Biochemical Background and Compartmentalized Functions of Cytosolic Glutamine Synthetase for Active Ammonium Assimilation in Rice Roots

Ishiyama, Keiki; Inoue, Eri; Tabuchi, Mayumi; Yamaya, Tomoyuki; Takahashi, Hideki

doi:10.1093/pcp/pch190

Cited by 130 publications

(109 citation statements)

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“…The presence of such isoenzymes is considered to be crucial for efficient ammonia assimilation in response to variable internal and external environments (7,22,23). We reported significant differences in heat stability and catalytic properties between maize GS1a and GS1d (7).…”

Section: Resultsmentioning

confidence: 84%

Atomic Structure of Plant Glutamine Synthetase

Unno

Uchida

Sugawara

et al. 2006

Journal of Biological Chemistry

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137

195

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Plants provide nourishment for animals and other heterotrophs as the sole primary producer in the food chain. Glutamine synthetase (GS), one of the essential enzymes for plant autotrophy catalyzes the incorporation of ammonia into glutamate to generate glutamine with concomitant hydrolysis of ATP, and plays a crucial role in the assimilation and re-assimilation of ammonia derived from a wide variety of metabolic processes during plant growth and development. Elucidation of the atomic structure of higher plant GS is important to understand its detailed reaction mechanism and to obtain further insight into plant productivity and agronomical utility. Here we report the first crystal structures of maize (Zea mays L.) GS. The structure reveals a unique decameric structure that differs significantly from the bacterial GS structure. Higher plants have several isoenzymes of GS differing in heat stability and catalytic properties for efficient responses to variation in the environment and nutrition. A key residue responsible for the heat stability was found to be Ile-161 in GS1a. The three structures in complex with substrate analogues, including phosphinothricin, a widely used herbicide, lead us to propose a mechanism for the transfer of phosphate from ATP to glutamate and to interpret the inhibitory action of phosphinothricin as a guide for the development of new potential herbicides.Inorganic nitrogen is an essential, often limiting nutrient for plant growth and development. In most natural soils, nitrate is the major form of inorganic nitrogen. After uptake of nitrate, plants first reduce it to ammonia, and then assimilate it into an organic compound as an amide moiety of glutamine. Because glutamine synthetase (GS) 7 catalyzes the very step of assimilation of inorganic nitrogen and because the amide moiety of glutamine is utilized as the donor of amino residue to synthesize a number of essential metabolites such as amino acids, nucleic acids, and amino sugars, glutamine synthesis by plant GS is the cornerstone of plant productivity and thus nitrogen nourishment of all animals on the Earth. For this reason, the importance of plant GS is comparable with that of ribulose-1,5-bisphosphate carboxylase/oxygenase, the carbon dioxide assimilating enzyme (1).Comparison of the primary structures of GSs from prokaryotes and eukaryotes, results in plant GS being categorized as type II, this type commonly occurring in eukaryotes including animals (2). In contrast, type I GS is widely found in prokaryotes (2). The regulatory mechanisms of type I GS activity such as adenylylation and metabolite feedback have been thoroughly characterized (3). The crystal structures of GS from Mycobacterium tuberculosis (4) and Salmonella typhimurium (5) have been determined and the proteins shown to be dodecameric, with each dodecamer being composed of one identical subunit with a molecular mass of about 52 kDa. Types I and II GSs are thought to share a common ancestor but to have diverged into the two types at a very early stage during molecula...

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Section: Resultsmentioning

confidence: 84%

Atomic Structure of Plant Glutamine Synthetase

Unno

Uchida

Sugawara

et al. 2006

Journal of Biological Chemistry

Self Cite

137

195

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“…Glutamine synthetase is a central enzyme in the nitrogen metabolism of higher plant (Lightfoot et al, 1988) and plays a role in the primary assimilation of ammonia (Hirel and Gadal, 1980;Tsai et al, 2003), the re-assimilation of ammonia released from the photorespiratory nitrogen cycle, and the catabolism of nitrogenous storage and transport of nitrogenous compounds (Lea and Mifl in, 2003;McNally et al, 1983). Moreover, rice plants in paddy fi elds utilize ammonium as a major nitrogen source (Ishiyama et al, 2004). Therefore, nitrogen content of rice plants is greatly related to glutamine synthetase activity.…”

Section: Resultsmentioning

confidence: 99%

Yield Component Differences between Direct-Seeded and Transplanted Super Hybrid Rice

Huang

Zou

Jiang

et al. 2011

Plant Production Science

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“…OsGS1;1 and OsGS1;2 both showed a high substrate affinity for ammonium and were induced by ammonium within the central cylinder of rice-elongating zone [58]. OsGS1;1 was constitutively expressed , with higher expression profile in leaf blade and participated in rice normal growth and grain filling [59,60].…”

Section: Nitrogen Assimilationmentioning

confidence: 99%

Nitrogen Use Efficiency in Rice

Huang¹,

Zhao²,

Zhang³

et al. 2018

Nitrogen in Agriculture - Updates

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Food security is a major global issue because of the growing population and decreasing land area. Rice (Oryza sativa L.) is the most important staple cereal crop in the world. Application of nitrogen (N) fertilizer has improved crop yield in the world during the past five decades but with considerable negative impacts on the environment. New solutions are therefore urgently needed to simultaneously increase yields while maintaining or preferably decreasing applied N to maximize the nitrogen use efficiency (NUE) of crops. Plant NUE is inherently complex with each step (including N uptake, translocation, assimilation, and remobilization) governed by multiple interacting genetic and environmental factors. Based on the current knowledge, we propose some possible approaches enhancing NUE, by molecular manipulation selecting candidate genes and agricultural integrated management practices for NUE improvement. Developing an integrated research program combining approaches, mainly based on whole-plant physiology, quantitative genetics, forward and reverse genetics, and agronomy approaches to improve NUE, is a major objective in the future.

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Biochemical Background and Compartmentalized Functions of Cytosolic Glutamine Synthetase for Active Ammonium Assimilation in Rice Roots

Cited by 130 publications

References 42 publications

Atomic Structure of Plant Glutamine Synthetase

Atomic Structure of Plant Glutamine Synthetase

Yield Component Differences between Direct-Seeded and Transplanted Super Hybrid Rice

Nitrogen Use Efficiency in Rice

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