Xyloglucan Endotransglucosylase Activity Loosens a Plant Cell Wall

• Published in: Annals of botany Vol. 100; no. 7; pp. 1467 - 1473
• Main Authors: Van Sandt, Vicky S.T, Suslov, Dmitry, Verbelen, Jean-Pierre, Vissenberg, Kris
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.12.2007; Oxford Publishing Limited (England)
• Subjects: cell expansion; Cell growth; Cell Wall - drug effects; Cell Wall - enzymology; Cell Wall - metabolism; cell wall loosening; Cell walls; Cellulose - metabolism; cellulose microfibrils; cellulose orientation; Enzymes; Epidermal cells; Epidermis; extensiometry; Glucans - metabolism; Glycosyltransferases - genetics; Glycosyltransferases - metabolism; Glycosyltransferases - pharmacology; onion (Allium cepa); Onions - enzymology; Onions - metabolism; Original; Plant cells; Plant Epidermis - drug effects; Plant Epidermis - enzymology; Plant Epidermis - metabolism; Plant growth; Plant physiology; Plants; primary cell wall; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology; Selaginella kraussiana; Selaginellaceae - enzymology; Selaginellaceae - metabolism; Stem cells; XET activity; XTH; Xylans - metabolism; xyloglucan; cell expansion; cellulose microfibrils; primary cell wall; onion; xyloglucan; ); cell wall loosening; extensiometry; XTH; XET activity; cellulose orientation
• ISSN: 0305-7364; 1095-8290
• DOI: 10.1093/aob/mcm248

BACKGROUND AND AIMS: Plant cells undergo cell expansion when a temporary imbalance between the hydraulic pressure of the vacuole and the extensibility of the cell wall makes the cell volume increase dramatically. The primary cell walls of most seed plants consist of cellulose microfibrils tethered mainly by xyloglucans and embedded in a highly hydrated pectin matrix. During cell expansion the wall stress is decreased by the highly controlled rearrangement of the load-bearing tethers in the wall so that the microfibrils can move relative to each other. Here the effect was studied of a purified recombinant xyloglucan endotransglucosylase/hydrolase (XTH) on the extension of isolated cell walls. METHODS: The epidermis of growing onion (Allium cepa) bulb scales is a one-cell-thick model tissue that is structurally and mechanically highly anisotropic. In constant load experiments, the effect of purified recombinant XTH proteins of Selaginella kraussiana on the extension of isolated onion epidermis was recorded. KEY RESULTS: Fluorescent xyloglucan endotransglucosylase (XET) assays demonstrate that exogeneous XTH can act on isolated onion epidermis cell walls. Furthermore, cell wall extension was significantly increased upon addition of XTH to the isolated epidermis, but only transverse to the net orientation of cellulose microfibrils. CONCLUSIONS: The results provide evidence that XTHs can act as cell wall-loosening enzymes.