Nitrogen assimilation and nitrogen control in cyanobacteria

2005 ◽  
Vol 33 (1) ◽  
pp. 164-167 ◽  
Author(s):  
E. Flores ◽  
A. Herrero
Keyword(s):  
Amino Acids ◽  
Nitrogen Assimilation ◽  
Urea Cycle ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Nitrogen Control ◽  
Filamentous Cyanobacteria ◽  
Signal Transduction Protein ◽  
Nitrite Reductases ◽  
Nitrate And Nitrite

Nitrogen sources commonly used by cyanobacteria include ammonium, nitrate, nitrite, urea and atmospheric N2, and some cyanobacteria can also assimilate arginine or glutamine. ABC (ATP-binding cassette)-type permeases are involved in the uptake of nitrate/nitrite, urea and most amino acids, whereas secondary transporters take up ammonium and, in some strains, nitrate/nitrite. In cyanobacteria, nitrate and nitrite reductases are ferredoxin-dependent enzymes, arginine is catabolized by a combination of the urea cycle and arginase pathway, and urea is degraded by a Ni2+-dependent urease. These pathways provide ammonium that is incorporated into carbon skeletons through the glutamine synthetase–glutamate synthase cycle, in which 2-oxoglutarate is the final nitrogen acceptor. The expression of many nitrogen assimilation genes is subjected to regulation being activated by the nitrogen-control transcription factor NtcA, which is autoregulatory and whose activity appears to be influenced by 2-oxoglutarate and the signal transduction protein PII. In some filamentous cyanobacteria, N2 fixation takes place in specialized cells called heterocysts that differentiate from vegetative cells in a process strictly controlled by NtcA.

scholarly journals Light-Independent Nitrogen Assimilation in Plant Leaves: Nitrate Incorporation into Glutamine, Glutamate, Aspartate, and Asparagine Traced by 15N

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1303
Author(s):  
Tadakatsu Yoneyama ◽  
Akira Suzuki
Keyword(s):  
Amino Acids ◽  
Nitrogen Assimilation ◽  
Nitrate Assimilation ◽  
Glutamate Synthase ◽  
Enzymatic Reactions ◽  
Nitrite Reductases ◽  
Leaf Tissues ◽  
Nitrate And Nitrite ◽  
Cellular Compartments ◽  
Donor System

Although the nitrate assimilation into amino acids in photosynthetic leaf tissues is active under the light, the studies during 1950s and 1970s in the dark nitrate assimilation provided fragmental and variable activities, and the mechanism of reductant supply to nitrate assimilation in darkness remained unclear. 15N tracing experiments unraveled the assimilatory mechanism of nitrogen from nitrate into amino acids in the light and in darkness by the reactions of nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, aspartate aminotransferase, and asparagine synthetase. Nitrogen assimilation in illuminated leaves and non-photosynthetic roots occurs either in the redundant way or in the specific manner regarding the isoforms of nitrogen assimilatory enzymes in their cellular compartments. The electron supplying systems necessary to the enzymatic reactions share in part a similar electron donor system at the expense of carbohydrates in both leaves and roots, but also distinct reducing systems regarding the reactions of Fd-nitrite reductase and Fd-glutamate synthase in the photosynthetic and non-photosynthetic organs.

Primary nitrogen assimilation in higher plants and its regulation

1994 ◽  
Vol 72 (6) ◽  
pp. 739-750 ◽  
Author(s):  
Ann Oaks
Keyword(s):  
Nitrogen Assimilation ◽  
Higher Plants ◽  
Nitrate Assimilation ◽  
Glutamate Synthase ◽  
Ammonium Assimilation ◽  
Cellular Organization ◽  
Nitrite Reductases ◽  
Leaf Tissues ◽  
Nitrate And Nitrite ◽  
Key Words Nitrate

Characteristics of the enzymes involved in the assimilation of NO3− and NH4+, in particular the nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, glutamate dehydrogenase, glutamate decarboxylase, and asparagine synthetase, are described. The cellular organization of these enzymes in root and leaf tissues are assessed in view of recent research developments that utilize various tissue blotting techniques. Regulation of nitrate assimilation is analyzed at the physiological, biochemical, and molecular levels. Key words: nitrate, ammonium, assimilation, regulation.

