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1.
Hoffman M Jia Z Peña MJ Cash M Harper A Blackburn AR Darvill A York WS 《Carbohydrate research》2005,340(11):1826-1840
The structures of xyloglucans from several plants in the subclass Asteridae were examined to determine how their structures vary in different taxonomic orders. Xyloglucans, solubilized from plant cell walls by a sequential (enzymatic and chemical) extraction procedure, were isolated, and their structures were characterized by NMR spectroscopy and mass spectrometry. All campanulids examined, including Lactuca sativa (lettuce, order Asterales), Tenacetum ptarmiciflorum (dusty miller, order Asterales), and Daucus carota (carrot, order Apiales), produce typical xyloglucans that have an XXXG-type branching pattern and contain alpha-d-Xylp-, beta-D-Galp-(1-->2)-alpha-D-Xylp-, and alpha-L-Fucp-(1-->2)-beta-D-Galp-(1-->2)-alpha-D-Xylp- side chains. However, the lamiids produce atypical xyloglucans. For example, previous analyses showed that Capsicum annum (pepper) and Lycopersicon esculentum (tomato), two species in the order Solanales, and Olea europaea (olive, order Lamiales) produce xyloglucans that contain arabinosyl and galactosyl residues, but lack fucosyl residues. The XXGG-type xyloglucans produced by Solanaceous species are less branched than the XXXG-type xyloglucan produced by Olea europaea. This study shows that Ipomoea pupurea (morning glory, order Solanales), Ocimum basilicum (basil, order Lamiales), and Plantago major (plantain, order Lamiales) all produce xyloglucans that lack fucosyl residues and have an unusual XXGGG-type branching pattern in which the basic repeating core contains five glucose subunits in the backbone. Furthermore, Neruim oleander (order Gentianales) produces an XXXG-type xyloglucan that contains arabinosyl, galactosyl, and fucosyl residues. The appearance of this intermediate xyloglucan structure in oleander has implications regarding the evolutionary development of xyloglucan structure and its role in primary plant cell walls. 相似文献
2.
Kulkarni AR Peña MJ Avci U Mazumder K Urbanowicz BR Pattathil S Yin Y O'Neill MA Roberts AW Hahn MG Xu Y Darvill AG York WS 《Glycobiology》2012,22(3):439-451
Glucuronoxylans with a backbone of 1,4-linked β-D-xylosyl residues are ubiquitous in the secondary walls of gymnosperms and angiosperms. Xylans have been reported to be present in hornwort cell walls, but their structures have not been determined. In contrast, the presence of xylans in the cell walls of mosses and liverworts remains a subject of debate. Here we present data that unequivocally establishes that the cell walls of leafy tissue and axillary hair cells of the moss Physcomitrella patens contain a glucuronoxylan that is structurally similar to glucuronoxylans in the secondary cell walls of vascular plants. Some of the 1,4-linked β-D-xylopyranosyl residues in the backbone of this glucuronoxylan bear an α-D-glucosyluronic acid (GlcpA) sidechain at O-2. In contrast, the lycopodiophyte Selaginella kraussiana synthesizes a glucuronoxylan substituted with 4-O-Me-α-D-GlcpA sidechains, as do many hardwood species. The monilophyte Equisetum hyemale produces a glucuronoxylan with both 4-O-Me-α-D-GlcpA and α-D-GlcpA sidechains, as does Arabidopsis. The seedless plant glucuronoxylans contain no discernible amounts of the reducing-end sequence that is characteristic of gymnosperm and eudicot xylans. Phylogenetic studies showed that the P. patens genome contains genes with high sequence similarity to Arabidopsis CAZy family GT8, GT43 and GT47 glycosyltransferases that are likely involved in xylan synthesis. We conclude that mosses synthesize glucuronoxylan that is structurally similar to the glucuronoxylans present in the secondary cell walls of lycopodiophytes, monilophytes, and many seed-bearing plants, and that several of the glycosyltransferases required for glucuronoxylan synthesis evolved before the evolution of tracheophytes. 相似文献
3.
