scholarly journals Nitrogen Metabolism of Lemna minor. I. Growth, Nitrogen Sources and Amino Acid Inhibition

1969 ◽  
Vol 44 (6) ◽  
pp. 845-848 ◽  
Author(s):  
K. W. Joy
Keyword(s):  
Amino Acid ◽  
Nitrogen Metabolism ◽  
Lemna Minor ◽  
Nitrogen Sources ◽  
Acid Inhibition

Genetic regulation of nitrogen metabolism in the fungi

1997 ◽  
Vol 61 (1) ◽  
pp. 17-32
Author(s):  
G A Marzluf
Keyword(s):  
Nitrogen Metabolism ◽  
Protein Interactions ◽  
Fungal Pathogens ◽  
Metabolic Regulation ◽  
Specific Binding ◽  
Genetic Regulation ◽  
Nitrogen Sources ◽  
Specific Protein ◽  
Genes Encoding ◽  
Gata Family

In the fungi, nitrogen metabolism is controlled by a complex genetic regulatory circuit which ensures the preferential use of primary nitrogen sources and also confers the ability to use many different secondary nitrogen sources when appropriate. Most structural genes encoding nitrogen catabolic enzymes are subject to nitrogen catabolite repression, mediated by positive-acting transcription factors of the GATA family of proteins. However, certain GATA family members, such as the yeast DAL80 factor, act negatively to repress gene expression. Selective expression of the genes which encode enzymes for the metabolism of secondary nitrogen sources is often achieved by induction, mediated by pathway-specific factors, many of which have a GAL4-like C6/Zn2 DNA binding domain. Regulation within the nitrogen circuit also involves specific protein-protein interactions, as exemplified by the specific binding of the negative-acting NMR protein with the positive-acting NIT2 protein of Neurospora crassa. Nitrogen metabolic regulation appears to play a significant role in the pathogenicity of certain animal and plant fungal pathogens.

Ammonia regulation of amino acid permeases in Saccharomyces cerevisiae

1983 ◽  
Vol 3 (4) ◽  
pp. 672-683
Author(s):  
W E Courchesne ◽  
B Magasanik
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Cytoplasmic Membrane ◽  
Nitrogen Sources ◽  
Amino Acid Permease ◽  
Inducer Exclusion ◽  
Amino Acid Permeases ◽  
General Amino Acid Permease ◽  
State Growth ◽  
And Control

The activities of the proline-specific permease (PUT4) and the general amino acid permease (GAP1) of Saccharomyces cerevisiae vary 70- to 140-fold in response to the nitrogen source of the growth medium. The PUT4 and GAP1 permease activities are regulated by control of synthesis and control of activity. These permeases are irreversibly inactivated by addition of ammonia or glutamine, lowering the activity to that found during steady-state growth on these nitrogen sources. Mutants altered in the regulation of the PUT4 permease (Per-) have been isolated. The mutations in these strains are pleiotropic and affect many other permeases, but have no direct effect on various cytoplasmic enzymes involved in nitrogen assimilation. In strains having one class of mutations (per1), ammonia inactivation of the PUT4 and GAP1 permeases did not occur, whereas glutamate and glutamine inactivation did. Thus, there appear to be two independent inactivation systems, one responding to ammonia and one responding to glutamate (or a metabolite of glutamate). The mutations were found to be nuclear and recessive. The inactivation systems are constitutive and do not require transport of the effector molecules per se, apparently operating on the inside of the cytoplasmic membrane. The ammonia inactivation was found not to require a functional glutamate dehydrogenase (NADP). These mutants were used to show that ammonia exerts control of arginase synthesis largely by inducer exclusion. This may be the primary mode of nitrogen regulation for most nitrogen-regulated enzymes of S. cerevisiae.