Ammonia Assimilation by Thiocapsa roseopersicina Grown on Various Nitrogen and Carbon/Electron Sources

1980 ◽  
Vol 35 (5-6) ◽  
pp. 439-444 ◽  
Author(s):  
Eckhard Bast
Keyword(s):  
Amino Acids ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Ammonia Assimilation ◽  
Synthetic Activity ◽  
Transferase Activity ◽  
Organic Substrates ◽  
Batch Cultures ◽  
Electron Sources ◽  
Thiocapsa Roseopersicina

Abstract Batch cultures of the phototrophic bacterium, Thiocapsa roseopersicina, were grown anaero­ bically in the light either on sulfide with various ammonia concentrations, N 2 or amino acids as nitrogen sources, or on several simple organic substrates in the absence of reduced sulfur com­ pounds using 6 mM NH4Cl as source of nitrogen. At high ammonia concentrations high activities of (NADPH-linked) glutamate dehydrogenase (GDH), but rather low transferase and no bio­ synthetic activity of glutamine synthetase (GS) were obtained, while under conditions of ammonia deficiency (growth with N 2 or glutamate) GDH activity was very low and both GS activities were strongly increased. Glutamate synthase (GOGAT) activity (NADH-dependent) showed little variation. These data indicate that at high NH+ concentrations ammonia is assimilated via GDH, under NHJ limitation, however, via the GS/GOGAT system. Glutamine as nitrogen source may be utilized via GOGAT as well as via an active glutaminase plus GDH. Ammonia, but not glutamine, seems to cause repression and inactivation of GS. Alanine and asparagine inactivate the enzyme inhibiting the biosynthetic, but not the transferase activity. These amino acids in part also influence the activities of GDH, GOGAT, malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICDH). Cultures grown on acetate or pyruvate instead of sulfide showed increased GDH activities and high GS transferase activities possibly reflecting an increase of intracellular a-ketoglutarate concentration. On malate or fructose also increased GS transferase activities, but rather low GDH activities were observed. High biosynthetic GS activities and elevated GOGAT activities were found only in fructose-grown cells. On the organic substrates the ICDH activities always were somewhat higher than after lithoautotrophic growth. With the exception of acetate, the MDH activities were considerably elevated, especially on pyruvate. The different pathways of ar-keto-glutarate formation and their influence on the enzymes of ammonia assimilation are discussed.

Nitrogen assimilation and regulation of nitrate and nitrite reductases in cultured Ipomoea cells

1977 ◽  
Vol 55 (12) ◽  
pp. 1557-1568 ◽  
Author(s):  
M. W. Zink ◽  
I. A. Veliky
Keyword(s):  
Nitrogen Source ◽  
Nitrogen Assimilation ◽  
Nitrate Assimilation ◽  
Time Interval ◽  
Low Level ◽  
Stages Of Growth ◽  
Nitrite Reductases ◽  
Nitrate And Nitrite ◽  
In Cells

