Properties of Citrate-stimulated Starch Synthesis Catalyzed by Starch Synthase I of Developing Maize Kernels

Boyer, Charles D.; Preiss, Jack

doi:10.1104/pp.64.6.1039

Cited by 59 publications

(27 citation statements)

References 11 publications

(17 reference statements)

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“…Additional evidence exists for functional interactions between starch biosynthetic enzymes. In maize kernel extracts, the activity of SSI was greatly stimulated by the addition of purified SBEI or SBEII (Boyer and Preiss, 1979). Recently, Seo et al (2002) showed that functional interactions exist between heterologously expressed SBEs from maize and yeast glycogen synthases working in a cyclically interdependent fashion, which is consistent with the idea that starch metabolizing enzymes may function in protein complexes.…”

Section: ª 2004 American Society Of Plant Biologistssupporting

confidence: 66%

Protein Phosphorylation in Amyloplasts Regulates Starch Branching Enzyme Activity and Protein–Protein Interactions

et al. 2004

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Protein phosphorylation in amyloplasts and chloroplasts of Triticum aestivum (wheat) was investigated after the incubation of intact plastids with g-32 P-ATP. Among the soluble phosphoproteins detected in plastids, three forms of starch branching enzyme (SBE) were phosphorylated in amyloplasts (SBEI, SBEIIa, and SBEIIb), and both forms of SBE in chloroplasts (SBEI and SBEIIa) were shown to be phosphorylated after sequencing of the immunoprecipitated 32 P-labeled phosphoproteins using quadrupole-orthogonal acceleration time of flight mass spectrometry. Phosphoamino acid analysis of the phosphorylated SBE forms indicated that the proteins are all phosphorylated on Ser residues. Analysis of starch granuleassociated phosphoproteins after incubation of intact amyloplasts with g-32 P-ATP indicated that the granule-associated forms of SBEII and two granule-associated forms of starch synthase (SS) are phosphorylated, including SSIIa. Measurement of SBE activity in amyloplasts and chloroplasts showed that phosphorylation activated SBEIIa (and SBEIIb in amyloplasts), whereas dephosphorylation using alkaline phosphatase reduced the catalytic activity of both enzymes. Phosphorylation and dephosphorylation had no effect on the measurable activity of SBEI in amyloplasts and chloroplasts, and the activities of both granule-bound forms of SBEII in amyloplasts were unaffected by dephosphorylation. Immunoprecipitation experiments using peptide-specific anti-SBE antibodies showed that SBEIIb and starch phosphorylase each coimmunoprecipitated with SBEI in a phosphorylation-dependent manner, suggesting that these enzymes may form protein complexes within the amyloplast in vivo. Conversely, dephosphorylation of immunoprecipitated protein complex led to its disassembly. This article reports direct evidence that enzymes of starch metabolism (amylopectin synthesis) are regulated by protein phosphorylation and indicate a wider role for protein phosphorylation and protein-protein interactions in the control of starch anabolism and catabolism.

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Section: ª 2004 American Society Of Plant Biologistssupporting

confidence: 66%

Protein Phosphorylation in Amyloplasts Regulates Starch Branching Enzyme Activity and Protein–Protein Interactions

et al. 2004

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“…In contrast, unprimed soluble starch synthase activity is totally dependent on high amounts of sodium citrate or sodium malate in in vitro experiments (3,12,20,23,25). In case of potato, at least 0.4 M sodium citrate was necessary to stimulate the unprimed soluble starch synthase activity in vitro (Fig.…”

Section: Unprimed Soluble Starch Synthase Activity Depends On High Ammentioning

confidence: 99%

“…Sodium dithionite (0.2% w/v) and DTT (1 mM), often used to stabilize the soluble starch synthases (3,12,25), had no effect on ADP-Glc incorporation into tissue slices (Fig. 1, lanes E and F).…”

