A xyloglucan oligosaccharide‐active, transglycosylating‐D‐glucosidase from the cotyledons of nasturtium (<i>Tropaeolum majus</i> L) seedlings – purification, properties and characterization of a cDNA clone

Crombie, H. J.; Chengappa, Sumant; Hellyer, A.; Reid, J. S. Grant

doi:10.1046/j.1365-313x.1998.00182.x

Cited by 72 publications

(66 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1C), the presence of XXLG in the medium suggests that it is not a good substrate for this activity. A xyloglucan-specific b-galactosidase purified from Copaifera langsdorfii had no activity on XXLG (de Alcântara et al, 1999), and a similar enzyme from T. majus had a much higher activity on XLXG than XXLG (Crombie et al, 1998;de Alcântara et al, 1999). Although these enzymes are involved in xyloglucan mobilization in germinating seeds, our results are consistent with similar substrate specificity for the primary wall b-galactosidase activity in Arabidopsis.…”

Section: Discussionsupporting

confidence: 84%

“…a-Xylosidase activities in both pea (Pisum sativum) and Tropaeolum majus can only remove unsubstituted Xyl residues from the nonreducing end of the molecule (O'Neill et al, 1989;Fanutti et al, 1991). A b-glucosidase is then required to remove the unsubstituted Glc before a-xylosidase can act again (Crombie et al, 1998). b-Galactosidase and a-fucosidase activities are also required for the complete disassembly of the different Arabidopsis oligosaccharides Léonard et al, 2008).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Lack of α-Xylosidase Activity in Arabidopsis Alters Xyloglucan Composition and Results in Growth Defects

et al. 2010

View full text Add to dashboard Cite

Xyloglucan is the main hemicellulose in the primary cell walls of most seed plants and is thought to play a role in regulating the separation of cellulose microfibrils during growth. Xylose side chains block the degradation of the backbone, and a-xylosidase activity is necessary to remove them. Two Arabidopsis (Arabidopsis thaliana) mutant lines with insertions in the a-xylosidase gene AtXYL1 were characterized in this work. Both lines showed a reduction to undetectable levels of a-xylosidase activity against xyloglucan oligosaccharides. This reduction resulted in the accumulation of XXXG and XXLG in the liquid growth medium of Atxyl1 seedlings. The presence of XXLG suggests that it is a poor substrate for xyloglucan b-galactosidase. In addition, the polymeric xyloglucan of Atxyl1 lines was found to be enriched in XXLG subunits, with a concomitant decrease in XXFG and XLFG. This change can be explained by extensive exoglycosidase activity at the nonreducing ends of xyloglucan chains. These enzymes could thus have a larger role than previously thought in the metabolism of xyloglucan. Finally, Atxyl1 lines showed a reduced ability to control the anisotropic growth pattern of different organs, pointing to the importance of xyloglucan in this process. The promoter of AtXYL1 was shown to direct expression to many different organs and cell types undergoing cell wall modifications, including trichomes, vasculature, stomata, and elongating anther filaments.

show abstract

Section: Discussionsupporting

confidence: 84%

mentioning

confidence: 99%

Lack of α-Xylosidase Activity in Arabidopsis Alters Xyloglucan Composition and Results in Growth Defects

et al. 2010

View full text Add to dashboard Cite

show abstract

“…On the basis of these results, together with other studies on the mode of action of the XTH (Edwards et al, 1986;Fanutti et al, 1993), Crombie et al (1998) proposed a model for xyloglucan mobilization in nasturtium. In this model, the four enzymes are thought to work in a concerted fashion, producing Gal, Glc, and Xyl.…”

supporting

confidence: 57%

“…They are (1) xyloglucan-specific endo-b-(1fi4)-D-glucanase or xyloglucan XET (Edwards et al, 1986;Fanutti et al, 1993); (2) a b-galactosidase with high specificity toward xyloglucan (Edwards et al, 1988); (3) a xyloglucan oligosaccharide-specific a-xylosidase or oligoxyloglucan exo-xylohydrolase (Fanutti et al, 1991); and (4) a transglycosylating b-glucosidase (Crombie et al, 1998).…”

mentioning

confidence: 99%

The Control of Storage Xyloglucan Mobilization in Cotyledons of Hymenaea courbaril

