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https://hdl.handle.net/2440/43660
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Type: | Journal article |
Title: | A barley xyloglucan xyloglucosyl transferase covalently links xyloglucan, cellulosic substrates, and (1 3;1 4)-β-D-glucans |
Other Titles: | A barley xyloglucan xyloglucosyl transferase covalently links xyloglucan, cellulosic substrates, and (1 3;1 4)-beta-D-glucans |
Author: | Hrmova, M. Farkas, V. Lahnstein, J. Fincher, G. |
Citation: | Journal of Biological Chemistry, 2007; 282(17):12951-12962 |
Publisher: | Amer Soc Biochemistry Molecular Biology Inc |
Issue Date: | 2007 |
ISSN: | 0021-9258 1083-351X |
Statement of Responsibility: | Maria Hrmova, Vladimir Farkas, Jelle Lahnstein, and Geoffrey B. Fincher |
Abstract: | Molecular interactions between wall polysaccharides, which include cellulose and a range of noncellulosic polysaccharides such as xyloglucans and (1,3;1,4)-β-d-glucans, are fundamental to cell wall properties. These interactions have been assumed to be noncovalent in nature in most cases. Here we show that a highly purified barley xyloglucan xyloglucosyl transferase HvXET5 (EC 2.4.1.207), a member of the GH16 group of glycoside hydrolases, catalyzes the in vitro formation of covalent linkages between xyloglucans and cellulosic substrates and between xyloglucans and (1,3;1,4)-β-d-glucans. The rate of covalent bond formation catalyzed by HvXET5 with hydroxyethylcellulose (HEC) is comparable with that on tamarind xyloglucan, whereas that with (1,3; 1,4)-β-d-glucan is significant but slower. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analyses showed that oligosaccharides released from the fluorescent HEC:xyloglucan conjugate by a specific (1,4)-β-dglucan endohydrolase consisted of xyloglucan substrate with one, two, or three glucosyl residues attached. Ancillary peaks contained hydroxyethyl substituents (m/z 45) and confirmed that the parent material consisted of HEC covalently linked with xyloglucan. Similarly, partial hydrolysis of the (1,3;1,4)-β-d-glucan:xyloglucan conjugate by a specific (1,3;1,4)-β-d-glucan endohydrolase revealed the presence of a series of fluorescent oligosaccharides that consisted of the fluorescent xyloglucan acceptor substrate linked covalently with 2-6 glucosyl residues. These findings raise the possibility that xyloglucan endo-transglucosylases could link different polysaccharides in vivo and hence influence cell wall strength, flexibility, and porosity. |
Keywords: | Cell Wall Hordeum Glucans Cellulose Glycosyltransferases Xylans Plant Proteins Porosity |
Rights: | Copyright © 2007 by the American Society for Biochemistry and Molecular Biology |
DOI: | 10.1074/jbc.M611487200 |
Published version: | http://www.jbc.org/cgi/content/abstract/282/17/12951 |
Appears in Collections: | Agriculture, Food and Wine publications Aurora harvest |
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