The structures of cytosolic and plastid-located glutamine synthetases from<i>Medicago truncatula</i>reveal a common and dynamic architecture

Torreira, Eva; Seabra, Ana R.; Marriott, Helen M.; Zhou, Min; Llorca, Óscar; Robinson, Carol V.; Carvalho, Helena; Fernández‐Tornero, Carlos; Pereira, Pedro José Barbosa

doi:10.1107/s1399004713034718

Cited by 26 publications

(44 citation statements)

References 51 publications

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“…Amino acid positions altered by relaxed selection constraints did not include known ligand interacting sites (ATP, glutamate, ammonia, and metal coordination sites were evaluated according to [86]). However, few sequences were considerably truncated and lacked several ligand binding sites, namely: GS1_cs1, Lj0g3v0335159 and GLYMA02G41106; GS1cs2, Lj2g3v0658180; and GS2, Lj6g3v1953860.…”

Section: The Majority Of Positively Selected Gs and Pepc Genes Are Dumentioning

confidence: 99%

A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin (Lupinus angustifolius L.)

Czyż

Książkiewicz

Koczyk

et al. 2020

IJMS

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Narrow-leafed lupin (Lupinus angustifolius L.) has recently been supplied with advanced genomic resources and, as such, has become a well-known model for molecular evolutionary studies within the legume family—a group of plants able to fix nitrogen from the atmosphere. The phylogenetic position of lupins in Papilionoideae and their evolutionary distance to other higher plants facilitates the use of this model species to improve our knowledge on genes involved in nitrogen assimilation and primary metabolism, providing novel contributions to our understanding of the evolutionary history of legumes. In this study, we present a complex characterization of two narrow-leafed lupin gene families—glutamine synthetase (GS) and phosphoenolpyruvate carboxylase (PEPC). We combine a comparative analysis of gene structures and a synteny-based approach with phylogenetic reconstruction and reconciliation of the gene family and species history in order to examine events underlying the extant diversity of both families. Employing the available evidence, we show the impact of duplications on the initial complement of the analyzed gene families within the genistoid clade and posit that the function of duplicates has been largely retained. In terms of a broader perspective, our results concerning GS and PEPC gene families corroborate earlier findings pointing to key whole genome duplication/triplication event(s) affecting the genistoid lineage.

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Section: The Majority Of Positively Selected Gs and Pepc Genes Are Dumentioning

confidence: 99%

A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin (Lupinus angustifolius L.)

Czyż

Książkiewicz

Koczyk

et al. 2020

IJMS

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“…Determining the three-dimensional structures of closely related GS isoenzymes and their catalytic properties is critical to establish structure-function relationships. However, and in spite of the importance of GS in plants, the structure of the plant enzyme has only recently been elucidated ( Unno et al, 2006 ; Torreira et al, 2014 ). For a long time it was believed that eukaryotic GS had a octameric architecture, based on extrapolation from the best-studied prokaryotic enzymes ( Eisenberg et al, 1987 ).…”

Section: Dynamics Of Enzyme Catalysis Revealed By the Structure Analymentioning

confidence: 99%

“…For a long time it was believed that eukaryotic GS had a octameric architecture, based on extrapolation from the best-studied prokaryotic enzymes ( Eisenberg et al, 1987 ). The determination of the atomic structure of the cytosolic GS1a from maize (ZmGS1a) and M. truncatula (MtGS1a) by X-ray crystallography revealed a decameric organization ( Unno et al, 2006 ; Seabra et al, 2009 ; Torreira et al, 2014 ) that is common to the human and dog ( Krajewski et al, 2008 ) and also to the yeast enzymes ( He et al, 2009 ). Eukaryotic GS is arranged in two stacked (face-to-face) pentameric rings with extensive contacts established between subunits of the same ring and limited interactions with the subunits of the opposite ring.…”

Section: Dynamics Of Enzyme Catalysis Revealed By the Structure Analymentioning

confidence: 99%

“…Here, we highlight some interesting features related to the dynamics of enzyme catalysis revealed by the structural analysis of the cytosolic (MtGS1a) and plastid-located GSs (MtGS2a) from M. truncatula ( Torreira et al, 2014 ). The three-dimensional structure of unliganded MtGS1a was determined at 2.35 Ǻ resolution by X-ray crystallography (Figure 2 ; Seabra et al, 2009 ), and a comparison with the maize ortholog, whose structure was determined in complex with GS inhibitors ( Unno et al, 2006 ) revealed some critical differences: The Trp141–Gly152 surface segment displays a different arrangement in the two enzymes, resulting in a 15° rotation in the relative position of the two rings in the free MtGS1a enzyme, when compared to the inhibited maize enzyme, suggesting that substrate binding and release could be related to the rotation of the pentameric rings ( Torreira et al, 2014 ). The plastid-located MtGS2a is also a decamer composed of two superposed pentameric rings, as revealed by cryo-electron microscopy, but the association between the double-stacked rings appears to be more flexible than in MtGS1a ( Torreira et al, 2014 ; Figure 2 ).…”

Section: Dynamics Of Enzyme Catalysis Revealed By the Structure Analymentioning

confidence: 99%

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Glutamine synthetase in Medicago truncatula, unveiling new secrets of a very old enzyme

Seabra

Carvalho

2015

Front. Plant Sci.