THE INFLUENCE OF THE PINEAL GLAND ON NITROGEN METABOLISM

1969 ◽  
Vol 45 (2) ◽  
pp. 175-181 ◽  
Author(s):  
IOANA MILCU ◽  
LYDIA NANU-IONESCU ◽  
RODICA MARCEAN ◽  
VIOLETA IONESCU
Keyword(s):  
Growth Hormone ◽  
Amino Acid ◽  
Pineal Gland ◽  
Nitrogen Metabolism ◽  
Intravenous Administration ◽  
Protein Metabolism ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Test Substance ◽  
Anabolic Action

SUMMARY The influence of the pineal gland on protein metabolism was investigated by using a test previously devised for studying the anabolic action of growth hormone. This test consists in measuring the accumulation of urea in blood after the intravenous administration of an amino acid mixture to nephrectomized rats injected with the test substance. Like growth hormone, pineal extract significantly reduced the quantity of urea formed, suggesting an anabolic action. In contrast, in pinealectomized animals, the quantity of urea formed significantly increased when compared with controls.

Amino acid uptake systems in Bacteroides ruminicola

1979 ◽  
Vol 25 (10) ◽  
pp. 1161-1168 ◽  
Author(s):  
Roselynn M. W. Stevenson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Nitrogen Sources ◽  
Amino Acid Uptake ◽  
Defined Medium ◽  
High Rate ◽  
Transport Systems ◽  
Acid Uptake ◽  
Chemical Structures ◽  
Kinetic Inhibition

Uptake of amino acids by Bacteroides ruminicola was observed in cells grown in a complete defined medium, containing ammonia as the nitrogen source. A high rate of uptake occurred only in fresh medium, as an inhibitory substance, possibly acetate, apparently accumulated during growth. All amino acids except proline were taken up and incorporated into cold trichloroacetic acid precipitable material. Different patterns of incorporation and different responses to 2,4-dinitrophenol and potassium ferricyanide indicated multiple uptake systems were involved. Kinetic inhibition patterns suggested six distinct systems were present for amino acid uptake, with specificities related to the chemical structures of the amino acids. Thus, the failure of free amino acids to act as sole nitrogen sources for growth of B. ruminicola is not due to the absence of transport systems for these compounds.

Complete genome sequence ofParacoccus denitrificansATCC 19367 and its denitrification characteristics

2019 ◽  
Vol 65 (7) ◽  
pp. 486-495 ◽  
Author(s):  
Yuan-yuan Si ◽  
Kai-hang Xu ◽  
Xiang-yong Yu ◽  
Mei-fang Wang ◽  
Xing-han Chen
Keyword(s):  
Nitrogen Metabolism ◽  
Genome Sequence ◽  
Complete Genome ◽  
Paracoccus Denitrificans ◽  
Nitrogen Sources ◽  
Trna Genes ◽  
Protein Coding ◽  
Aerobic Conditions ◽  
Practical Applications ◽  
Protein Coding Genes

Studies show that Paracoccus denitrificans can denitrify nitrogen sources under aerobic conditions. However, the lack of data on its genome sequence has restricted molecular studies and practical applications. In this study, the complete genome of P. denitrificans ATCC 19367 was sequenced and its nitrogen metabolism properties were characterized. The size of the whole genome is 5 242 327 bp, with two chromosomes and one plasmid. The average G + C content is 66.8%, and it contains 5308 protein-coding genes, 54 tRNA genes, and nine rRNA operons. Among the protein-coding genes, 71.35% could be assigned to the Gene Ontology (GO) pathway, 86.66% to the Clusters of Orthologous Groups (COG) pathway, and 50.57% to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Comparative genome analysis between P. denitrificans ATCC 19367 and P. denitrificans PD1222 revealed that there are 428 genes specific to ATCC 19367 and 4738 core genes. Furthermore, the expression of genes related to denitrification, biofilm formation, and nitrogen metabolism (nar, nir, and nor) by P. denitrificans ATCC 19367 under aerobic conditions was affected by incubation time and shaking speed. This study elucidates the genomic background of P. denitrificans ATCC 19367 and suggests the possibility of controlling nitrogen pollution in the environment by using this bacterium.

scholarly journals Nitrogen Supply and Leaf Age Affect the Expression of TaGS1 or TaGS2 Driven by a Constitutive Promoter in Transgenic Tobacco

Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 406 ◽  
Author(s):  
Yihao Wei ◽  
Aibo Shi ◽  
Xiting Jia ◽  
Zhiyong Zhang ◽  
Xinming Ma ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nitrogen Metabolism ◽  
Soluble Protein ◽  
Leaf Age ◽  
Sufficient Conditions ◽  
Transcript Level ◽  
Nitrogen Supply ◽  
High Accumulation ◽  
Transcript Levels ◽  
Chlorophyll Contents

Glutamine synthetase (GS) plays a key role in nitrogen metabolism. Here, two types of tobacco transformants, overexpressing Triticum aestivum GS1 (TaGS1) or GS2 (TaGS2), were analysed. Four independent transformed lines, GS1-TR1, GS1-TR2, GS2-TR1 and GS2-TR2, were used for the nitrogen treatment. Under nitrogen-sufficient conditions, the leaves of GS2-TR showed high accumulation of the TaGS2 transcript, while those of GS1-TR showed a low TaGS1 transcript levels. However, compared with nitrogen-sufficient conditions, the TaGS1 transcript level increased in the leaves under nitrogen starvation, but the TaGS2 transcript level decreased. In addition, the TaGS1 and TaGS2 transcript levels were highest in the middle leaves under nitrogen-sufficient and starvation conditions. These results show that nitrogen supply and leaf age regulate TaGS expression, even when they are driven by a super-promoter. Additionally, in regard to nitrogen metabolism level, the lower leaves of the GS1-TR exhibited lower NH4+ and higher amino acid contents, while the upper leaves exhibited higher amino acid, soluble protein and chlorophyll contents. The leaves of the GS2-TR exhibited lower NH4+ but higher amino acid, soluble protein and chlorophyll contents. Given the role that GS isoforms play in nitrogen metabolism, these data suggest that TaGS1 overexpression may improve nitrogen transport, and that TaGS2 overexpression may improve nitrogen assimilation under nitrogen stress.

Plant NAD-Dependent Glutamate Dehydrogenase. Purification, Molecular Properties and Metal Ion Activation of the Enzymes from Lemna minor and Pisum sativum

1980 ◽  
Vol 35 (3-4) ◽  
pp. 213-221 ◽  
Author(s):  
Heinz-Walter Scheid ◽  
Adelheid Ehmke ◽  
Thomas Hartmann
Keyword(s):  
Amino Acid ◽  
Pisum Sativum ◽  
Glutamate Dehydrogenase ◽  
Gel Electrophoresis ◽  
Metal Ion ◽  
Lemna Minor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Sedimentation Equilibrium ◽  
Electron Microscopic

Abstract Glutamate dehydrogenase (ʟ-glutamate: NAD+ oxidoreductase (deaminating) EC 1.4.1.2) has been purified to homogeneity from Lemna minor and seeds of Pisum sativum. As established by polyacrylamide gel electrophoresis the Pisum-enzyme constitutes a multiple pattern of seven char­ge isoenzymes whereas the Lemna enzyme shows one single protein band. Molecular weights of 230 000 were calculated for both enzymes by sedimentation equilibrium measurements (Pisum-enzyme) and comparative gel filtration (Lemna-enzyme). Sodium dodecyl sulfate gel electrophoresis and electron microscopic observations revealed that both enzymes are composed of four identical subunits (molecular weight 58 500) arranged in a tetraedric structure. The amino acid compositions of both enzymes are similar to those of various hexameric glutamate dehydrogenases. The N-terminal amino acid of the Pisum-enzyme is alanine. Both enzymes require Ca2+ for maximal catalytic activity. For the Lemna-enzyme the K0.5 values for Ca2+ are 22 µᴍ (NADH-dependent reaction) and 4 µᴍ (NAD+ -dependent reaction), respectively. Ca2+ which to some extent can be replaced by Zn2+ does not affect the enzyme aggregation but seems to govern a reversible equilibrium between catalytically active and inactive enzyme forms.

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