Cloning and functional analysis of a cDNA encoding a starch synthase from potato ( Solanum tuberosum L.) that is predominantly expressed in leaf tissue

Koßmann, Jens; Abel, Gernot; Springer, Franziska; Lloyd, J. R.; Willmitzer, Lothar

doi:10.1007/s004250050587

Cited by 71 publications

(54 citation statements)

References 44 publications

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“…Accordingly, the modification of the starch structure by antisense repression of starch synthases or branching enzymes significantly affect the starch phosphate content (20)(21)(22)(23). The actual target structure(s) that are recognized by R1 as a phosphorylation site(s) remain(s) to be identified.…”

Section: Discussionmentioning

confidence: 99%

The starch-related R1 protein is an α-glucan, water dikinase

Ritte

Lloyd

Eckermann

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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To determine the enzymatic function of the starch-related R1 protein it was heterologously expressed in Escherichia coli and purified to apparent homogeneity. Incubation of the purified protein with various phosphate donor and acceptor molecules showed that R1 is capable of phosphorylating glucosyl residues of ␣-glucans at both the C-6 and the C-3 positions in a ratio similar to that occurring naturally in starch. Phosphorylation occurs in a dikinase-type reaction in which three substrates, an ␣-polyglucan, ATP, and H2O, are converted into three products, an ␣-polyglucan-P, AMP, and orthophosphate. The use of ATP radioactively labeled at either the ␥ or ␤ positions showed that solely the ␤ phosphate is transferred to the ␣-glucan. The apparent Km of the R1 protein for ATP was calculated to be 0.23 M and for amylopectin 1.7 mg⅐ml ؊1 . The velocity of in vitro phosphorylation strongly depends on the type of the glucan. Glycogen was an extremely poor substrate; however, the efficiency of phosphorylation strongly increased if the glucan chains of glycogen were elongated by phosphorylase. Mg 2؉ ions proved to be essential for activity. Incubation of R1 with radioactively labeled ATP in the absence of an ␣-glucan showed that the protein phosphorylates itself with the ␤, but not with the ␥ phosphate. Autophosphorylation precedes the phosphate transfer to the glucan indicating a ping-pong reaction mechanism.S tarch is the storage carbohydrate most widely distributed in the plant kingdom. In storage organs it serves as a long-term carbon reserve, whereas in photosynthetically competent tissues it is transiently accumulated to provide both reduced carbon and energy during periods unfavorable for photosynthesis. Starch consists of essentially linear (amylose) and highly branched (amylopectin) glucose polymers that are arranged as semicrystalline particles, the starch granules. Amylopectin from many sources contains phosphate-monoesters that are covalently bound at the C6 and C3 positions of the glucosyl residues (1). In potato tuber starch Ϸ0.1-0.5% of the glucose moieties are phosphorylated. The amount of phosphate monoesters in starch strongly influences its physicochemical properties (2) and, therefore, affects the ability of different starches to be used by industry.In potato tubers the starch-bound phosphate comprises a significant proportion of the total tuber phosphate content, but its function in starch metabolism is not clear. The same holds true for the biochemical reaction(s) leading to the formation of the starch phosphate monoesters. A protein (designated as R1) has been recently identified using a proteomic approach, and circumstantial evidence suggests that it is involved in the phosphorylation of starch (2, 3). The C-terminal sequence of the R1 protein shows some homology to bacterial PEP synthases (pyruvate, water dikinase EC 2.7.9.2), which transfer phosphate from ATP in a dikinase reaction to pyruvate and water. Antisense repression of R1 in potato leads to a strong reduction in the amount of starch-boun...