In order to gain insight into the mechanism of cell extension growth, enzymic processes involved in structural modification of cell wall xyloglucans were investigated, using an apoplastic enzyme preparation from epicotyls of dark grown Vigna angularis Ohwi et Ohashi cv. Takara and purified xyloglucans derived from cell walls of Vigna. The reaction of Vigna xyloglucan (mass average molecular weight=420 kDa) with the apoplastic enzyme preparation gave three fractions: (1) a waterinsoluble high molecular weight (820 kDa) xyloglucan fraction (WI), (2) a watersoluble low molecular weight (149 kDa) xyloglucan fraction (WS), and (3) an 80% ethanol-soluble monosaccharide fraction (ES). WI and WS were chiefly composed of t -galactosyl-, t -xylosyl-, 2-xylosyl-, 4-glucosyl- and 4,6-glucosyl residues, whereas ES was composed of fucose, galactose, glucose and xylose monomers. The data indicate that WI is generated by the linking of xyloglucan molecules by some alkali stable linkages, probably of glycosidic nature. The optimal pH for the WI-producing activity of the apoplastic enzyme preparation was 5.4. Higher WI-producing activity was detected in the upper juvenile than in the lower non-elongating regions of the epicotyl. Our data suggest the possible involvement of a transglycosylation reaction in the structural changes of the xyloglucans that are responsible for cell extension growth of the Vigna angularis epicotyl. The data are also consistent with the idea that the enzymic processes are regulated by hydrogen ions in the apoplastic space. 相似文献
4.
Cell wall polysaccharides from fern leaves: evidence for a mannan-rich Type III cell wall in Adiantum raddianum 总被引:1,自引:0,他引:1
Silva GB Ionashiro M Carrara TB Crivellari AC Tiné MA Prado J Carpita NC Buckeridge MS 《Phytochemistry》2011,72(18):2352-2360
Primary cell walls from plants are composites of cellulose tethered by cross-linking glycans and embedded in a matrix of pectins. Cell wall composition varies between plant species, reflecting in some instances the evolutionary distance between them. In this work the monosaccharide compositions of isolated primary cell walls of nine fern species and one lycophyte were characterized and compared with those from Equisetum and an angiosperm dicot. The relatively high abundance of mannose in these plants suggests that mannans may constitute the major cross-linking glycan in the primary walls of pteridophytes and lycophytes. Pectin-related polysaccharides contained mostly rhamnose and uronic acids, indicating the presence of rhamnogalacturonan I highly substituted with galactose and arabinose. Structural and fine-structural analyses of the hemicellulose fraction of leaves of Adiantum raddianum confirmed this hypothesis. Linkage analysis showed that the mannan contains mostly 4-Man with very little 4,6-Man, indicating a low percentage of branching with galactose. Treatment of the mannan-rich fractions with endo-β-mannanase produced characteristic mannan oligosaccharides. Minor amounts of xyloglucan and xylans were also detected. These data and those of others suggest that all vascular plants contain xyloglucans, arabinoxylans, and (gluco)mannans, but in different proportions that define cell wall types. Whereas xyloglucan and pectin-rich walls define Type I walls of dicots and many monocots, arabinoxylans and lower proportion of pectin define the Type II walls of commelinoid monocots. The mannan-rich primary walls with low pectins of many ferns and a lycopod indicate a fundamentally different wall type among land plants, the Type III wall. 相似文献
5.
Cell-wall material from parenchymatous tissues of apple was sequentially extracted with 50mm NaOH at 1°, m KOH at 1° and 20°, and 4m KOH at 20°, to leave a residue of α-cellulose. From the 4m KOH-soluble fraction, a crude xyloglucan was isolated by anion-exchange chromatography, and further resolved into seven xyloglucans by borate anion-exchange chromatography. The relative amounts of the xyloglucans, in order of elution, were 2.7:1.3:29.7:1.0:3.2:1.2:10.3. The structural features of five of the xyloglucans were determined by methylation analysis. These results show that apple xyloglucans exhibit heterogeneity. 相似文献
6.
Markus Pauly Stefan Eberhard Peter Albersheim Alan Darvill William S. York 《Planta》2001,214(1):67-74
Mutation of the Arabidopsis thaliana (L.) Heynh. gene MUR1, which encodes an isoform of GDP-D-mannose-4,6-dehydratase, affects the biosynthetic conversion of GDP-mannose to GDP-fucose. Cell walls in the aerial tissues of mur1 plants are almost devoid of alpha-L-fucosyl residues, which are partially replaced by closely related alpha-L-galactosyl residues. A line of suspension-cultured A. thaliana cells was generated from leaves of mur1 plants and the structure of the xyloglucan in the walls of these cells was structurally characterized. Xyloglucan fractions were prepared from the walls of both wild-type (WT) and mur1 cells by sequential extraction with a xyloglucan-specific endoglucanase (XEG) and aqueous KOH. Structural analysis of these fractions revealed that xyloglucan produced by cultured mur1 cells is similar, but not identical to that isolated from leaves of mur1 plants. As previously reported for mur1 leaves, the xyloglucan from cultured mur1 cells contains less than 5% of the fucose present in the xyloglucan from WT cells. Fucosylation of the xyloglucan is substantially restored when mur1 cells are grown in medium supplemented with L-fucose. Xyloglucan isolated from leaves contains more oligosaccharide subunits in which the central sidechain is terminated with a beta-D-galactosyl residue than does xyloglucan prepared from cultured cells. This was observed for both mur1 and WT plants, indicating that this correlation is independent of the mur1 mutation and that it is possible to distinguish changes due to genetic mutation from those due to the physiological state of the cells in culture. Suspension-cultured cells thus provide a convenient source of genetically altered cell wall material, facilitating the biochemical characterization of mutations that affect cell wall structure. 相似文献
7.
