scholarly journals ‘Slipped Sandwich’ Model for Chitin and Chitosan Perception in Arabidopsis

2018 ◽  
Vol 31 (11) ◽  
pp. 1145-1153 ◽  
Author(s):  
Ekaterina Gubaeva ◽  
Airat Gubaev ◽  
Rebecca L. J. Melcher ◽  
Stefan Cord-Landwehr ◽  
Ratna Singh ◽  
...  
Keyword(s):  
Oxidative Burst ◽  
Sliding Mode ◽  
Higher Plants ◽  
Induced Defense ◽  
Degree Of Polymerization ◽  
Receptor Complexes ◽  
Defense Reactions ◽  
Binding Groove ◽  
Chitin And Chitosan ◽  
Sandwich Model

Chitin, a linear polymer of N-acetyl-d-glucosamine, and chitosans, fully or partially deacetylated derivatives of chitin, are known to elicit defense reactions in higher plants. We compared the ability of chitin and chitosan oligomers and polymers (chitin oligomers with degree of polymerization [DP] 3 to 8; chitosan oligomers with degree of acetylation [DA] 0 to 35% and DP 3 to 15; chitosan polymers with DA 1 to 60% and DP approximately 1,300) to elicit an oxidative burst indicative of induced defense reactions in Arabidopsis thaliana seedlings. Fully deacetylated chitosans were not able to trigger a response; elicitor activity increased with increasing DA of chitosan polymers. Partially acetylated chitosan oligomers required a minimum DP of 6 and at least four N-acetyl groups to trigger a response. Invariably, elicitation of an oxidative burst required the presence of the chitin receptor AtCERK1. Our results as well as previously published studies on chitin and chitosan perception in plants are best explained by a new general model of LysM-containing receptor complexes in which two partners form a long but off-set chitin-binding groove and are, thus, dimerized by one chitin or chitosan molecule, sharing a central GlcNAc unit with which both LysM domains interact. To verify this model and to distinguish it from earlier models, we assayed elicitor and inhibitor activities of selected partially acetylated chitosan oligomers with fully defined structures. In contrast to the initial ‘continuous groove’, the original ‘sandwich’, or the current ‘sliding mode’ models for the chitin/chitosan receptor, the here-proposed ‘slipped sandwich’ model—which builds on these earlier models and represents a consensus combination of these—is in agreement with all experimental observations.

scholarly journals Chitosan perception in Arabidopsis requires the chitin receptor AtCERK1 suggesting an improved model for receptor structure and function

2017 ◽  
Author(s):  
Ekaterina Gubaeva ◽  
Airat Gubaev ◽  
Rebecca Melcher ◽  
Stefan Cord-Landwehr ◽  
Ratna Singh ◽  
...  
Keyword(s):  
Oxidative Burst ◽  
Sliding Mode ◽  
Higher Plants ◽  
Induced Defense ◽  
Degree Of Polymerization ◽  
Receptor Complexes ◽  
Defense Reactions ◽  
Degree Of Acetylation ◽  
Chitin And Chitosan ◽  
Chitin Receptor

AbstractChitin, a linear polymer of N-acetyl-D-glucosamine, and chitosans, fully or partially deacetylated derivatives of chitin, are known to elicit defense reactions in higher plants. We compared the ability of chitin and chitosan oligomers and polymers (chitin oligomers with degree of polymerization 3 to 8; chitosan oligomers with degree of acetylation 0% to 35% and degree of polymerization 3 to 15; chitosan polymers with degree of acetylation 1% to 60% and degree of polymerization ~1300) to elicit an oxidative burst indicative of induced defense reactions in A. thaliana seedlings. Fully deacetylated chitosans were not able to trigger a response; elicitor activity increased with increasing degree of acetylation of chitosan polymers. Partially acetylated chitosan oligomers required a minimum degree of polymerization of 6 and at least four N-acetyl groups to trigger a response. Invariably, elicitation of an oxidative burst required the presence of the chitin receptor AtCERK1. Our results as well as previously published studies on chitin and chitosan perception in plants are best explained by a new general model of LysM-containing receptor complexes where two partners form a long, but off-set chitin-binding groove and are, thus, dimerized by one chitin or chitosan molecule, sharing a central GlcNAc unit with which both LysM domains interact. To verify this model and to distinguish it from earlier models, we assayed elicitor and inhibitor activities of selected partially acetylated chitosan oligomers with fully defined structures. In contrast to the initial “continuous groove”, the original “sandwich”, or the current “sliding mode” models for the chitin/chitosan receptor, the here proposed “slipped sandwich” model - which builds on these earlier models and represents a consensus combination of these - is in agreement with all experimental observations.

scholarly journals The Endopolygalacturonase 1 from Botrytis cinerea Activates Grapevine Defense Reactions Unrelated to Its Enzymatic Activity

2003 ◽  
Vol 16 (6) ◽  
pp. 553-564 ◽  
Author(s):  
Benoît Poinssot ◽  
Elodie Vandelle ◽  
Marc Bentéjac ◽  
Marielle Adrian ◽  
Caroline Levis ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Calcium Influx ◽  
Active Oxygen Species ◽  
Degree Of Polymerization ◽  
Mass Spectrometry Analysis ◽  
Gene Transcript ◽  
Transcript Accumulation ◽  
Spectrometry Analysis ◽  
Defense Reactions