Ipomoea cells grown in a medium containing ammonium and nitrate preferentially used ammonium during the initial stages of growth but in the later stages assimilated nitrate rapidly regardless of the presence or absence of ammonium. Cells grown on nitrate and maintained at pH 4.8 released ammonia into the medium, whereas when they were maintained at pH 6.5 they secreted nitrite. The enzymes of nitrate assimilation were inducible by nitrate and the activities changed considerably in response to nitrogen source. The addition of ammonium 3 days after inoculation to cells highly induced for the reductases did not result in the suppression of further synthesis of the enzymes. The levels of nitrate (EC 1.6.6.1) and nitrite (EC 1.6.6.4) reductases detected in cells grown on ammonium as the nitrogen source were about 25% and 66%, respectively, of the fully induced level. The addition of nitrate to ammonium-assimilating cells resulted in a low level of induction of both reductases. Addition of nitrite had no effect. With both ammonium and nitrate initially present in the medium, the ammonium was utilized quickly but no induction of the reductases was observed for 24 h. the time interval when the assimilation of nitrate was low. This was followed by the induction of the enzymes to a higher level than the activity in cultures of similar age that had been grown continually in nitrate, supplied at the same concentration. Thus, for nitrate and nitrite reductases, repression-like effects were produced by ammonium.

scholarly journals DIFFERENT NITRATE AND AMMONIUM LEVELS MEDIA ON CHANGES OF NITROGEN ASSIMILATION ENZYMES IN RICE

2021 ◽  
Vol 7 (1) ◽  
pp. 25-31
Author(s):  
Tri Handoyo ◽  
Laily Ilman Widuri ◽  
Didik Pudji Restanto
Keyword(s):  
Nitrogen Assimilation ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Nitrate Content ◽  
Limiting Factor ◽  
Rice Plants ◽  
Glutamine Synthase ◽  
N Assimilation ◽  
Rice Yields ◽  
Different Sources

Nitrogen (N) is an important nutrient for the growth and development of rice plants, required in large quantity and often limiting factor of rice yields. The research was to understand the different sources and levels of nitrogen in rice plant on the activity of N assimilation enzymes, including nitrate reductase (NR), glutamine synthase (GS) content, glutamate synthase (Gogat) content, content, ammonium (NH4+) and nitrate (NO3-) content on the leaves. Paddy (Ciherang variety) was grown in sand media containing Hoagland solution with different sources (ammonium and nitrate) and levels (0.4, 0.8, 1.6, 3.2, 6.4, and 12.8 mM) of nitrogen. Nitrogen assimilation was observed from leaves at one month of age. The NR activity increased on both Nitrogen sources, it was a higher activity in media contained nitrate. Also, the activity of GS showed higher in media contains nitrate, but its activity was decreased after application 1.6 mM of nitrate and 3.2 mM of ammonium. Western blot analysis of GS1 and GS2 showed that the band pattern of protein was similar to these enzyme activities. Nitrate content in leaves gradually increased in both sources of nitrogen and higher than 3.2 mM ammonium application caused an increase in ammonium content in leaves, but the nitrate content decreased. This research resulted that the available source of N for rice was in nitrate form, easily by the rice plants during the growth stage.

scholarly journals DNA Microarray-Based Identification of Genes Regulated by NtrC in Bradyrhizobium japonicum

2015 ◽  
Vol 81 (16) ◽  
pp. 5299-5308 ◽  
Author(s):  
William L. Franck ◽  
Jing Qiu ◽  
Hae-In Lee ◽  
Woo-Suk Chang ◽  
Gary Stacey
Keyword(s):  
Nitrite Reductase ◽  
Bradyrhizobium Japonicum ◽  
Mutational Analysis ◽  
Transcriptional Profiling ◽  
Glutamate Synthase ◽  
Nitrogen Sources ◽  
Gene Encoding ◽  
Content Type ◽  
Nitrogenous Compounds ◽  
Nitrate And Nitrite

ABSTRACTTheBradyrhizobium japonicumNtrBC two-component system is a critical regulator of cellular nitrogen metabolism, including the acquisition and catabolism of nitrogenous compounds. To better define the roles of this system, genome-wide transcriptional profiling was performed to identify the NtrC regulon during the response to nitrogen limitation. Upon cells perceiving low intracellular nitrogen, they stimulate the phosphorylation of NtrC, which induces genes responsible for alteration of the core glutamine synthetase/glutamate synthase nitrogen assimilation pathway, including the genes for the glutamine synthetases and PII proteins. In addition, genes responsible for the import and utilization of multiple nitrogen sources, specifically nitrate and nitrite, were upregulated by NtrC activation. Mutational analysis of a candidate nitrite reductase revealed a role for NtrC in regulating the assimilation of nitrite, since mutations in bothntrCand the gene encoding the candidate nitrite reductase abolished the ability to grow on nitrite as a sole nitrogen source.

