitor, Rep protein of selected begomovirus strains (YP 003288785, YP 002004579, and YP 003288773), which is responsible for replication, was used.…”

Section: Introductionmentioning

confidence: 99%

Recognition of Errors in the Refinement and Validation of Three-Dimensional Structures of AC1 Proteins of Begomovirus Strains by Using ProSA-Web

2014

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The structural model of begomovirus AC1 protein is useful for understanding biological function at molecular level and docking study. For this study we have used the ProSA program (Protein Structure Analysis) tool to establish the structure prediction and modeling of protein. This tool was used for refinement and validation of experimental protein structures. Potential problems of protein structures based on energy plots are easily seen by ProSA and are displayed in a three-dimensional manner. In the present study we have selected different AC1 proteins of begomovirus strains (YP 003288785, YP 002004579, and YP 003288773) for structural analysis and display of energy plots that highlight potential problems spotted in protein structures. The 3D models of Rep proteins with recognized errors can be effectively used for in silico docking study for development of potential ligand molecules against begomovirus infection.

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The three-dimensional structure of an eukaryotic glutamine synthetase: Functional implications of its oligomeric structure

Cited by 60 publications

References 45 publications

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

Structures of regulatory machinery reveal novel molecular mechanisms controlling B. subtilis nitrogen homeostasis

Recognition of Errors in the Refinement and Validation of Three-Dimensional Structures of AC1 Proteins of Begomovirus Strains by Using ProSA-Web

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