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Glutamine synthetase (GS) catalyzes the first step at which nitrogen is brought into cellular metabolism and is also involved in the reassimilation of ammonium released by a number of metabolic pathways. Due to its unique position in plant nitrogen metabolism, GS plays essential roles in all aspects of plant development, from germination to senescence, and is a key component of nitrogen use efficiency (NUE) and plant yield. Understanding the mechanisms regulating GS activity is therefore of utmost importance and a great effort has been dedicated to understand how GS is regulated in different plant species. The present review summarizes exciting recent developments concerning the structure and regulation of GS isoenzymes, using the model legume Medicago truncatula. These include the understanding of the structural determinants of both the cytosolic and plastid located isoenzymes, the existence of a seed-specific GS gene unique to M. truncatula and closely related species and the discovery that GS isoenzymes are regulated by nitric oxide at the post-translational level. The data is discussed and integrated with the potential roles of the distinct GS isoenzymes within the whole plant context.

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“…GS in higher plants also exists as two distinct types, cytosolic GS (GS1) and plastidic GS (GS2), with different polypeptide sizes of 38–40 kDa and 42–45 kDa, respectively [15] . Plant GS1 and GS2 polypeptides assemble into decameric complexes to be active holoenzymes [16] , [17] . In this study, we found each of NiR, GS and GOGAT assembled into discrete protein complexes in the chloroplasts of spinach leaves, and the dissociation profile of these complexes varied in response to the changes in the stromal conditions.…”

Section: Introductionmentioning

confidence: 99%

Multiple Complexes of Nitrogen Assimilatory Enzymes in Spinach Chloroplasts: Possible Mechanisms for the Regulation of Enzyme Function

Kimata‐Ariga

Hase

2014

PLoS ONE

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Assimilation of nitrogen is an essential biological process for plant growth and productivity. Here we show that three chloroplast enzymes involved in nitrogen assimilation, glutamate synthase (GOGAT), nitrite reductase (NiR) and glutamine synthetase (GS), separately assemble into distinct protein complexes in spinach chloroplasts, as analyzed by western blots under blue native electrophoresis (BN-PAGE). GOGAT and NiR were present not only as monomers, but also as novel complexes with a discrete size (730 kDa) and multiple sizes (>120 kDa), respectively, in the stromal fraction of chloroplasts. These complexes showed the same mobility as each monomer on two-dimensional (2D) SDS-PAGE after BN-PAGE. The 730 kDa complex containing GOGAT dissociated into monomers, and multiple complexes of NiR reversibly converted into monomers, in response to the changes in the pH of the stromal solvent. On the other hand, the bands detected by anti-GS antibody were present not only in stroma as a conventional decameric holoenzyme complex of 420 kDa, but also in thylakoids as a novel complex of 560 kDa. The polypeptide in the 560 kDa complex showed slower mobility than that of the 420 kDa complex on the 2D SDS-PAGE, implying the assembly of distinct GS isoforms or a post-translational modification of the same GS protein. The function of these multiple complexes was evaluated by in-gel GS activity under native conditions and by the binding ability of NiR and GOGAT with their physiological electron donor, ferredoxin. The results indicate that these multiplicities in size and localization of the three nitrogen assimilatory enzymes may be involved in the physiological regulation of their enzyme function, in a similar way as recently described cases of carbon assimilatory enzymes.

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The structures of cytosolic and plastid-located glutamine synthetases fromMedicago truncatulareveal a common and dynamic architecture

Abstract: The experimental models of dicotyledonous cytoplasmic and plastid-located glutamine synthetases unveil a conserved eukaryotic-type decameric architecture, with subtle structural differences in M. truncatula isoenzymes that account for their distinct herbicide resistance.

Cited by 26 publications

References 51 publications

A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin (Lupinus angustifolius L.)

A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin (Lupinus angustifolius L.)

Glutamine synthetase in Medicago truncatula, unveiling new secrets of a very old enzyme

Multiple Complexes of Nitrogen Assimilatory Enzymes in Spinach Chloroplasts: Possible Mechanisms for the Regulation of Enzyme Function

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