Ten isoenzymes of xyloglucan endotransglycosylase from plant cell walls select and cleave the donor substrate stochastically

To map the preferred cleavage sites of xyloglucan endotransglycosylases (XETs; EC 2.4.1.207) along the donor substrate chain, we incubated the enzymes with tamarind (Tamarindus indica) xyloglucan (donor substrate; ≈ 205kDa; 21µM) plus the nonasaccharide [3H]XLLGol (Gal2·Xyl3·Glc3· [3H]glucitol; acceptor substrate; 0.6µM). After short incubation times, to minimize multiple cleavages, the size of the 3H-labelled transglycosylation products (determined by gel-permeation chromatography) indicated the positions of the cleavage sites relative to the non-reducing terminus of the donor. There was very little difference between the size profiles of the products formed by any of ten XETs tested [one native XET purified from cauliflower (Brassica oleracea) florets, four native XET isoenzymes purified from etiolated mung-bean (Phaseolus aureus) shoots, native XETs purified from lentil (Lens culinaris) and nasturtium (Tropaeolum majus) seeds, and three insect-cell-produced thale-cress (Arabidopsis thaliana) XETs (EXGT, TCH4 and MERI-5)]. All such product profiles showed a good fit to a model in which the enzyme chooses its donor substrate independently of size and attacks it, once only, at a randomly selected cleavage site. The results therefore do not support the hypothesis that different XET isoenzymes are adapted to produce longer or shorter products such as might favour either the efficient integration of new xyloglucan into the cell wall or the re-structuring of old xyloglucan within an expanding wall.

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Release of complexed xyloglucan endotransglycosylase (XET) from plant cell walls by a transglycosylation reaction with xyloglucan-derived oligosaccharides

Plant Physiology and Biochemistry ◽

10.1016/s0981-9428(01)01313-4 ◽

2001 ◽

Vol 39 (11) ◽

pp. 927-932 ◽

Cited By ~ 12

Author(s):

Zdena Sulová ◽

Richard Baran ◽

Vladimír Farkaš

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Plant Cell Walls ◽

Xyloglucan Endotransglycosylase ◽

Transglycosylation Reaction

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Exploration of cell wall architecture with the rapid-freeze deep-etch technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146485 ◽

1993 ◽

Vol 51 ◽

pp. 128-129

Author(s):

Béatrice Satiat-Jeunemaitre ◽

Chris Hawes

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Cell Biology ◽

Molecular Model ◽

Three Dimensional ◽

Secretory Activity ◽

Wall Structure ◽

Specimen Preparation ◽

Molecular Architecture ◽

Plant Cell Walls

The comprehension of the molecular architecture of plant cell walls is one of the best examples in cell biology which illustrates how developments in microscopy have extended the frontiers of a topic. Indeed from the first electron microscope observation of cell walls it has become apparent that our understanding of wall structure has advanced hand in hand with improvements in the technology of specimen preparation for electron microscopy. Cell walls are sub-cellular compartments outside the peripheral plasma membrane, the construction of which depends on a complex cellular biosynthetic and secretory activity (1). They are composed of interwoven polymers, synthesised independently, which together perform a number of varied functions. Biochemical studies have provided us with much data on the varied molecular composition of plant cell walls. However, the detailed intermolecular relationships and the three dimensional arrangement of the polymers in situ remains a mystery. The difficulty in establishing a general molecular model for plant cell walls is also complicated by the vast diversity in wall composition among plant species.

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Current challenges in plant cell walls

10.3389/978-2-88919-086-7 ◽

2013 ◽

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Plant Cell Walls

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Plant cell walls. Final progress report for the period August 1, 2000 - June 30, 2001

10.2172/804156 ◽

2000 ◽

Author(s):

Deborah Delmer

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Progress Report ◽

Plant Cell Walls

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Wheat cell walls and constituent polysaccharides induce similar microbiota profiles upon in vitro fermentation despite different short chain fatty acid end-product levels.

Food & Function ◽

10.1039/d0fo02509g ◽

2021 ◽

Author(s):

Shiyi Lu ◽

Deirdre Mikkelsen ◽

Hong Yao ◽

Barbara Williams ◽

Bernadine Flanagan ◽

...

Keyword(s):

Fatty Acid ◽

Gut Microbiota ◽

Plant Cell ◽

Cell Walls ◽

Short Chain Fatty Acid ◽

Chain Fatty Acid ◽

Plant Cell Walls ◽

Human Gut ◽

In Vitro Fermentation

Plant cell walls as well as their component polysaccharides in foods can be utilized to alter and maintain a beneficial human gut microbiota, but it is not known whether the...

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Plant Cell Wall Hydration and Plant Physiology: An Exploration of the Consequences of Direct Effects of Water Deficit on the Plant Cell Wall

Plants ◽

10.3390/plants10071263 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1263

Author(s):

David Stuart Thompson ◽

Azharul Islam

Keyword(s):

Cell Wall ◽

Water Content ◽

Bacterial Cellulose ◽

Plant Cell ◽

Cell Walls ◽

Plant Cell Wall ◽

Plant Cell Walls ◽

Cell Wall Polysaccharides ◽

Degree Of Hydration ◽

Cellulose Composites

The extensibility of synthetic polymers is routinely modulated by the addition of lower molecular weight spacing molecules known as plasticizers, and there is some evidence that water may have similar effects on plant cell walls. Furthermore, it appears that changes in wall hydration could affect wall behavior to a degree that seems likely to have physiological consequences at water potentials that many plants would experience under field conditions. Osmotica large enough to be excluded from plant cell walls and bacterial cellulose composites with other cell wall polysaccharides were used to alter their water content and to demonstrate that the relationship between water potential and degree of hydration of these materials is affected by their composition. Additionally, it was found that expansins facilitate rehydration of bacterial cellulose and cellulose composites and cause swelling of plant cell wall fragments in suspension and that these responses are also affected by polysaccharide composition. Given these observations, it seems probable that plant environmental responses include measures to regulate cell wall water content or mitigate the consequences of changes in wall hydration and that it may be possible to exploit such mechanisms to improve crop resilience.

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