The Experts below are selected from a list of 1269 Experts worldwide ranked by ideXlab platform
Takayuki Hoson - One of the best experts on this subject based on the ideXlab platform.
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Fucosylated high molecular mass but not non-fucosylated low molecular mass Xyloglucans undergo an extensive depolymerization in cell walls of azuki bean epicotyls
Journal of Plant Physiology, 2010Co-Authors: Kuninori Arai, Kazuyuki Wakabayashi, Kouichi Soga, Takayuki HosonAbstract:Abstract Epicotyl cuttings of azuki bean were incubated with [ 14 C]-glucose (Glc) or [ 3 H]-fucose (Fuc), and the metabolism of radiolabeled polymers in the 24% KOH-extractable cell wall fraction was investigated. Applied 14 C-Glc and 3 H-Fuc were predominantly incorporated into the glucan backbone and Fuc residue of xyloglucan molecules, respectively. On gel permeation chromatography, 14 C-polymers consisted of a main peak (0.7–1.0 MDa) and shoulder peak (30 kDa). The pattern was similar to that of iodine-reactive Xyloglucans in the fraction. On the other hand, 3 H-polymers consisted of a single peak eluted around 0.7–1.0 MDa. The elution patterns of 14 C- and 3 H-polymers were constant during the incubation period, although incorporated radioactivity increased with time. In the pulse-chase experiment, the high molecular mass peaks (0.7–1.0 MDa) of both 14 C- and 3 H-polymers showed an extensive molecular mass downshift, but not the shoulder peak of 14 C-polymers. These results indicate that Xyloglucans in the fraction consist of two types of molecules; fucosylated high molecular mass polymers and non-fucosylated low molecular mass polymers. Azuki bean epicotyls may synthesize both types of Xyloglucans independently, but only fucosylated Xyloglucans undergo an active depolymerization in the cell wall.
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Role of xyloglucan in gravitropic bending of azuki bean epicotyl.
Physiologia Plantarum, 2008Co-Authors: Toshimitsu Ikushima, Kouichi Soga, Takayuki Hoson, Teruo ShimmenAbstract:The mechanism of the gravitropic bending was studied in azuki bean epicotyls. The cell wall extensibility of the lower side became higher than that of the upper side in the epicotyl bending upward. The contents of matrix polysaccharides of the cell wall (pectin and xyloglucan in hemicellulose-II) in the lower side became smaller than those in the upper side. The molecular mass of Xyloglucans in the lower side decreased. After an epicotyl was fixed to a metal rod to prevent the bending, gravistimulation was applied. Fundamentally the same results were obtained with respect to rheological and chemical characteristics of the cell wall as those of epicotyls showing gravitropic bending. The present results suggested that the initial gravitropic bending was caused by the increase in extensibility of the lower side and the decrease in extensibility of the upper side via the change of the cell wall matrix, especially Xyloglucans.
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xyloglucan oligosaccharides cause cell wall loosening by enhancing xyloglucan endotransglucosylase hydrolase activity in azuki bean epicotyls
Plant and Cell Physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;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.
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stimulation of elongation growth and xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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action of xyloglucan hydrolase within the native cell wall architecture and its effect on cell wall extensibility in azuki bean epicotyls
Plant and Cell Physiology, 2002Co-Authors: Tomomi Kaku, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:Xyloglucan hydrolase (XGH) has recently been purified from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls as a new type of xyloglucan-degrading enzyme [Tabuchi et al. (2001) Plant Cell Physiol. 42: 154]. In the present study, the effects of XGH on the mechanical properties of the cell wall and on the level and the molecular size of Xyloglucans within the native wall architecture were examined in azuki bean epicotyls. When the epidermal tissue strips from the growing regions of azuki bean epicotyls were incubated with XGH, the mechanical extensibility of the cell wall dramatically increased. XGH exogenously applied to cell wall materials (homogenates) or epidermal tissue strips decreased the amount of Xyloglucans via the solubilization of the polysaccharides. Also, XGH substantially decreased the molecular mass of Xyloglucans in both materials. These results indicate that XGH is capable of hydrolyzing Xyloglucans within the native cell wall architecture and thereby increasing the cell wall extensibility in azuki bean epicotyls.
