Pea Xyloglucan and Cellulose

Hayashi, Takahisa; Marsden, Margery P. F.; Delmer, Deborah P.

doi:10.1104/pp.83.2.384

Cited by 182 publications

(80 citation statements)

References 12 publications

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“…Xyloglucans (XGs) are a class of hemicellulose molecules which bind with a high specificity and affinity to cellulose microfibrils, thereby producing a cell shapedetermining cellulose-XG network. In vitro reconstitution studies of XG and cellulose have shown that XG binds efficiently to cellulose even in the presence of other cell wall ~-glucans, arabinogalactans and pectins (Hayashi et al, 1987). It has also been shown that XG can compete successfully with the glucan chains of cellulose for binding since, when present in the culture medium, it leads to the formation of smaller-diameter Acetobacter cellulose microfibrils (Atalla et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

1997

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SummaryCross-links between cellulose microfibrils and xyloglucan (XG) molecules play a major role in defining the structural properties of plant cell walls and the regulation of growth and development of dicotyledonous plants. How these cross-links are established and how they are regulated has yet to be determined. In a previous study, preliminary data were presented which suggested that the different sidechains of XG may play a role in controlling cellulose microfibriI-XG interactions. In this study, this question is addressed directly by analyzing to what extent the different sidechains of pea cell wall XG and nasturtium seed storage XG affect their binding to cellulose microfibrils. Of particular importance to this study are the chemical data indicating that pea XG possesses a trisaccharide sidechain, which is not found in nasturtium XG. To this end, conformational dynamic simulations have been used to predict whether oligosaccharides representative of pea and nasturtium XG can adopt a hypothesized cellulosebinding conformation and which of these XGs exhibits a preferential ability to bind cellulose. Extensive analysis of the conformational forms populated during 300 K and high-temperature Monte Carlo simulations established that a planar, sterically accessible, glucan backbone is essential for optimal cellulose-binding. For the trisaccharide sidechain-containing oligosaccharide as found in pea XG, sidechain orientation appeared to regulate the gradual acquisition of this hypothesized cellulose binding conformation. Thus, conformational forms were identified that included the twisted backbone (non-planar) putative solution form of XG, forms in which the trisaccharide sidechain orientation enables increased backbone planarity and steric accessibility, and finally a planar, sterically accessible, backbone. By applying these conformational requirements for cellulose binding, it has been Received 25 May 1996; revised 11 October 1996; accepted 12 November 1996. *For correspondence (fax +1 303 492 7744; e-mail levy@spot.colorado.edu).determined that pea XG possesses a two-to threefold occurrence of the cellulose binding conformation than nasturtium XG. Based on this finding, it was predicted that pea XG would bind to cellulose at a higher rate than nasturtium XG. In vitro binding assays showed that pea XG-avicel binding does indeed occur at a twofold higher rate than nasturtium XG-avicel binding. The enhanced ability of pea cell wall XG over nasturtium seed storage XG to associate with cellulose is consistent with a structural role of the former during epicotyl growth where efficient association with cellulose is a requirement. In contrast, the relatively low ability of nasturtium XG to bind cellulose is consistent with the need to enhance the accessibility of this polymer to glycanases during germination. These findings suggest potential roles for XG sidechain substitution, enabling XG to function in a variety of different biological contexts.

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Section: Introductionmentioning

confidence: 99%

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

1997

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“…Xylan, which is a hemicellulose with ability to hydrogen bond with cellulose (Hayashi et a/., 1987;Uhlin, 1990), is probably absent from the thickenings of treated TEs because it cannot integrate permanently into the wall structure of suspension culture cells without binding to cellulose microfibrils. This possibility is consistent with the demonstration that cellulose-depleted primary walls of DCB-adapted suspension cells lack xyloglucan, the predominant hemicellulose in many primary cell walls.…”