Nitrogen metabolism and chloramphenicol production in Streptomyces venezuelae

1983 ◽  
Vol 29 (12) ◽  
pp. 1706-1714 ◽  
Author(s):  
S. Shapiro ◽  
L. C. Vining
Keyword(s):  
Growth Rate ◽  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Nitrogen Assimilation ◽  
Glutamate Synthase ◽  
Biomass Accumulation ◽  
Nitrogen Sources ◽  
Ph Control ◽  
Ammonium Nitrogen ◽  
Streptomyces Venezuelae

The relationship between chloramphenicol production and nitrogen metabolism in Streptomyces venezuelae was examined in stirred jar cultures under pH control. Nitrogen sources that supported rapid biomass accumulation gave low rates of antibiotic synthesis during growth. This was consistent with a general incompatibility between fast growth and high yields of chloramphenicol. In media where the growth rate was reduced below the attainable maximum by the rate at which nitrogen could be assimilated, chloramphenicol production was associated with biomass accumulation. Enzymes that are potentially associated with nitrogen assimilation pathways were assayed in cultures supplied with nitrogen sources supporting markedly different growth rates. The results indicated mat glutamine synthetase and alanine dehydrogenase levels were relatively insensitive to changes in growth rate and nitrogen source depletion. Glutamate dehydrogenase and glutamate synthase, on the other hand, showed high activity in cultures assimilating ammonium nitrogen and markedly decreased activity with poorer nitrogen sources or when ammonium was depleted. If chloramphenicol biosynthesis is coordinately controlled by mechanisms that regulate nitrogen assimilation, glutamate synthase and glutamate dehydrogenase are the most likely enzymes that manifest the regulatory linkage.

scholarly journals Nitrogen Availability Affects the Metabolic Profile in Cyanobacteria

Metabolites ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 867
Author(s):  
Kosuke Inabe ◽  
Ayaka Miichi ◽  
Mami Matsuda ◽  
Takanobu Yoshida ◽  
Yuichi Kato ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nitrogen Assimilation ◽  
Nitrogen Availability ◽  
Nitrogen Sources ◽  
Tca Cycle ◽  
Metabolome Analysis ◽  
Rate Analysis ◽  
Genetic Responses ◽  
Synechocystis Sp ◽  
Pcc 6803

Nitrogen is essential for the biosynthesis of various molecules in cells, such as amino acids and nucleotides, as well as several types of lipids and sugars. Cyanobacteria can assimilate several forms of nitrogen, including nitrate, ammonium, and urea, and the physiological and genetic responses to these nitrogen sources have been studied previously. However, the metabolic changes in cyanobacteria caused by different nitrogen sources have not yet been characterized. This study aimed to elucidate the influence of nitrate and ammonium on the metabolic profiles of the cyanobacterium Synechocystis sp. strain PCC 6803. When supplemented with NaNO3 or NH4Cl as the nitrogen source, Synechocystis sp. PCC 6803 grew faster in NH4Cl medium than in NaNO3 medium. Metabolome analysis indicated that some metabolites in the CBB cycle, glycolysis, and TCA cycle, and amino acids were more abundant when grown in NH4Cl medium than NaNO3 medium. 15N turnover rate analysis revealed that the nitrogen assimilation rate in NH4Cl medium was higher than in NaNO3 medium. These results indicate that the mechanism of nitrogen assimilation in the GS-GOGAT cycle differs between NaNO3 and NH4Cl. We conclude that the amounts and biosynthetic rate of cyanobacterial metabolites varies depending on the type of nitrogen.

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