Section: Incorporation Of Adp-gic Into Potato Tuber Slicesmentioning

confidence: 99%

“…Elongation of both starch components has been studied in vitro by using (partly) purified enzymes (3,9,10,20,24,25). However, since starch synthesis and assembly into starch granules are complex processes, it is difficult to mimic adequately in vivo conditions in vitro.…”

mentioning

confidence: 99%

“…It elongates both amylopectin and glycogen, its reactivity being higher for amylopectin. Since enzymatic activity is also measurable without exogenously added primer molecules in the presence of at least 0.25 M of sodium citrate or sodium malate (3,12,25), the enzyme is referred to as the 'unprimed soluble starch synthase.' The incorporation of ADP-Glc into amylopectin is stimulated fivefold by 0.5 M sodium citrate (20).…”

mentioning

confidence: 99%

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Selective Measurement of Starch Synthesizing Enzymes in Permeabilized Potato Tuber Slices

Ponstein

Vos-Scheperkeuter²,

Jacobsen³

et al. 1990

Plant Physiol.

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Osmotically permeabilized potato (Solanum tuberosum L.) tuber slices were used to study the biosynthesis of starch under semi in vivo conditions. Criteria to distinguish the various enzymes involved in starch biosynthesis were developed based on the characteristics of the enzymes in in vitro experiments. Branching enzyme activity was inhibited at pH 8.5 or higher, while the starch synthases functioned optimally between pH 8.8 and 9.1. Unprimed soluble starch synthase activity was only apparent in the presence of sodium citrate (0.4 molar or higher). Granulebound and primed soluble starch synthase were active in the absence of sodium citrate. Primed soluble starch synthase activity was susceptible to inhibition by 10 millimolar zinc sulfate, while granule-bound starch synthase activity was not. The incorporation of the Glc moiety of ADP-Glc into starch in tissue slices by the various starch synthases was consistent with in vitro data with respect to the affinity of the enzymes for substrate, the pH profile, the stimulation by citrate, and the inhibition by zinc sulfate. These data were used to determine the activity of each of the starch synthases in tissue slices: granule-bound and soluble starch synthase transferred 37 and 55 picomoles ADP-Glc per hour per milligram fresh weight into starch of permeabilized tissue slices at 300C and pH 9.1. In the presence of 0.5 molar sodium citrate, at least 40 picomoles ADP-Glc per hour per milligram fresh weight as transferred into starch by unprimed soluble starch synthase activity.

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Genetic Engineering, Plants

Edwards

Kishore

Stark

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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J ANICE W. E DWARDS , G ANESH M. K ISHORE and D AVID M. S TARK (Monsanto Company) Several discoveries in the 1980s and 1990s permitted the transition of plant molecular biology from a fledgling science to commercial reality. These discoveries ranged from the identification of biologically important genes to the development of methods to introduce new genes into plants transformation and regulate gene expression. Nearly five dozen plant species have been transformed and the list of plant species subject to transformation include principal field crops such as corn, cotton, rape, rice, soybean, and wheat. In addition, several horticultural species such as tomato, potato, etc, have been subject to transformation. More than 500 field tests have been conducted and transgenic plants such as transgenic tomato, soybean, corn, rape, etc, are in the advanced stages of commercial development and regulatory process. Four methods have been extensively investigated for the introduction of transferred deoxyribonucleic acid (T‐DNA) into plants. Most common direct uptake of DNA by protoplasts, particle acceleration techniques such as electrostatic discharge or biolistics gun technology, and DNA uptake into partially digested immature embryos. Expression of genes that have been introduced into plants is regulated by promoters, although the extent of regulation of gene activity by the promoter is influenced at least to some extent by the insertion site of the gene within the chromosome. The choice of promoters is dictated by the tissue and developmental specificity required for gene expression. Two specific applications of plant biotechnology include engineering tolerance to the widely used herbicide glyphosate, C 3 H 8 NO 5 P, and increasing starch biosynthesis in plants. Both tomato fruit ripening and fruit firmness are among the advanced quality traits that are being investigated.

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Properties of Citrate-stimulated Starch Synthesis Catalyzed by Starch Synthase I of Developing Maize Kernels

Cited by 59 publications

References 11 publications

Protein Phosphorylation in Amyloplasts Regulates Starch Branching Enzyme Activity and Protein–Protein Interactions

Protein Phosphorylation in Amyloplasts Regulates Starch Branching Enzyme Activity and Protein–Protein Interactions

Selective Measurement of Starch Synthesizing Enzymes in Permeabilized Potato Tuber Slices

Genetic Engineering, Plants

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