Genetic control of lysine metabolism in maize endosperm mutants

2004 ◽  
Vol 31 (4) ◽  
pp. 339 ◽  
Author(s):  
Ricardo A. Azevedo ◽  
Catherine Damerval ◽  
Peter J. Lea ◽  
Jacques Landry ◽  
Cláudia M. Bellato ◽  
...  
Keyword(s):  
Amino Acids ◽  
Qualitative Study ◽  
Aspartate Kinase ◽  
Maize Endosperm ◽  
Homoserine Dehydrogenase ◽  
Saccharopine Dehydrogenase ◽  
Endosperm Mutants ◽  
Mutant Lines ◽  
Mutant Genes ◽  
Lysine Metabolism

The capacity of three maize endosperm opaque mutants (o10, o11 and o13) to accumulate soluble lysine in the seed in relation to their wildtype counterpart, W22+, was investigated. The W22o13 and W22o11 mutants exhibited 278% and 186% increases in soluble lysine, respectively, while for W22o10, a 36% decrease was observed, compared with the wildtype. A quantitative and qualitative study of the N constituents of the endosperm has been conducted and data obtained for the total protein, non-protein N, soluble amino acids, albumins / globulins, zeins and glutelins present in the seed of the mutants. Following 2D–PAGE, a total of 38 different forms of zein polypeptides were detected and considerable differences were noted between the three mutant lines. The metabolism of lysine was also studied by analysis of the enzymes aspartate kinase, homoserine dehydrogenase, lysine 2-oxoglutarate reductase and saccharopine dehydrogenase, which exhibited major changes in activity, depending on the genotype, suggesting that the mutant genes may have distinct regulatory activities.

scholarly journals Isolation of enzymes involved in threonine biosynthesis from sorghum seeds

2004 ◽  
Vol 16 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Renato Rodrigues Ferreira ◽  
Ariane Vendemiatti ◽  
Lyndel Wayne Meinhardt ◽  
Peter John Lea ◽  
Ricardo Antunes Azevedo
Keyword(s):  
Amino Acids ◽  
Essential Amino Acids ◽  
Aspartate Kinase ◽  
Homoserine Dehydrogenase ◽  
Higher Plant ◽  
Level Of Activity ◽  
Immature Seeds ◽  
Aspartate Pathway ◽  
Threonine Biosynthesis

Cereal seeds are poor in essential amino acids, particularly lysine, tryptophan and threonine. The amino acids lysine and threonine are synthesized in the aspartate pathway. Although most of the enzymes of the aspartate pathway have been isolated and characterized in higher plant species, the metabolism of lysine and threonine is totally unknown in sorghum. We have isolated two enzymes, aspartate kinase (AK) and homoserine dehydrogenase (HSDH) from sorghum. Optimum assay conditions were established for the determination of AK and HSDH activities. The highest level of activity was observed in immature seeds. AK was shown to be inhibited by threonine and lysine indicating the existence of at least two isoenzymes, one sensitive to threonine inhibition and the other sensitive to lysine inhibition with the latter being predominant in sorghum seeds. HSDH was shown to be inhibited by threonine indicating the existence of a threonine-sensitive HSDH, however, most of the activity was not inhibited by threonine, suggesting the existence of a second predominant isoenzyme of HSDH resistant to threonine inhibition.

scholarly journals Distribution of soluble amino acids in maize endosperm mutants

2003 ◽  
Vol 60 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Alejandro Alberto Toro ◽  
Leonardo Oliveira Medici ◽  
Ladaslav Sodek ◽  
Peter John Lea ◽  
Ricardo Antunes Azevedo
Keyword(s):  
Amino Acids ◽  
Storage Proteins ◽  
Soluble Form ◽  
Average Content ◽  
Wild Type ◽  
Maize Endosperm ◽  
Legume Seeds ◽  
Wild Type Counterpart ◽  
Endosperm Mutants ◽  
Mature Endosperm

For human nutrition the main source of vegetable proteins are cereal and legume seeds. The content of total soluble amino acids in mature endosperm of wild-type, opaque and floury maize (Zea mays L.) mutants were determined by HPLC. The total absolute concentration of soluble amino acids among the mutants varied depending on the mutant. The o11 and o13 mutants exhibited the highest average content, whereas o10, fl3 and fl1 exhibited the lowest average content. In general, the mutants exhibited similar concentrations of total soluble amino acids when compared to the wild-type lines, with the clear exception of mutants o11 and fl1, with the o11 mutant exhibiting a higher concentration of total soluble amino acids when compared to its wild-type counterpart W22 and the fl1 mutant a lower concentration when compared to its wild-type counterpart Oh43. For methionine, the mutants o2 and o11 and wild-type Oh43 exhibited the highest concentrations of this amino acid. Significant differences were not observed between mutants for other amino acids such as lysine and threonine. The high lysine concentrations obtained originally for these mutants may be due to the amino acids incorporated into storage proteins, but not those present in the soluble form.