A purified glycoprotein from Botrytis cinerea(strain T4), identified as endopolygalacturonase 1 (T4BcPG1) by mass spectrometry analysis, has been shown to activate defense reactions in grapevine (Vitis vinifera cv. Gamay). These reactions include calcium influx, production of active oxygen species, activation of two mitogen-activated protein kinases, defense gene transcript accumulation, and phytoalexin production. Most of these defense reactions were also activated in grapevine in response to purified oligogalacturonides (OGA) with a degree of polymerization of 9 to 20. In vivo, these active OGA might be a part of the released products resulting from endopolygalacturonase activity on plant cell walls. Nevertheless, the intensity and kinetics of events triggered by OGA were very different when compared with T4BcPG1 effects. Moreover, chemical treatments of T4BcPG1 and desensitization assays have allowed us to discriminate enzymatic and elicitor activities, indicating that elicitor activity was not due to released oligogalacturonides. Thus, BcPG1 should be considered as both an avirulence and a virulence factor. The role of the secreted BcPG1 in the pathogenicity of Botrytis cinerea is discussed.

scholarly journals Deciphering the ChitoCode: fungal chitins and chitosans as functional biopolymers

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Stefan Cord-Landwehr ◽  
Bruno M. Moerschbacher
Keyword(s):  
Higher Plants ◽  
Biological Activities ◽  
Synthetic Methods ◽  
Fungal Cell ◽  
Structural Details ◽  
Food And Feed ◽  
Chitin And Chitosan ◽  
Analytical Tools

AbstractChitins and chitosans are among the most widespread and versatile functional biopolymers, with interesting biological activities and superior material properties. While chitins are evolutionary ancient and present in many eukaryotes except for higher plants and mammals, the natural distribution of chitosans, i.e. extensively deacetylated derivatives of chitin, is more limited. Unequivocal evidence for its presence is only available for fungi where chitosans are produced from chitin by the action of chitin deacetylases. However, neither the structural details such as fraction and pattern of acetylation nor the physiological roles of natural chitosans are known at present. We hypothesise that the chitin deacetylases are generating chitins and chitosans with specific acetylation patterns and that these provide information for the interaction with specific chitin- and chitosan-binding proteins. These may be structural proteins involved in the assembly of the complex chitin- and chitosan-containing matrices such as fungal cell walls and insect cuticles, chitin- and chitosan-modifying and -degrading enzymes such as chitin deacetylases, chitinases, and chitosanases, but also chitin- and chitosan-recognising receptors of the innate immune systems of plants, animals, and humans. The acetylation pattern, thus, may constitute a kind of ‘ChitoCode’, and we are convinced that new in silico, in vitro, and in situ analytical tools as well as new synthetic methods of enzyme biotechnology and organic synthesis are currently offering an unprecedented opportunity to decipher this code. We anticipate a deeper understanding of the biology of chitin- and chitosan-containing matrices, including their synthesis, assembly, mineralisation, degradation, and perception. This in turn will improve chitin and chitosan biotechnology and the development of reliable chitin- and chitosan-based products and applications, e.g. in medicine and agriculture, food and feed sciences, as well as cosmetics and material sciences.

Synthesis of chitosan from chitin of escargot (Achatina fulica)

2004 ◽  
Vol 2 (2) ◽  
pp. 64-68 ◽  
Author(s):  
TRIANA KUSUMANINGSIH ◽  
ABU MASYKUR ◽  
USMAN ARIEF
Keyword(s):  
Molecular Weight ◽  
Mineral Content ◽  
Degree Of Polymerization ◽  
Polymerization Degree ◽  
Achatina Fulica ◽  
X Ray Diffraction ◽  
X Ray ◽  
Degree Of Deacetylation ◽  
Chitin And Chitosan

Chitosan has been made from chitin that was deacetylated from escargot (Achatina fulica). The purification of chitin was done by deproteination, demineralization, and depigmentation. Identification of chitin and chitosan was done by FTIR (Fourier Transform Infrared) and XRD (X-Ray Diffraction). Characterization of chitosan was determined by water and mineral content, molecular weight, polymerization degree and degree of deacetylation. The result of research was obtained chitosan 6,95%, crystal, white brownish color, odorless, 3,26±0,45% water content, 10,11±0,38% mineral content, 889,78 molecular weight average with degree of polymerization 5 and degree of deacetylation 74,78-77,99%.

Ozone-Induced Defense Reactions in Birch (Betula pendula Roth)

1996 ◽  
pp. 265-271
Author(s):  
J. Kangasjärvi ◽  
R. Pellinen ◽  
J. Tuomainen ◽  
R. Julkunen-Tiitto ◽  
M. Kiiskinen
Keyword(s):  
Betula Pendula ◽  
Induced Defense ◽  
Betula Pendula Roth ◽  
Defense Reactions

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

1972 ◽  
Vol 30 ◽  
pp. 230-231
Author(s):  
James Cronshaw ◽  
Jamison E. Gilder
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Higher Plants ◽  
High Surface ◽  
Root Tip ◽  
Animal Cells ◽  
Physiological Processes ◽  
Tip Cells ◽  
Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

The relationship of IGE receptor topography to signaling activity in RBL-2H3 mast cells

1991 ◽  
Vol 49 ◽  
pp. 236-237
Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver
Keyword(s):  
Mast Cells ◽  
Protein A ◽  
Scattered Electron ◽  
Ige Receptor ◽  
Receptor Complexes ◽  
Ige Binding ◽  
Electron Imaging ◽  
Small Clusters ◽  
Relationship Of ◽  
The Relationship

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.

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