《Phytochemistry》2012
Little is known about the structures of the xyloglucans in the primary cell walls of vascular plants (tracheophytes) other than angiosperms. Xyloglucan structures were examined in 13 species of gymnosperms, 13 species of monilophytes (ferns sensu lato), and two species of lycophytes. Wall preparations were obtained, extracted with 6 M sodium hydroxide, and the extracts treated with a xyloglucan-specific endo-(1 → 4)-β-glucanase preparation. The oligosaccharides released were analysed by matrix-assisted laser-desorption ionisation time-of-flight mass spectrometry and by high-performance anion-exchange chromatography. The xyloglucan oligosaccharide profiles from the gymnosperm walls were similar to those from the walls of most eudicotyledons and non-commelinid monocotyledons, indicating that the xyloglucans were fucogalactoxyloglucans, containing the fucosylated units XXFG and XLFG. The xyloglucan oligosaccharide profiles for six of the monilophyte species were similar to those of the gymnosperms, indicating they were also fucogalactoxyloglucans. Phylogenetically, these monilophyte species were from both basal and more derived orders. However, the profiles for the other monilophyte species showed various significant differences, including additional oligosaccharides. In three of the species, these additional oligosaccharides contained arabinosyl residues which were most abundant in the profile of Equisetum hyemale. The two species of lycophytes examined, Selaginella kraussiana and Lycopodium cernuum, had quite different xyloglucan oligosaccharide profiles, but neither were fucogalactoxyloglucans. The S. kraussiana profile had abundant oligosaccharides containing arabinosyl residues. The L. cernuum profile indicated the xyloglucan had a very complex structure. 相似文献
8.
Pauly M; Andersen LN; Kauppinen S; Kofod LV; York WS; Albersheim P; Darvill A 《Glycobiology》1999,9(1):93-100
A full-length c-DNA encoding a xyloglucan-specific endo -beta-1, 4-
glucanase (XEG) has been isolated from the filamentous fungus Aspergillus
aculeatus by expression cloning in yeast. The colonies expressing
functional XEG were identified on agar plates containing azurine-dyed
cross-linked xyloglucan. The cDNA encoding XEG was isolated, sequenced,
cloned into an Aspergillus expression vector, and transformed into
Aspergillus oryzae for heterologous expression. The recombinant enzyme was
purified to apparent homogeneity by anion- exchange and gel permeation
chromatography. The recombinant XEG has a molecular mass of 23,600, an
isoelectric point of 3.4, and is optimally stable at a pH of 3.4 and
temperature below 30 degreesC. The enzyme hydrolyzes structurally diverse
xyloglucans from various sources, but hydrolyzes no other cell wall
component and can therefore be considered a xyloglucan-specific endo
-beta-1, 4-glucanohydrolase. XEG hydrolyzes its substrates with retention
of the anomeric configuration. The Kmof the recombinant enzyme is 3.6
mg/ml, and its specific activity is 260 micromol/min per mg protein. The
enzyme was tested for its ability to solubilize xyloglucan oligosaccharides
from plant cell walls. It was shown that treatment of plant cell walls with
XEG yields only xyloglucan oligosaccharides, indicating that this enzyme
can be a powerful tool in the structural elucidation of xyloglucans.
相似文献
9.
