Phosphoenolpyruvate Carboxylase Level in Soybean Seed Highly Correlates to Its Contents of Protein and Lipid

Sugimoto, Toshio; Tanaka, Kiyoshi; Monma, Michiko; Kawamura, Yukio; Saio, Kyoko

doi:10.1080/00021369.1989.10869369

Cited by 17 publications

(16 citation statements)

References 2 publications

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“…Directing more carbon from sugars into protein synthesis by increasing anaplerotic flux via PEP carboxylase has also been proposed as a strategy to increase protein content in seeds (41)(42)(43). However, as shown in Fig.…”

Section: Mitochondrial Metabolism Does Not Provide Precursors For Plamentioning

confidence: 94%

Mitochondrial Metabolism in Developing Embryos of Brassica napus

Schwender

Shachar‐Hill

Ohlrogge

2006

Journal of Biological Chemistry

216

283

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The metabolism of developing plant seeds is directed toward transforming primary assimilatory products (sugars and amino acids) into seed storage compounds. To understand the role of mitochondria in this metabolism, metabolic fluxes were determined in developing embryos of Brassica napus. After labeling with [1,2-13 C 2 ]glucose ؉ [U- 13 N]glutamine, the resulting labeling patterns in protein amino acids and in fatty acids were analyzed by gas chromatography-mass spectrometry. Fluxes through mitochondrial metabolism were quantified using a steady state flux model. Labeling information from experiments using different labeled substrates was essential for model validation and reliable flux estimation. The resulting flux map shows that mitochondrial metabolism in these developing seeds is very different from that in either heterotrophic or autotrophic plant tissues or in most other organisms: (i) flux around the tricarboxylic acid cycle is absent and the small fluxes through oxidative reactions in the mitochondrion can generate (via oxidative phosphorylation) at most 22% of the ATP needed for biosynthesis; (ii) isocitrate dehydrogenase is reversible in vivo; (iii) about 40% of mitochondrial pyruvate is produced by malic enzyme rather than being imported from the cytosol; (iv) mitochondrial flux is largely devoted to providing precursors for cytosolic fatty acid elongation; and (v) the uptake of amino acids rather than anaplerosis via PEP carboxylase determines carbon flow into storage proteins.Directly or indirectly plant seeds provide most of the food consumed by humans. Although the metabolism of developing seeds has been extensively studied, quantitative understanding of fluxes through central metabolism is still quite limited. Brassica napus (canola, oilseed rape) is a major oil crop and is amenable to detailed quantitative flux analysis under conditions that closely mimic in planta seed development (1). The main storage compounds in seeds of B. napus are oil (triacylglycerols) and proteins, which are synthesized by the developing embryo from sugars and amino acids taken up from the surrounding endosperm liquid.Developing seeds of B. napus have also been the subject of numerous biochemical studies and are a model for oil accumulating seeds (2-13). In previous studies we have used intact developing embryos to make a quantitative analysis of steadystate metabolic fluxes during the conversion of carbohydrates to fatty acids in vivo (1, 14 -17). These studies introduced a labeling approach using multiple carbon sources (1), quantified the contribution of the oxidative pentose phosphate pathway to biosynthetic NADPH demands (14), and revealed that ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) 2 operates in a novel context of carbohydrate conversion to fatty acids, bypassing glycolytic reactions and increasing the efficiency of seed carbon metabolism (16). However, a detailed description of fluxes through mitochondrial metabolism in B. napus or other developing seeds is lacking.Several functions of mitoc...

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Section: Mitochondrial Metabolism Does Not Provide Precursors For Plamentioning

confidence: 94%

Mitochondrial Metabolism in Developing Embryos of Brassica napus

Schwender

Shachar‐Hill

Ohlrogge

2006

Journal of Biological Chemistry

216

283

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“…Its enzyme activity was positively correlated with protein content and inversely with lipid content (Sugimoto et al, 1989). Because proteins >100 kD are difficult to detect by 2-D technology, we detected the PEPC by Western blot analysis (Fig.…”

Section: Western Blot Analysis Of Phosphoenolpyruvate Carboxylase Andmentioning

confidence: 98%

Integrated and comparative proteomics of high-oil and high-protein soybean seeds

Liu

Tian

et al. 2015

Food Chemistry

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“…The nucleotide sequence of gmppcl6 with the predicted ~anslafion product indicted below the coding sequence. protein storage levels in seeds [ 15]. To investigate the roles played by PEPC in C3 plants, we cloned a PEPC c D N A from soybean.…”

Section: T a A T L E H G M H P P 7 0 2 2221 C A A T T T C T C C T A Amentioning

confidence: 99%

cDNA sequence and expression of a phosphoenolpyruvate carboxylase gene from soybean

et al. 1992

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A full-length cDNA encoding a subunit of phosphoenolpyruvate carboxylase (PEPC) was isolated from a developing seed expression library of the C3 plant Glycine max. The corresponding mRNA is present at similar levels in leaf, stem, root and developing seed. Two potential start codons exist, and the activity of protein initiated from the first such codon could be subject to regulation by protein kinase. Sequence comparison shows a similar upstream start codon in the case of the Ppc2 gene from Mesembryanthemum crystallinum, previously assumed to lack the sequences necessary for phosphorylation. The soybean encoded protein tends to resemble other 'C3-type' PEPC proteins more closely than those implicated in C4 or crassulacean acid metabolism.

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Phosphoenolpyruvate Carboxylase Level in Soybean Seed Highly Correlates to Its Contents of Protein and Lipid

Cited by 17 publications

References 2 publications

Mitochondrial Metabolism in Developing Embryos of Brassica napus

Mitochondrial Metabolism in Developing Embryos of Brassica napus

Integrated and comparative proteomics of high-oil and high-protein soybean seeds

cDNA sequence and expression of a phosphoenolpyruvate carboxylase gene from soybean

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