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The aim of this work was to develop a biochemical approach to study (1-->3)-beta-D-glucan (callose) biosynthesis using suspension cultures of Arabidopsis thaliana. Optimal conditions for in vitro synthesis of callose corresponded to an assay mixture containing 50 mM Mops buffer, pH 6.8, 1 mM
Successful defence of plants against colonisation by fungal pathogens depends on the ability to prevent initial penetration of the plant cell wall. Here we report that the pathogen-induced (1,3)-β-glucan cell wall polymer callose, which is deposited at sites of attempted penetration, directly
The genome of Arabidopsis thaliana encodes three glucan, water dikinases. Glucan, water dikinase 1 (GWD1; EC 2.7.9.4) and phosphoglucan, water dikinase (PWD; EC 2.7.9.5) are chloroplastic enzymes, while glucan, water dikinase 2 (GWD2) is cytosolic. Both GWDs and PWD catalyze the addition of
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
Thermotoga maritima XynA is an extremely thermostable modular enzyme with five domains (A1-A2-B-C1-C2). Its catalytic domain (-B-) is flanked by duplicated non-catalytic domains. The C-terminal repeated domains represent cellulose-binding domains (CBDs). Xylanase domains related to the N-terminal
The formation of intermediary glucans, mature starch, and phytoglycogen was studied using leaves of Arabidopsis thaliana wild type and dbe mutant, which lacks plastidic isoamylase (Zeeman, S. C., Umemoto, T., Lue, W. L., Au-Yeung, P., Martin, C., Smith, A. M., and Chen, J. (1998) Plant Cell 10,
Chlamydomonas reinhardtii is the best known unicellular green alga model which has long been used to investigate all kinds of cellular processes, including starch metabolism. Here we identified and characterized a novel enzyme, ChlreSEX4, orthologous to glucan phosphatase SEX4 from Arabidopsis
Laminarin, a beta-1,3 glucan with single beta-glucose branches at position 6, was chemically sulfated to produce PS3 with a degree of sulfation of 2.4. PS3 has previously been shown to activate the salicylic acid (SA) signaling pathway in infiltrated tobacco and Arabidopsis thaliana leaf tissues.
Highly purified tonoplast and plasma membrane vesicles were isolated from microsomes of Arabidopsis thaliana by preparative free-flow electrophoresis. The most electronegative fractions were identified as tonoplast using nitrate-inhibited Mg2+-ATPase as enzyme marker. The least electronegative
The cytosolic level of inorganic pyrophosphate (PPi) is finely regulated, with PPi hydrolyzed primarily by the vacuolar H+-pyrophosphatase (H+-PPase, VHP1/FUGU5/AVP1) and secondarily by five cytosolic soluble pyrophosphatases (sPPases; PPa1-PPa5) in Arabidopsis thaliana.
Glycogen and starch are the major energy storage compounds in most living organisms. The metabolic pathways leading to their synthesis involve the action of several enzymes, among which glycogen synthase (GS) or starch synthase (SS) catalyze the elongation of the alpha-1,4-glucan backbone. At least
The Arabidopsis thaliana nonhost resistant 2B (AtNHR2B) is involved in plant defense responses by mediating the deposition of the ß-1,3-glucan polymer callose to the cell wall in response to bacterial pathogens. Despite having a critical role in plant immunity, the exact mechanism of how this
Cellulose microfibrils containing crystalline beta-1,4-glucan provide the major structural framework in higher-plant cell walls. Genetic analyses of Arabidopsis thaliana now link specific genes to plant cellulose production just as was achieved some years earlier with bacteria. Cellulose-deficient
In Arabidopsis thaliana (Arabidopsis) treated with the harpin protein HrpN Ea, resistance to the green peach aphid Myzus persicae, a generalist phloem-feeding insect, develops with induced expression of the AtMYB44 gene. Special GLUCAN SYNTHESIS-LIKE (GSL) genes and beta-1,3-glucan callose play an
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