Regulation of
            <i>Escherichia coli</i>
            Glutamine Synthetase

Rhee, Sang Youl; Chock, P. Boon; Er, Stadtman

doi:10.1002/9780470123089.ch2

Cited by 44 publications

(39 citation statements)

References 108 publications

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“…We reported significant differences in heat stability and catalytic properties between maize GS1a and GS1d (7). Under low concentrations of divalent metal cations and high temperature, GS1d is easily inactivated as is the case for the bacterial GS from E. coli (3,24). This inactivation is caused by dissociation of the oligomeric assembly of the enzyme (3,7,24).…”

Section: Resultsmentioning

confidence: 96%

“…Overall Structure-Three different crystal forms of maize GS1a in complex with ADP and glutamate analogues were prepared in the presence of Mn 2ϩ , a divalent cation essential for GS activity (3). Substrate combinations were ADP and MetSox-P (18) (ADP/MetSox-P/Mn), AMPPNP and MetSox (AMPPNP/MetSox/Mn), and ADP and PPT-P (19) (ADP/PPT-P/Mn).…”

Section: Resultsmentioning

confidence: 99%

“…Under low concentrations of divalent metal cations and high temperature, GS1d is easily inactivated as is the case for the bacterial GS from E. coli (3,24). This inactivation is caused by dissociation of the oligomeric assembly of the enzyme (3,7,24). Even under such conditions, the activity and oligomeric structure of GS1a remains unchanged (7).…”

Section: Resultsmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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Atomic Structure of Plant Glutamine Synthetase

Unno

Uchida

Sugawara

et al. 2006

Journal of Biological Chemistry

138

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: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Atomic Structure of Plant Glutamine Synthetase

Unno

Uchida

Sugawara

et al. 2006

Journal of Biological Chemistry

138

195

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“…Also, an enzyme could be activated through the covalent addition of UMP (uridylylation) using UTP as a donor. Uridylylation has been shown to modulate the binding properties of P II proteins in Escherichia coli (Rhee et al 1989). Second, UTP may stimulate degradation by directly modifying RNAs, thus triggering their rapid turnover.…”

Section: Introductionmentioning

confidence: 99%

UTP-dependent turnover of Trypanosoma brucei mitochondrial mRNA requires UTP polymerization and involves the RET1 TUTase

Ryan¹,

Read²

2005

RNA

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Trypanosoma brucei mitochondria possess a unique RNA decay pathway in which rapid degradation of polyadenylated mRNAs is dependent on the addition of UTP, as measured by in organello pulse chase assays. To determine the mechanism by which UTP stimulates the degradation of polyadenylated RNAs, we performed in organello pulse chase assays under different conditions. Treatment of mitochondria with proteinase K revealed that UTP does not act through a receptor on the surface of the mitochondria. To determine if the UTP-stimulated RNA decay pathway is triggered by the mitochondrial energy state or ATP:UTP ratio, increasing ATP was added to a constant amount of UTP during the chase period of the assay. Results indicate that rapid turnover is responsive to UTP and not the ATP:UTP ratio. Experiments using UTP analogs demonstrate that UTP polymerization into RNAs is necessary for UTP-dependent degradation. Furthermore, experiments performed with RNAi cells indicate that the RET1 terminal uridylyl transferase (TUTase) is required for UTP-dependent decay of polyadenylated RNAs. Overall, these results show that degradation of polyadenylated RNAs in T. brucei mitochondria can occur through a unique mechanism that requires the polymerization of UTP into RNAs, presumably by the RET1 TUTase.

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Extending the diffraction limit of protein crystals: The example of glutamine synthetase from Salmonella typhimurium in the presence of its cofactor ATP

1993

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Glutamine synthetase (GS) plays a central role in cellular nitrogen metabolism in bacteria, catalyzing the ATPdependent condensation of ammonia with glutamate to yield glutamine in the presence of divalent cations. GS is regulated by product feedback, by oxidative modification, and by adenylylation (Rhee et al., 1989). The 3.5-A structure of completely unadenylylated GS was determined by Almassy et al. (1986) and refined by Yamashita et al. (1989). To improve the atomic model, and our understanding of the regulation and reaction mechanism, it has been necessary to grow GS crystals that diffract to higher resolution. We find that the cofactor ATP affects the size, growth rate, and diffraction quality of GS crystals.Two crystal forms grown in different concentrations of ATP or the reaction products ADP and Pi are found to have distinct morphologies, stabilities, space groups, and resolution limits. Form XVI crystals, grown at high ATP concentration (greater than 500 pM), grow to greater than 1 mm, belong to space group C222, and have unit-cell constants a = 235.1 A , b = 138.7 A , and c = 205.6 A.They diffract to no better than 3.2 A resolution and have a short lifetime in the X-ray beam. These crystals tend to redissolve.Form XIV crystals are grown at low ATP concentrations (less than 200 pM). They are routinely 0.8 X 0.6 X 0.2 mm and belong to space group C2, with unit-cell dimensions a = 235.5 A , b = 134.5 A, c = 200.1 A , and / 3 = 102.8'. They diffract to 2.4 A resolution, are suitable for data collection, and are stable for at least 6 months. Both Form XIV and XVI crystals have been observed earlier (Heidner et al., 1978;Janson et al., 1984), and Form XIV crystals have been used to determine the GS structure at 3.5 A resolution. However, before we determined the importance of ATP, crystals grew irregularly, were rarely large enough for X-ray diffraction studies, and had limited resolution. The present study reveals that the ATP concentration is a crucial variable in obtaining large, better diffracting crystals.The two differences in the growth conditions between crystal Forms XIV and XVI are the concentrations of ATP and of spermine tetrahydrochloride. The ATP:GS monomer ratio is 0.5 in the best Form XIV crystals, and it is equal to or greater than 1 in Form XVI crystals.Two lines of evidence suggest that high ATP concentration makes GS more soluble, accounting for the redissolving of Form XVI crystals. The first is that increased concentrations of positively charged spermine tetrahydrochloride stabilize the growth of GS containing high ATP. This is presumably because of charge compensation. The other line of evidence is that addition of 2 mM ATP to crystallization drops dissolves Form XIV crystals. High ATP may change the packing of GS moIecules, either because of an additional ATP binding site on the GS monomer, or because of the added negative charges of ATP. Whether ATP actually alters the packing of GS molecules we will learn only when we determine the structure of Form XVI crystals.It may be significa...

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Regulation of Escherichia coli Glutamine Synthetase

Cited by 44 publications

References 108 publications

Atomic Structure of Plant Glutamine Synthetase

Atomic Structure of Plant Glutamine Synthetase

UTP-dependent turnover of Trypanosoma brucei mitochondrial mRNA requires UTP polymerization and involves the RET1 TUTase

Extending the diffraction limit of protein crystals: The example of glutamine synthetase from Salmonella typhimurium in the presence of its cofactor ATP

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