Isolation and characterization of the gene encoding the starch debranching enzyme limit dextrinase from germinating barley

Kristensen, Michael; Lok, Finn; Planchot, Véronique; Svendsen, Ib; Leah, Robert; Svensson, Birte

doi:10.1016/s0167-4838(99)00077-1

Cited by 54 publications

(20 citation statements)

References 27 publications

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“…Three different ISA cDNA sequences, one full and two partial, were identified, while one partial sequence was homologous with PUL cDNA (Burton et al, 1999(Burton et al, , 2002a. We did not find another PUL gene (Kristensen et al, 1999) among the seed-specific ESTs, possibly because of its preferential expression during seed germination.…”

Section: Localization Of Starch In the Developing Barley Grainmentioning

confidence: 67%

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Borisjuk²,

et al. 2009

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Barley (Hordeum vulgare) grains synthesize starch as the main storage compound. However, some starch is degraded already during caryopsis development. We studied temporal and spatial expression patterns of genes coding for enzymes of starch synthesis and degradation. These profiles coupled with measurements of selected enzyme activities and metabolites have allowed us to propose a role for starch degradation in maternal and filial tissues of developing grains. Early maternal pericarp functions as a major short-term starch storage tissue, possibly ensuring sink strength of the young caryopsis. Gene expression patterns and enzyme activities suggest two different pathways for starch degradation in maternal tissues. One pathway possibly occurs via a-amylases 1 and 4 and b-amylase 1 in pericarp, nucellus, and nucellar projection, tissues that undergo programmed cell death. Another pathway is deducted for living pericarp and chlorenchyma cells, where transient starch breakdown correlates with expression of chloroplast-localized b-amylases 5, 6, and 7, glucan, water dikinase 1, phosphoglucan, water dikinase, isoamylase 3, and disproportionating enzyme. The suite of genes involved in starch synthesis in filial starchy endosperm is much more complex than in pericarp and involves several endosperm-specific genes. Transient starch turnover occurs in transfer cells, ensuring the maintenance of sink strength in filial tissues and the reallocation of sugars into more proximal regions of the starchy endosperm. Starch is temporally accumulated also in aleurone cells, where it is degraded during the seed filling period, to be replaced by storage proteins and lipids.

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Section: Localization Of Starch In the Developing Barley Grainmentioning

confidence: 67%

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Borisjuk²,

et al. 2009

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“…Biochemical studies established the presence in the endosperm of four starch-degrading enzymes, α-amylase, β-amylase, DBE (specifically LDA), and α-glucosidase (maltase; EC: 3.2.1.3), and their properties and structurefunction relationships have been studied in detail (e.g., 10,40,76,91). However, relatively little is known about the importance of each of the enzymes in the process of starch degradation, in part because of the difficulty of manipulating (92) their levels independently and in a controlled manner.…”

Section: Differences In Starch Degradation Between Leaves and Cereal mentioning

confidence: 99%

Starch: Its Metabolism, Evolution, and Biotechnological Modification in Plants

Zeeman

Koßmann

Smith³

2010

Annu. Rev. Plant Biol.

902

811

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Starch is the most widespread and abundant storage carbohydrate in plants. We depend upon starch for our nutrition, exploit its unique properties in industry, and use it as a feedstock for bioethanol production. Here, we review recent advances in research in three key areas. First, we assess progress in identifying the enzymatic machinery required for the synthesis of amylopectin, the glucose polymer responsible for the insoluble nature of starch. Second, we discuss the pathways of starch degradation, focusing on the emerging role of transient glucan phosphorylation in plastids as a mechanism for solubilizing the surface of the starch granule. We contrast this pathway in leaves with the degradation of starch in the endosperm of germinated cereal seeds. Third, we consider the evolution of starch biosynthesis in plants from the ancestral ability to make glycogen. Finally, we discuss how this basic knowledge has been utilized to improve and diversify starch crops.

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“…A single gene encoding limit dextrinase (LD; EC 3.2.1.41) is expressed in the aleurone layer (Burton et al 1999;Kristensen et al 1999) and may be released into the endosperm (Lee and Pyler 1984). LD activity is low compared with that of other starch hydrolases (MacGregor et al 1999) and, as a result, limit dextrins persist in brewersÕ and distillersÕ worts (Enevoldsen and Bathgate 1969;Bringhurst et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Limit dextrinase from germinating barley has endotransglycosylase activity, which explains its activation by maltodextrins

McDougall¹,

Ross²,

Swanston³

et al. 2004

Planta

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Limit dextrinase (EC 3.2.1.41) from germinating barley (Hordeum vulgare L) can be activated by millimolar concentrations of linear maltodextrins with a degree of polymerisation > or = 2. The activation was assay-dependent; it was detected using assays based on the solubilisation of cross-linked dyed pullulan but not in assays that directly measured cleavage events such as the formation of new reducing termini. This strongly suggested that maltodextrins did not increase the catalytic rate of limit dextrinase i.e. this is not a true activation. On the other hand, considerable activation was noted in assays that measured pullulan degradation by reduction in viscosity. Taken together, this suggested that maltodextrins altered the mode of action of limit dextrinase, causing more rapid decreases in viscosity or greater solubilisation of dye-linked pullulan fragments per cleavage event. The proposed mechanism of activation by alteration in action pattern was reminiscent of initial work in the discovery of xyloglucan endotransglycosylase. Therefore, the ability of limit dextrinase to catalyse transglycosylation reactions into pullulan was tested and confirmed by an assay based on the incorporation of a fluorescently labelled maltotriose derivative into higher-molecular-weight products. The transglycosylation reaction was dependent on limit dextrinase activity and was enhanced in more highly purified preparations of limit dextrinase. Transglycosylation was inhibited by unlabelled maltotriose. How transglycosylation accounts for the apparent activation of limit dextrinase by maltodextrins and the physiological relevance of this novel reaction are discussed.

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Isolation and characterization of the gene encoding the starch debranching enzyme limit dextrinase from germinating barley

Cited by 54 publications

References 27 publications

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Starch: Its Metabolism, Evolution, and Biotechnological Modification in Plants

Limit dextrinase from germinating barley has endotransglycosylase activity, which explains its activation by maltodextrins

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