alpha glucan/arabidopsis

Starch phosphorylation catalysed by the alpha-glucan, water dikinases (GWD) has profound effects on starch degradation in plants. The Arabidopsis thaliana genome encodes three isoforms of GWD, two of which are localized in the chloroplast and are involved in the degradation of transient starch. The

Cold-induced soluble sugar accumulation enhances the degree of freezing tolerance in various cold-hardy plants including Arabidopsis (Arabidopsis thaliana), where soluble sugars accumulate in only a few hours at 2 degrees C. Hence, along with photosynthesis, starch degradation might play a

To identify potential regulators of photoassimilate partitioning, we screened for rice mutant plants that accumulate high levels of starch in the leaf blades, and a mutant line leaf starch excess 1 (LSE1) was obtained and characterized. The starch content in the leaf blades of LSE1 was more than

An Arabidopsis thaliana gene encoding a homologue of the potato alpha-glucan, water dikinase GWD, previously known as R1, was identified by screening the Arabidopsis genome and named AtGWD3. The AtGWD3 cDNA was isolated, heterologously expressed and the protein was purified to apparent homogeneity

Transitory starch of leaves is broken down hydrolytically, making maltose the predominant form of carbon exported from chloroplasts at night. Maltose metabolism in the cytoplasm of Escherichia coli requires amylomaltase (MalQ) and maltodextrin phosphorylase (MalP). Possible orthologs of MalQ and

The biochemical function of the Laforin-like dual-specific phosphatase AtSEX4 (EC 3.1.3.48) has been studied. Crystalline maltodextrins representing the A- or the B-type allomorph were prephosphorylated using recombinant glucan, water dikinase (StGWD) or the successive action of both plastidial

Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity

To study the role of the plastidial alpha-glucan phosphorylase in starch metabolism in the leaves of Arabidopsis, two independent mutant lines containing T-DNA insertions within the phosphorylase gene were identified. Both insertions eliminate the activity of the plastidial alpha-glucan

The plant genome encodes at least two distinct and evolutionary conserved plastidial starch-related dikinases that phosphorylate a low percentage of glucosyl residues at the starch granule surface. Esterification of starch favours the transition of highly ordered α-glucans to a less ordered state

For quantification of alpha-glucan, water dikinase (GWD) activity in crude extracts of plant tissues a radio-labeling assay was established that uses soluble starch and (33)P-labeled ATP as phosphate acceptor and donor, respectively. A constant rate of starch labeling was observed only if the ATP

In Arabidopsis (Arabidopsis thaliana) leaves, starch is synthesized during the day and degraded at night to fuel growth and metabolism. Starch is degraded primarily by β-amylases, liberating maltose, but this activity is preceded by glucan phosphorylation and is accompanied by

Starch Branching Enzymes (SBE) catalyze the formation of α(1 → 6) branching points on starch polymers: amylopectin and amylose. SBEs are classified in two groups named type 1 and 2. Both types are present in the entire plant kingdom except in some species such as Arabidopsis thaliana that expresses

BACKGROUND Natural accessions of Arabidopsis thaliana are a well-known system to measure levels of intraspecific genetic variation. Leaf starch content correlates negatively with biomass. Starch is synthesized by the coordinated action of many (iso)enzymes. Quantitatively dominant is the repetitive

Starch is a water-insoluble, Glc-based biopolymer that is used for energy storage and is synthesized and degraded in a diurnal manner in plant leaves. Reversible phosphorylation is the only known natural starch modification and is required for starch degradation in planta. Critical to starch energy

Biosynthesis of starch is catalyzed by a cascade of enzymes. The activity of a large number of these enzymes depends on interaction with polymeric substrates via carbohydrate binding sites, which are situated outside of the catalytic site and its immediate surroundings including the