Cutin:xyloglucan transacylase (CXT) activity covalently links cutin to a plant cell-wall polysaccharide
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Cutin:xyloglucan transacylase (CXT) activity covalently links cutin to a plant cell-wall polysaccharide. / Xin, Anzhou; Fry, Stephen C.
In: Journal of Plant Physiology, Vol. 262, 153446, 2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Cutin:xyloglucan transacylase (CXT) activity covalently links cutin to a plant cell-wall polysaccharide
AU - Xin, Anzhou
AU - Fry, Stephen C.
PY - 2021
Y1 - 2021
N2 - The shoot epidermal cell wall in land-plants is associated with a polyester, cutin, which controls water loss and possibly organ expansion. Covalent bonds between cutin and its neighbouring cell-wall polysaccharides have long been proposed. However, the lack of biochemical evidence makes cutin-polysaccharide linkages largely conjectural. Here we optimised a portfolio of radiochemical assays to look for cutin-polysaccharide ester bonds in the epidermis of pea epicotyls, ice-plant leaves and tomato fruits, based on the hypothesis that a transacylase remodels cutin in a similar fashion to cutin synthase and cutin:cutin transacylase activities. Through in-situ enzyme assays and chemical degradations coupled with chromatographic analysis of the 3H-labelled products, we observed that among several wall-related oligosaccharides tested, only a xyloglucan oligosaccharide ([3H] XXXGol) could acquire ester-bonds from endogenous cutin, suggesting a cutin:xyloglucan transacylase (CXT). CXT activity was heat-labile, time-dependent, and maximal at near-neutral pH values. In-situ CXT activity peaked in nearly fully expanded tomato fruits and ice-plant leaves. CXT activity positively correlated with organ growth rate, suggesting that it contributes to epidermal integrity during rapid expansion. This study uncovers hitherto unappreciated re-structuring processes in the plant epidermis and provides a step towards the identification of CXT and its engineering for biotechnological applications.
AB - The shoot epidermal cell wall in land-plants is associated with a polyester, cutin, which controls water loss and possibly organ expansion. Covalent bonds between cutin and its neighbouring cell-wall polysaccharides have long been proposed. However, the lack of biochemical evidence makes cutin-polysaccharide linkages largely conjectural. Here we optimised a portfolio of radiochemical assays to look for cutin-polysaccharide ester bonds in the epidermis of pea epicotyls, ice-plant leaves and tomato fruits, based on the hypothesis that a transacylase remodels cutin in a similar fashion to cutin synthase and cutin:cutin transacylase activities. Through in-situ enzyme assays and chemical degradations coupled with chromatographic analysis of the 3H-labelled products, we observed that among several wall-related oligosaccharides tested, only a xyloglucan oligosaccharide ([3H] XXXGol) could acquire ester-bonds from endogenous cutin, suggesting a cutin:xyloglucan transacylase (CXT). CXT activity was heat-labile, time-dependent, and maximal at near-neutral pH values. In-situ CXT activity peaked in nearly fully expanded tomato fruits and ice-plant leaves. CXT activity positively correlated with organ growth rate, suggesting that it contributes to epidermal integrity during rapid expansion. This study uncovers hitherto unappreciated re-structuring processes in the plant epidermis and provides a step towards the identification of CXT and its engineering for biotechnological applications.
KW - Epidermis remodelling
KW - Cutin
KW - Xyloglucan
KW - Ester bond
KW - Transacylase
KW - Cell expansion
KW - Polyester-polysaccharide conjugates
KW - LEAF CUTICLE
KW - BIOSYNTHESIS
KW - IDENTIFICATION
KW - DEGRADATION
KW - GLUCANASE
KW - BODYGUARD
KW - ENZYMES
KW - BONDS
KW - ACID
U2 - 10.1016/j.jplph.2021.153446
DO - 10.1016/j.jplph.2021.153446
M3 - Journal article
C2 - 34051591
VL - 262
JO - Journal of Plant Physiology
JF - Journal of Plant Physiology
SN - 0176-1617
M1 - 153446
ER -
ID: 273018938