et al. 2004

View full text Add to dashboard Cite

Hymenaea courbaril is a leguminous tree species from the neotropical rain forests. Its cotyledons are largely enriched with a storage cell wall polysaccharide (xyloglucan). Studies of cell wall storage polymers have been focused mostly on the mechanisms of their disassembly, whereas the control of their mobilization and the relationship between their metabolism and seedling development is not well understood. Here, we show that xyloglucan mobilization is strictly controlled by the development of first leaves of the seedling, with the start of its degradation occurring after the beginning of eophyll (first leaves) expansion. During the period of storage mobilization, an increase in the levels of xyloglucan hydrolases, starch, and free sugars were observed in the cotyledons. Xyloglucan mobilization was inhibited by shoot excision, darkness, and by treatment with the auxin-transport inhibitor N-1-naphthylphthalamic acid. Analyses of endogenous indole-3-acetic acid in the cotyledons revealed that its increase in concentration is followed by the rise in xyloglucan hydrolase activities, indicating that auxin is directly related to xyloglucan mobilization. Cotyledons detached during xyloglucan mobilization and treated with 2,4-dichlorophenoxyacetic acid showed a similar mobilization rate as in attached cotyledons. This hormonal control is probably essential for the ecophysiological performance of this species in their natural environment since it is the main factor responsible for promoting synchronism between shoot growth and reserve degradation. This is likely to increase the efficiency of carbon reserves utilization by the growing seedling in the understorey light conditions of the rain forest.

show abstract

“…A ␤-galactosidase is active only against XyG oligomers (or the non-reducing terminal oligomer of XyG polymers) and removes solely the middle galactosyl residue. This ␤-galactosidase activity generates an oligomer that becomes accessible to ␣-xylosidases (Fanutti et al, 1991) and ␤-glucosidases (Crombie et al, 1998) that act cooperatively to digest the xylosyl and backbone glucosyl units. However, these activities cannot occur in the absence of XET or XEH activity, and in contrast to the observed results (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Galactose Residues of Xyloglucan Are Essential to Maintain Mechanical Strength of the Primary Cell Walls in Arabidopsis during Growth

et al. 2004

View full text Add to dashboard Cite

In land plants, xyloglucans (XyGs) tether cellulose microfibrils into a strong but extensible cell wall. The MUR2 and MUR3 genes of Arabidopsis encode XyG-specific fucosyl and galactosyl transferases, respectively. Mutations of these genes give precisely altered XyG structures missing one or both of these subtending sugar residues. Tensile strength measurements of etiolated hypocotyls revealed that galactosylation rather than fucosylation of the side chains is essential for maintenance of wall strength. Symptomatic of this loss of tensile strength is an abnormal swelling of the cells at the base of fully grown hypocotyls as well as bulging and marked increase in the diameter of the epidermal and underlying cortical cells. The presence of subtending galactosyl residues markedly enhance the activities of XyG endotransglucosylases and the accessibility of XyG to their action, indicating a role for this enzyme activity in XyG cleavage and religation in the wall during growth for maintenance of tensile strength. Although a shortening of XyGs that normally accompanies cell elongation appears to be slightly reduced, galactosylation of the XyGs is not strictly required for cell elongation, for lengthening the polymers that occurs in the wall upon secretion, or for binding of the XyGs to cellulose.The plant cell wall is continually modified during cell growth and differentiation. The tensile strength of the wall is provided by a dense spool of cellulose microfibrils interlaced with cross-linking glycans (Carpita and Gibeaut, 1993). When plant cells grow, the wall is biochemically "loosened" to permit turgor-driven cell expansion (Cosgrove, 2000). One of the mysteries of cell growth in plants that researchers have pondered for decades is how these interlaced glycans loosen without compromising the tensile strength of the pliant wall.In all dicots and certain monocots, xyloglucans (XyGs) are the principal cellulose tethering molecules, and the loosening of these tethers from the microfibrils provides a physical control point of cell expansion (Cosgrove, 2000). The unique ability of XyG endotransglucosylases (XETs) to cleave XyGs and rejoin the cut ends with new partners suggested a role for these enzyme activities in wall loosening during growth and in the restructuring of cell walls after extension (Nishitani and Tominaga, 1992). (A revised nomenclature has been adopted by consensus of researchers of the XyG endotransglucosylase/ hydrolase gene/protein family [Rose et al., 2002]. The abbreviation XTH refers to any gene/protein of the family regardless of activity of the protein. However, when referring to endotransglucosylase activities, the abbreviation remains XET, and hydrolase activities are abbreviated XEH.) However, the only cell wall proteins proven to be capable of causing extension of isolated walls in vitro under mechanical stress are expansins, which increase wall extensibility under constant stress (McQueen-Mason et al., 1992), and yieldins, which lower the "yield threshold," the minimum stress required that p...

show abstract

A xyloglucan oligosaccharide‐active, transglycosylating‐D‐glucosidase from the cotyledons of nasturtium (Tropaeolum majus L) seedlings – purification, properties and characterization of a cDNA clone

Cited by 72 publications

References 47 publications

Lack of α-Xylosidase Activity in Arabidopsis Alters Xyloglucan Composition and Results in Growth Defects

Lack of α-Xylosidase Activity in Arabidopsis Alters Xyloglucan Composition and Results in Growth Defects

The Control of Storage Xyloglucan Mobilization in Cotyledons of Hymenaea courbaril

The Galactose Residues of Xyloglucan Are Essential to Maintain Mechanical Strength of the Primary Cell Walls in Arabidopsis during Growth

Contact Info

Product

Resources

About