title: Xyloglucan oligosaccharides cause cell wall loosening by enhancing xyloglucan endotransglucosylase/hydrolase activity in azuki bean epicotyls.
abstract: Addition of xyloglucan-derived oligosaccharides shifted the wall-bound xyloglucans to a lower molecular mass distribution and increased the cell wall extensibility of the native epidermal tissue strips isolated from azuki bean (Vigna angularis) epicotyls. To ascertain the mechanism of oligosaccharide function, we examined the action of a xyloglucan endotransglucosylase/hydrolase (XTH) showing both endotransglucosylase and endohydrolase activities, isolated from azuki bean epicotyl cell walls, in the presence of xyloglucan oligosaccharides. The addition of xyloglucan oligosaccharides enhanced the xyloglucan-degrading activity of XTH against isolated xyloglucan substrates. When the methanol-fixed epidermal tissue strips were incubated with XTH, the molecular mass of wall-bound xyloglucans was decreased and the cell wall extensibility increased markedly in the presence of the oligosaccharides. These results suggest that xyloglucan oligosaccharides stimulate the degradation of xyloglucans by enhancing the XTH activity within the cell wall architecture, thereby increasing the cell wall extensibility in azuki bean epicotyls.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, 558-8585 Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kaku
authors.forename: Akira
authors.initials: A
authors.lastname: Tabuchi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Wakabayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hoson
mesh_terms: D002473:Cell Wall / Q000187:drug effects / Q000201:enzymology*; D007887:Fabaceae / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005936:Glucans / Q000378:metabolism* / Q000494:pharmacology; D016695:Glycosyltransferases / Q000378:metabolism*; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D014990:Xylans / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D005936:Glucans; D014990:Xylans; C029353:xyloglucan; D016695:Glycosyltransferases; C473049:xyloglucan - xyloglucosyltransferase