Occurrence of the primary cell wall polysaccharide rhamnogalacturonan II in pteridophytes, lycophytes, and bryophytes. Implications for the evolution of vascular plants
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Matsunaga T Ishii T Matsumoto S Higuchi M Darvill A Albersheim P O'Neill MA 《Plant physiology》2004,134(1):339-351
Borate ester cross-linking of the cell wall pectic polysaccharide rhamnogalacturonan II (RG-II) is required for the growth and development of angiosperms and gymnosperms. Here, we report that the amounts of borate cross-linked RG-II present in the sporophyte primary walls of members of the most primitive extant vascular plant groups (Lycopsida, Filicopsida, Equisetopsida, and Psilopsida) are comparable with the amounts of RG-II in the primary walls of angiosperms. By contrast, the gametophyte generation of members of the avascular bryophytes (Bryopsida, Hepaticopsida, and Anthocerotopsida) have primary walls that contain small amounts (approximately 1% of the amounts of RG-II present in angiosperm walls) of an RG-II-like polysaccharide. The glycosyl sequence of RG-II is conserved in vascular plants, but these RG-IIs are not identical because the non-reducing L-rhamnosyl residue present on the aceric acid-containing side chain of RG-II of all previously studied plants is replaced by a 3-O-methyl rhamnosyl residue in the RG-IIs isolated from Lycopodium tristachyum, Ceratopteris thalictroides, Platycerium bifurcatum, and Psilotum nudum. Our data indicate that the amount of RG-II incorporated into the walls of plants increased during the evolution of vascular plants from their bryophyte-like ancestors. Thus, the acquisition of a boron-dependent growth habit may be correlated with the ability of vascular plants to maintain upright growth and to form lignified secondary walls. The conserved structures of pteridophyte, lycophyte, and angiosperm RG-IIs suggests that the genes and proteins responsible for the biosynthesis of this polysaccharide appeared early in land plant evolution and that RG-II has a fundamental role in wall structure. 相似文献
10.
Elongation growth of dark-grown azuki bean (Vigna angularis Ohwi et Ohashi cv. Takara) epicotyls was suppressed by hypergravity at 30 x g and above. Acceleration at 300 x g significantly decreased the mechanical extensibility of cell walls. The amounts of cell wall polysaccharides (pectin, hemicellulose-II and cellulose) per unit length of epicotyls increased under the hypergravity condition. Hypergravity also increased the amounts and the weight-average molecular mass of xyloglucans in the hemicellulose-II fraction, while decreasing the activity of xyloglucan-degrading enzymes extracted from epicotyl cell walls. These results suggest that hypergravity increases the amounts and the molecular mass of xyloglucans by decreasing xyloglucan-degrading activity. Modification of xyloglucan metabolism as well as the thickening of cell walls under hypergravity conditions seems to be involved in making the cell wall mechanically rigid, thereby inhibiting elongation growth of azuki bean epicotyls. 相似文献
11.
Whitney SE Wilson E Webster J Bacic A Reid JS Gidley MJ 《American journal of botany》2006,93(10):1402-1414
A cellulose/xyloglucan framework is considered to form the basis for the mechanical properties of primary plant cell walls and hence to have a major influence on the biomechanical properties of growing, fleshy plant tissues. In this study, structural variants of xyloglucan have been investigated as components of composites with bacterial cellulose as a simplified model for the cellulose/xyloglucan framework of primary plant cell walls. Evidence for molecular binding to cellulose with perturbation of cellulose crystallinity was found for all xyloglucan types. High molecular mass samples gave homogeneous centimeter-scale composites with extensive cross-linking of cellulose with xyloglucan. Lower molecular mass xyloglucans gave heterogeneous composites having a range of microscopic structures with little, if any, cross-linking. Xyloglucans with reduced levels of galactose substitution had evidence of self-association, competitive with cellulose binding. At comparable molecular mass, fucose substitution resulted in a modest promotion of microscopic features characteristic of primary cell walls. Taken together, the data are evidence that galactose substitution of the xyloglucan core structure is a major determinant of cellulose composite formation and properties, with additional fucose substitution acting as a secondary modulator. These conclusions are consistent with reported structural and mechanical properties of Arabidopsis mutants lacking specific fucose and/or galactose residues. 相似文献
12.
Different xyloglucan (XG) fractions were isolated from Rubus fruticosus cells cultured in suspension. Sequential extraction showed that two distinct xyloglucans existed in the primary walls. The first could be easily extracted in alkali and the second was tightly associated to cellulose. A third fraction was isolated from the extracellular polysaccharides of the culture medium. The alkali-soluble XG and the extracellular XG showed many structural features in common. By use of an anti-XG polyclonal antibody, electron microscopy examination suggests that the extracellular hemicellulose is progressively released from the wall by a sloughing mechanism. Oligosaccharides prepared from the extracellular XG were purified and their structure examined by FAB-ms technique. When the nonasaccharide was added at low concentrations (10(-5) mg/ml) to the culture medium it was able to elicit several different glycanohydrolase activities associated to the cell wall. 相似文献
13.