Section: Dcb-and Isoxaben-treated Tes Deposit Some Cell Wall Componenmentioning

confidence: 99%

Dispersed lignin in tracheary elements treated with cellulose synthesis inhibitors provides evidence that molecules of the secondary cell wall mediate wall patterning

et al. 1992

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SummaryMesophyll cells of Zinnia elegans var. Envy that had been induced to differentiate into tracheary elements (TEs) in suspension culture were treated with the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB). The deposition of cellulose into the patterned secondary cell wall thickenings typical of TEs was inhibited as demonstrated by reduced incorporation of [14C]glucose into acetichitric insoluble material and absence of cellulose detectable by fluorescence after staining with Tinopal LPW, polarization optics, or labeling with a specific cellulase. Respiration as indicated by release of I4CO2 was inhibited to a much lesser extent, supporting a selective mechanism of action of DCB on the cellulose biosynthetic pathway. Patterned secondary cell wall thickenings were deposited in DCB-treated TEs, but these were smaller and less regularly shaped than those of control TEs. These cellulose-depleted thickenings lacked another abundant component of normal thickenings, the hemicellulose xylan, as indicated by absence of labeling with a specific xylanase or an antibody to xylan. DCBtreated TEs also showed dispersed lignin after staining with phloroglucinol, whereas control TEs contained lignin specifically localized to the secondary cell wall thickenings. Isoxaben, another recently described inhibitor of synthesis of acetichitric insoluble cell wall material (putatively cellulose), caused the same absence of detectable cellulose and xylan in the thickenings and dispersed lignin. These data suggest that: (i) the localization of lignin is ultimately dependent on the localization of cellulose; (ii) normal patterned wall assembly in TEs occurs in a self-perpetuating cascade in which some molecules of the secondary cell wall mediate patterning of others.

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“…Some xylosyl residues are substituted at 0 -2 with p-D-galactopyranosyl residues, and some of these P-D-galactopyranosyl residues are themselves substituted with a-L-fucopyranosyl residues. Xyloglucans hydrogen bond to the cellulose microfibrils in the wall (Valent and Albersheim, 1974), thereby probably cross-linking them (Hayashi et al, 1987(Hayashi et al, , 1994aHayashi 1989;Fry, 198913). Modification of these cellulosexyloglucan cross-links is most likely a key step in controlling cell extensibility.…”

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confidence: 99%

The Arabidopsis TCH4 Xyloglucan Endotransglycosylase (Substrate Specificity, pH Optimum, and Cold Tolerance)

1997

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Xyloglucan endotransglycosylases (XETs) modify a major component of the plant cell wall and therefore may play critical roles in generating tissue properties and influencing morphogenesis. An XET-related gene family exists in Arabidopsis thaliana, the members of which show differential regulation of expression. TCH4 expression is rapidly regulated by mechanical stimuli, temperature shifts, light, and hormones. As a first step in determining whether Arabidopsis XET-related proteins have distinct properties, we produced recombinant TCH4 protein in bacteria and determined its enzymatic characteristics. TCH4 specifically transglycosylates only xyloglucan. The enzyme prefers to transfer a portion of a donor polymer onto another xyloglucan polymer (acceptor); TCH4 will also utilize xyloglucan-derived oligosaccharides as acceptors but discriminates between differentially fucosylated oligosaccharides. TCH4 is most active at pH 6.0 to 6.5 and is surprisingly coldtolerant with an optimum of 1 2 to 18°C. TCH4 activity is enhanced by urea and bovine serum albumin, but not cations, reducing agents, or carboxymethylcellulose. These studies indicate that TCH4 i s specific for xyloglucan, but that the molecular mass and the fucosyl content of the substrates influence enzymatic reaction rates.

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Pea Xyloglucan and Cellulose

Cited by 182 publications

References 12 publications

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

Dispersed lignin in tracheary elements treated with cellulose synthesis inhibitors provides evidence that molecules of the secondary cell wall mediate wall patterning

The Arabidopsis TCH4 Xyloglucan Endotransglycosylase (Substrate Specificity, pH Optimum, and Cold Tolerance)

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