Kinetics of Integration of Xyloglucan into the Walls of Suspension-Cultured Rose Cells

Edelmann, Hans G.; Fry, Stephen C.

doi:10.1093/jxb/43.4.463

Cited by 28 publications

(29 citation statements)

References 31 publications

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“…The experiment was a pulse-labelling in which the synthesis of [$H]xyloglucan was essentially restricted to a period 1-2 h after the feeding of [$H]arabinose [8,27]. Despite this, the density of the [$H]xyloglucan in the "$C-fed culture increased (significant positive gradient ; P 0.05) during the 7 days after the ["#C]glycerol ["$C]glucose shift (Figure 8b).…”

Section: Dual-labelling Experiments To Detect Interpolymeric Transglymentioning

confidence: 99%

“…In itro, the acceptor can be a high-M r xyloglucan or a short xyloglucan oligomer as small as a pentasaccharide [25]. Transglycosylation between xyloglucan chains in the cell wall could play a role in wall construction [8,26,27] and\or wall loosening [8,14,16,21,22,25,28]. Progress in testing these ideas has been hampered by our inability to say whether XET catalyses interpolymeric transglycosylation in i o. XETs are known to catalyse polymer-to-oligomer transglycosylation in itro [15][16][17]25], interpolymeric transglycosylation in itro [17,29,30] and polymer-to-oligomer transglycosylation in i o (although not necessarily involving wall-bound polymer) [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…They rapidly take up -[1-$H]arabinose and incorporate a substantial proportion of the radioactivity into [xylosyl-$H]xyloglucan [8,27]. This incorporation proceeds via the scavenger pathway :…”

Section: Introductionmentioning

confidence: 99%

“…Thus radioactivity from exogenous [$H]arabinose is incorporated into the -arabinose and -xylose residues of polysaccharides, whereas the hexose and uronic acid residues are not labelled [31,32]. Even without the use of a ' cold chase ', a single dose of [$H]arabinose is utilized rapidly enough to give labelling kinetics analogous to a pulse-chase experiment, in which the pulse (1-2 h) is 10 % of a cell cycle [8,27]. Most of the newly synthesized [$H]xyloglucan binds to the walls very soon after secretion [27].…”

Section: Introductionmentioning

confidence: 99%

“…Even without the use of a ' cold chase ', a single dose of [$H]arabinose is utilized rapidly enough to give labelling kinetics analogous to a pulse-chase experiment, in which the pulse (1-2 h) is 10 % of a cell cycle [8,27]. Most of the newly synthesized [$H]xyloglucan binds to the walls very soon after secretion [27]. Rosa cells synthesize xyloglucan as relatively short chains (M r 10 000) (J. E. Thompson and S. C. Fry, unpublished work), but upon integration into the wall the chains increase in M r to $ 200 000 [8], suggesting that xyloglucans covalently attach to one another during integration.…”

Section: Introductionmentioning

confidence: 99%

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Xyloglucan undergoes interpolymeric transglycosylation during binding to the plant cell wall in vivo: evidence from 13C/3H dual labelling and isopycnic centrifugation in caesium trifluoroacetate

Thompson

Smith

Fry

1997

Biochemical Journal

105

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Xyloglucan from the walls of Rosa cells that had been cultured on [12C]- or [13C]-glucose formed bands in caesium trifluoroacetate with mean buoyant densities of 1.575 or 1.616 g/ml respectively. Incubation of a mixture of [13C,3H]xyloglucan and [12C,1H]xyloglucan in the presence of xyloglucan endotransglycosylase (XET) activity caused the mean buoyant density of the radioactive material to decrease, indicating that interpolymeric transglycosylation could be detected in vitro. We used two 13C/3H-dual-labelling protocols to look for interpolymeric transglycosylation in vivo. In protocol A, [13C]glucose-grown Rosa cells were transferred into [12C]glucose medium 6 h after a ≈ 2 h pulse of L-[1-3H]arabinose (which radiolabels the xylose residues of xyloglucan). The mean buoyant density of the wall-bound [3H]xyloglucan decreased during the following 7 days in culture. This indicates that, during or after the wall-binding of newly synthesized [12C,1H]xyloglucan, it became covalently attached to previously wall-bound [13C,3H]xyloglucan. In protocol B, [12C]glycerol- or [12C]glucose-grown Rosa cells were transferred into [13C]glucose medium, 20 or 60 min before a ≈ 2 h pulse of [3H]arabinose. The buoyant density of the earliest wall-bound [3H]xyloglucan showed that it had a 12C/13C ratio of ~ 1:1. This indicates that, during (or, implausibly, before) wall-binding, the newly synthesized [13C,3H]xyloglucan became covalently attached to previously synthesized [12C]xyloglucan. During the following 7 days in culture, the mean buoyant density of the [3H]xyloglucan increased, showing that later-synthesized [13C,1H]xyloglucan can be covalently attached to previously wall-bound [12C,13C,3H]xyloglucan. The only known mechanism by which segments of xyloglucans could become covalently attached to each other in the cell wall is by interpolymeric transglycosylation catalysed by XET. We conclude that XET-catalysed interpolymeric transglycosylation accompanies, and probably causes, the integration of newly secreted xyloglucan into the cell-wall architecture.

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Section: Dual-labelling Experiments To Detect Interpolymeric Transglymentioning

confidence: 99%