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Section: Discussionmentioning

confidence: 99%

The starch-related R1 protein is an α-glucan, water dikinase

Ritte

Lloyd

Eckermann

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

294

248

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“…However, the complete absence of SSI has no effect on the size and shape of seeds and starch granules or the crystallinity of endosperm starch, suggesting that other SS isoforms are capable of partly compensating for the absence of SSI function [51]. Kossmann et al [104] reported that the reduction of potato SSI in antisense plants did not lead to detectable changes in starch structure. They suggested that this lack of change was because potato SSI was predominantly expressed in leaves and only represented a minor activity in potato tubers, where SSII and SSIII were the major isoforms expressed.…”

Section: Soluble Starch Synthasementioning

confidence: 99%

Causal Relations Among Starch Biosynthesis, Structure, and Properties

Wang

Henry

Gilbert

2014

Springer Science Reviews

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Starch, an important carbohydrate with widespread applications in human foods, animal feeds, and many industrial products, is synthesized by plants by the action of a complex system involving many enzymes. The differing activities of these enzymes contribute to variations in starch structure among different plant species, botanical organs, and genetic backgrounds, and thus affect the physicochemical properties and end-use functions of starch. The demand for starches with particular functional properties is increasing, but the ability to produce novel starches is still limited. Starches with specific properties can potentially be produced by biotechnical modification of the starch biosynthetic pathway; however, this requires further understanding of the starch biosynthesis-structureproperties relationships. This review summarizes the state of the art in the understanding of these causal relationships: the roles of the main starch-synthesizing enzymes on starch structure, hierarchical structure of starch, advanced molecular structure characterization methods, and impact of starch structure on some functional properties. A better understanding of these relationships among starch biosynthesis, structure, and properties provides direction for genetic modification and targeted breeding programs to produce starch with desired characteristics.

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“…Kossmann et al (1999) reported that the reduction of potato SSI in antisense plants did not lead to any detectable changes in starch structure in the tuber, since in potato SSI is predominantly expressed in leaves and only to a lower extent in the tuber where SSII and SSIII are the major isozymes expressed. In Arabidopsis mutants defective in SSI (Delvalle et al, 2005), which is one of the major isozymes in its leaves, the chain-length distribution of amylopectin showed a decrease in DP 8 to 12 branches and an increase in DP 17 to 20 branches.…”

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confidence: 99%

Function and Characterization of Starch Synthase I Using Mutants in Rice

et al. 2006

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(A.M., H.H.) Four starch synthase I (SSI)-deficient rice (Oryza sativa) mutant lines were generated using retrotransposon Tos17 insertion. The mutants exhibited different levels of SSI activities and produced significantly lower amounts of SSI protein ranging from 0% to 20% of the wild type. The mutant endosperm amylopectin showed a decrease in chains with degree of polymerization (DP) 8 to 12 and an increase in chains with DP 6 to 7 and DP 16 to 19. The degree of change in amylopectin chain-length distribution was positively correlated with the extent of decrease in SSI activity in the mutants. The structural changes in the amylopectin increased the gelatinization temperature of endosperm starch. Chain-length analysis of amylopectin in the SSI band excised from native-polyacrylamide gel electrophoresis/SS activity staining gel showed that SSI preferentially synthesized DP 7 to 11 chains by elongating DP 4 to 7 short chains of glycogen or amylopectin. These results show that SSI distinctly generates DP 8 to 12 chains from short DP 6 to 7 chains emerging from the branch point in the A or B 1 chain of amylopectin. SSI seemingly functions from the very early through the late stage of endosperm development. Yet, the complete absence of SSI, despite being a major SS isozyme in the developing endosperm, had no effect on the size and shape of seeds and starch granules and the crystallinity of endosperm starch, suggesting that other SS enzymes are probably capable of partly compensating SSI function. In summary, this study strongly suggested that amylopectin chains are synthesized by the coordinated actions of SSI, SSIIa, and SSIIIa isoforms.

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Cloning and functional analysis of a cDNA encoding a starch synthase from potato ( Solanum tuberosum L.) that is predominantly expressed in leaf tissue

Cited by 71 publications

References 44 publications

The starch-related R1 protein is an α-glucan, water dikinase

The starch-related R1 protein is an α-glucan, water dikinase

Causal Relations Among Starch Biosynthesis, Structure, and Properties

Function and Characterization of Starch Synthase I Using Mutants in Rice

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