Influence of Maize Endosperm Mutants on Ground Kernel In Vitro Dry Matter Disappearance 1

Crop Science ◽  
1974 ◽  
Vol 14 (5) ◽  
pp. 676-678
Author(s):  
D. L. Garwood ◽  
J. S. Shenk ◽  
R. F. Barnes
Keyword(s):  
Dry Matter ◽  
Maize Endosperm ◽  
Endosperm Mutants ◽  
Ground Kernel

A novel bifunctional aspartate kinase-homoserine dehydrogenase from the hyperthermophilic bacterium, Thermotoga maritima

2018 ◽  
Vol 82 (12) ◽  
pp. 2084-2093
Author(s):  
Tatsuya Ohshida ◽  
Kohei Koba ◽  
Junji Hayashi ◽  
Kazunari Yoneda ◽  
Taketo Ohmori ◽  
...  
Keyword(s):  
Thermotoga Maritima ◽  
Aspartate Kinase ◽  
Homoserine Dehydrogenase ◽  
Hyperthermophilic Bacterium

Cellular Amino Acid Concentrations and Regulation of Aspartate Kinase in the Thermophilic Phototrophic Prokaryote Chloroflexus aurantiacus

1990 ◽  
Vol 45 (1-2) ◽  
pp. 74-78 ◽  
Author(s):  
Jobst-Heinrich Klemme ◽  
Gisela Laakmann-Ditges ◽  
Jutta Mertschuweit
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Gel Filtration ◽  
Break Point ◽  
Test System ◽  
Chloroflexus Aurantiacus ◽  
Aspartate Kinase ◽  
Homoserine Dehydrogenase ◽  
Molecular Weights ◽  
Amino Acid Concentrations

Aspartate kinase (AK , EC 2.7.2.4) from the thermophilic, phototrophic prokaryote, Chloroflexus aurantiacus, was partially purified and separated from homoserine dehydrogenase (HSDH, EC 1.1.1.3). The molecular weights as determined by gel filtration were 130,000 and 46,000, respectively. HSDH had a moderately high thermal stability (50% inactivation at 84 °C) and displayed its activity optimum at 72 °C. By contrast, AK had its activity optimum at 52 °C (with a break-point in the Arrhenius plot at 42 °C) and was much less thermostable (50% inactivation at 67 °C). The Km-values for aspartate and ATP (determined in a pyruvate kinase-coupled test system) were 10.5 and 0.63 mM , respectively. The enzyme was strongly inhibited by L-threonine (Ki = 10 μm) and activated by alanine, isoleucine, valine and methionine. L-Threonine acted as a mixed-type inhibitor in respect to aspartate, and non-competitively in respect to ATP. Contrary to AKs from Rhodospirillaceae, the enzyme from Chloroflexus aurantiacus was not subject to a concerted feedback inhibition by two amino acids of the aspartate family. The regulatory properties of the aspartate kinase are discussed in relation to the cellular amino acid concentrations.

Expression of A/B zeins in single and double maize endosperm mutants

1992 ◽  
Vol 85 (4) ◽  
pp. 407-414 ◽  
Author(s):  
J. W. Paulis ◽  
J. A. Bietz ◽  
T. P. Bogyo ◽  
T. C. Nelsen ◽  
L. L. Darrah ◽  
...  
Keyword(s):  
Maize Endosperm ◽  
Endosperm Mutants

Variations in β-aspartate kinase activity during the development of maize endosperm

FEBS Letters ◽  
1979 ◽  
Vol 99 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Randolph R. Henke ◽  
Rosemarie Wahnbaeck-Spencer
Keyword(s):  
Kinase Activity ◽  
Aspartate Kinase ◽  
Maize Endosperm
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