Amino Acid Transport in Protoplasts Isolated from Soybean Leaves

Vernooy, Charles D.; Lin, Willy

doi:10.1104/pp.81.1.8

Cited by 9 publications

(5 citation statements)

References 10 publications

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“…The phenylpropanoid pathway leads to lignin biosynthesis suggesting, at least in part, the beginning of senescence. The low levels of glutamic acid and alanine in the vacuolar compartment (Table 2) and the high levels of glycine in chloroplast compartment (Table 2) may suggest low storage of nitrogen in leaves, and the ready export of amino acid metabolites, as it has been earlier reported that amino acids accumulation is greater in the sink than in the source in soybean leaves (VerNooy and Lin 1986).…”

Section: Metabolite Profiling 301mentioning

confidence: 87%

Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis

2007

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In the present study, non-aqueous fractionation (NAQF) and GC-MS were used to obtain a spatially resolved view of metabolism in mature leaves of soybean (Glycine max Merr.). NAQF of lyophilized soybean leaves was performed using CCl 4 -n-heptane and ultracentrifugation that yielded a gradient comprised of six fractions. Chlorophyll content, and marker enzyme activities, phosphoenolpyruvate carboxylase (PEPC) and a-mannosidase, were utilized as stroma, cytosol and vacuole markers, respectively. GC-MS analyses of each fraction resulted in the identification of around 100 different metabolites. The distribution of these identified compounds showed a decreasing order from the vacuole to cytosol to chloroplast stroma. In other words, a greater number of identified compounds were found in the vacuole when compared to the cytosol or stroma.Levels of sugars, organic acids and fatty acids showed greater relative abundances in the vacuole with 50, 55, and 50% of the respective pools. A greater relative abundance of amino acids was observed in the cytosol where 45% of the total of amino acids content was recorded. The relatively large pool of sugars and phenolic acids in the vacuole compartment implies high levels of starch metabolism and phenylpropanoid biosynthesis. The low amino acids pool, on the other hand, suggests low nitrogen accumulation in the leaves of soybean. Hierarchical cluster analysis on the most abundant metabolites revealed three clusters containing 10, 20, and 2 of the 32 selected metabolites. The data were discussed in term of NAQF and GC-MS analysis of soybean mature leaves, and also in term of distribution and compartmentation of metabolites at subcellular levels.

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Section: Metabolite Profiling 301mentioning

confidence: 87%

Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis

2007

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“…Although these systems have provided important insight into the nature of amino acid transport, this experimental approach is limited by a number of problems which can compromise investigations of membrane bound transport systems. For example, rapid metabolism of the transported amino acid can lead to an overestimate of transport stoichiometries and metabolically linked feedback control systems may significantly influence transport activity (3,20,24). Furthermore, differential rates of accumulation by the various cell types present in an intact tissue and the existence of ill-defined diffusion barriers may further complicate interpretation.…”

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confidence: 99%

“…Amino acid transport in plants is frequently associated with accumulation against a significant free energy gradient across the plasma membrane. Several lines of evidence have linked this active transport process to the proton electrochemical difference generated by the plasma membrane proton-pumping ATPase (10, 13,15,20,[23][24][25] and recently, Bush and Langston-Unkefer (6) provided the first in vitro evidence demonstrating proton-amino acid symport activity in isolated plasma membrane vesicles.…”

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confidence: 99%

ΔpH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet Leaves

Bush²

1990

Plant Physiol.

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Amino acid transport into plasma membrane vesicles isolated from mature sugar beet (Beta vulgaris L. cv Great Westem) leaves was investigated. The transport of alanine, leucine, glutamine, glutamate, isoleucine, and arginine was driven by a trans-membrane proton concentration difference. ApH-Dependent alanine, leucine, glutamine, and glutamate transport exhibited simple Michaelis-Menten kinetics, and double-reciprocal plots of the data were linear with apparent Km values of 272, 346, 258, and 1981 micromolar, respectively. These results are consistent with carrier mediated transport. ApH-Dependent isoleucine and arginine transport exhibited biphasic kinetics, suggesting these amino acids may be transported by at least two transport systems. Symport mediated alanine transport was electrogenic as demonstrated by the effect of membrane potential (A*) on ApHdependent flux. In the absence of significant charge compensation, a low rate of alanine transport was observed. When A' was held at 0 millivolt with symmetric potassium concentrations and valinomycin, the rate of flux was stimulated fourfold. In the presence of a negative A+, alanine transport increased sixfold. These results are consistent with an electrogenic transport process which results in a net flux of positive charge into the vesicles.The effect of changing AI on the kinetics of alanine transport altered Vmax with no apparent change in Km. Amino acid transport was inhibited by the protein modifier diethyl pyrocarbonate, but was insensitive to N-ethylmaleimide, 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid, p-chloromercuribenzenesulfonic acid, phenylglyoxal, and N,N'-dicyclohexylcarbodiimide. Four amino acid symport systems, two neutral, one acidic, and one basic, were resolved based on inter-amino acid competition experiments. One neutral system appears to be active for all neutral amino acids while the second exhibited a low affinity for isoleucine, threonine, valine, and proline. Although each symport was relatively specific for a given group of amino acids, each system exhibited some crossover specificity for amino acids in other groups.

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“…lism in a variety of plant systems (3,15 (13). We determined that chloramphenicol at 50 gg ml-' in the uptake and efflux media had no noticeable effect on uptake or passive efflux of aAIB, indicating that microbial contamination was not a problem in these relatively long-term experiments.…”

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confidence: 99%

Transport and Compartmentation of 1-Aminocyclopropane-1-Carboxylic Acid and Its Structural Analog, α-Aminoisobutyric Acid, in Tomato Pericarp Slices

Saftner¹,

Baker²

1987

Plant Physiol.

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ABSTRACFThe uptakes of 1-aminocyclopropane-I-carboxylic acid (ACC), the immediate precursor to ethylene, and its strutural analog, a-aminoisobutyric acid (aAIB) by tomato pencarp slices were investigated. Both uptakes show a biphasic (saturable-linear) dependence on external concentration of the transported amino acid. At low concentrations, ACC uptake is competitively inhibited by aAIB and vice versa. Both uptakes also are inhibited by other neutral amino acids but not by acidic or basic amino acids. ACC and aAIB uptakes are metabolically dependent and are increased with time of tissue incubatio aAIB efflux patterns from pericarp slices indicated three distinct aAIB compartments having efflux kinetics consistent with those for cell wall, cytoplasm, and vacnole. The bulk of the aAIB taken up by pericarp tissue is sequestered into the vacoole. The ability of pericarp tissue to accumulate rAAB in the vacoole declines with fruit development.

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Amino Acid Transport in Protoplasts Isolated from Soybean Leaves

Cited by 9 publications

References 10 publications

Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis

Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis

ΔpH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet Leaves

Transport and Compartmentation of 1-Aminocyclopropane-1-Carboxylic Acid and Its Structural Analog, α-Aminoisobutyric Acid, in Tomato Pericarp Slices

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