Microsomal membrane preparations from growing regions of etiolated pea stems catalyzed the transfer of [14C]fucosyl units from GDP-[U-14C]-L-fucose into exogenously added xyloglucan acceptors, as well as into endogenous xyloglucan. The transfer was more effective using nonfucosylated tamarind seed xyloglucan than with pea wall xyloglucan in which almost all galactose units are already fucosylated. Hydrolysis of products by endo-1,4-beta-D-glucanase yielded in each case radioactive nonasaccharide as the main fucosylated product. UDP-galactose enhanced the fucosylation of endogenous primer but it had little effect on fucosyl transfer to exogenously added xyloglucans. Low-molecular-weight nonfucosylated oligosaccharide fragments up to the octasaccharide Glc4Xyl3Gal (obtained by endoglucanase action on tamarind seed xyloglucan) were ineffectual as fucosyl acceptors but inhibited the fucosylation of endogenous as well as of added xyloglucan. With octasaccharide, the inhibition was competitive in relation to the xyloglucan acceptor (Ki = 70 microM) and noncompetitive in relation to the donor GDP-fucose (Ki = 210 microM). It is concluded that fucosyltransferase acts independently and in a noncoordinated manner from other glycosyltransferases that are required to synthesize xyloglucan. Its active site recognizes a fragment longer than the galactosylated octasaccharide unit before transfucosylation will ensue. 相似文献
14.
15.
The main load-bearing network in the primary cell wall of most land plants is commonly depicted as a scaffold of cellulose microfibrils tethered by xyloglucans. However, a xyloglucan-deficient mutant (xylosyltransferase1/xylosyltransferase2 [xxt1/xxt2]) was recently developed that was smaller than the wild type but otherwise nearly normal in its development, casting doubt on xyloglucan's role in wall structure. To assess xyloglucan function in the Arabidopsis (Arabidopsis thaliana) wall, we compared the behavior of petiole cell walls from xxt1/xxt2 and wild-type plants using creep, stress relaxation, and stress/strain assays, in combination with reagents that cut or solubilize specific components of the wall matrix. Stress/strain assays showed xxt1/xxt2 walls to be more extensible than wild-type walls (supporting a reinforcing role for xyloglucan) but less extensible in creep and stress relaxation processes mediated by α-expansin. Fusicoccin-induced "acid growth" was likewise reduced in xxt1/xxt2 petioles. The results show that xyloglucan is important for wall loosening by α-expansin, and the smaller size of the xxt1/xxt2 mutant may stem from the reduced effectiveness of α-expansins in the absence of xyloglucan. Loosening agents that act on xylans and pectins elicited greater extension in creep assays of xxt1/xxt2 cell walls compared with wild-type walls, consistent with a larger mechanical role for these matrix polymers in the absence of xyloglucan. Our results illustrate the need for multiple biomechanical assays to evaluate wall properties and indicate that the common depiction of a cellulose-xyloglucan network as the major load-bearing structure is in need of revision. 相似文献
16.
Conformational analysis of xyloglucans 总被引:2,自引:0,他引:2
Xyloglucan isolated from the elongating regions of pea stems was examined using X-ray diffraction and energy calculations. The X-ray fibre pattern suggested that the backbone (1----4)-beta-D-glucan takes an extended two-fold helix similar to common cellulose. In order to study side chains (xylosyl or fucosyl-galactosyl-xylosyl residues) of the polysaccharide, energetically preferable conformations were searched by calculation of interactions between non-bonded atom pairs. A stepwise calculation for the conformation of fucosyl-galactosyl-xylosyl residue gave 10 allowed area (phi-psi) maps which are useful to deduce xyloglucan conformations of both monocotyledons and dicotyledons in the walls of growing plant cells. 相似文献
17.
18.
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. 相似文献
19.
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. 相似文献
20.
Xyloglucans isolated from cell walls of etiolated Glycine maxand Vigna sesquipedalis hypocotyls were subjected to fragmentationanalysis with cellulase for structural comparison with thosederived from Phaseolus aureus hypocotyls. The xyloglucans fromG. max and V. sesquipedalis had glucose, xylose, galactose andfucose in the approximate molar ratio of 10:6:4:1 and 10:7:3:1,respectively. However, the results of cellulase fragmentationanalysis of xyloglucans from the three species suggested thatthe basic structure of the xyloglucans in the cell walls ofthese bean-hypocotyls is almost the same; the structure is basedon two repeating oligosaccharide units, one of which consistsof glucose and xylose and the other of glucose, xylose, galactoseand fucose.
1 Present address: Toppan Printing Co., Ltd., Okaji, Sendai980, Japan. (Received February 3, 1977; ) 相似文献