Seiichiro Kamisaka - One of the best experts on this subject based on the ideXlab platform.
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stimulation of elongation growth and xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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action of xyloglucan hydrolase within the native cell wall architecture and its effect on cell wall extensibility in azuki bean epicotyls
Plant and Cell Physiology, 2002Co-Authors: Tomomi Kaku, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:Xyloglucan hydrolase (XGH) has recently been purified from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls as a new type of xyloglucan-degrading enzyme [Tabuchi et al. (2001) Plant Cell Physiol. 42: 154]. In the present study, the effects of XGH on the mechanical properties of the cell wall and on the level and the molecular size of Xyloglucans within the native wall architecture were examined in azuki bean epicotyls. When the epidermal tissue strips from the growing regions of azuki bean epicotyls were incubated with XGH, the mechanical extensibility of the cell wall dramatically increased. XGH exogenously applied to cell wall materials (homogenates) or epidermal tissue strips decreased the amount of Xyloglucans via the solubilization of the polysaccharides. Also, XGH substantially decreased the molecular mass of Xyloglucans in both materials. These results indicate that XGH is capable of hydrolyzing Xyloglucans within the native cell wall architecture and thereby increasing the cell wall extensibility in azuki bean epicotyls.
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a new type of endo xyloglucan transferase devoted to xyloglucan hydrolysis in the cell wall of azuki bean epicotyls
Plant and Cell Physiology, 2001Co-Authors: Akira Tabuchi, Seiichiro Kamisaka, Hitoshi Mori, Takayuki HosonAbstract:;A new type of xyloglucan-degrading enzyme was isolated from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi cv. Takara) epicotyls and its characteristics were determined. The enzyme was purified to apparent homogeneity by Concanavalin A (Con A)-Sepharose, cation exchange, and gel filtration columns from a cell wall protein fraction extracted with 1 M sodium chloride. The purified enzyme gave a single protein band of 33 kDa on SDS-PAGE. The enzyme specifically cleaved Xyloglucans and showed maximum activity at pH 5.0 when assayed by the iodine-staining method. An increase in reducing power in xyloglucan solution was clearly detected after treatment with the purified enzyme. Xyloglucans with molecular masses of 500 and 25 kDa were gradually hydrolyzed to 5 kDa for 96 h without production of any oligo- or monosaccharide with the purified enzyme. The purified enzyme did not show an endo-type transglycosylation reaction, even in the presence of xyloglucan oligosaccharides. Partial amino acid sequences of the enzyme shared an identity with endo-xyloglucan transferase (EXGT) family, especially with xyloglucan endotransglycosylase (XET) from nasturtium. These results suggest that the enzyme is a new member of EXGT devoted solely to xyloglucan hydrolysis.
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gravitational force regulates elongation growth of arabidopsis hypocotyls by modifying xyloglucan metabolism
Advances in Space Research, 2001Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract:Abstract Growth of dark-grown Arabidopsis hypocotyls was suppressed under hypergravity conditions (300 g ), or was stimulated under microgravity conditions in space (Space Shuttle STS-95). The mechanical extensibility of cell walls decreased and increased under hypergravity and microgravity conditions, respectively. The amounts of cell wall polysaccharides (pectin, hemicellulose-I, hemicellulose-II and cellulose) per unit length of hypocotyls increased under hypergravity conditions, and decreased under microgravity conditions. The amount and the molecular mass of Xyloglucans also increased under the hypergravity conditions, while those decreased under microgravity conditions. The activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls decreased and increased under hypergravity and microgravity conditions, respectively. These results indicate that the amount and the molecular mass of Xyloglucans are affected by the magnitude of gravity and that such changes are caused by changes in xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell walls by gravity stimulus may be the primary event determining the cell wall extensibility, thereby regulating the growth rate of Arabidopsis hypocotyls.
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Hypergravity Increases the Molecular Mass of Xyloglucans by Decreasing Xyloglucan-Degrading Activity in Azuki Bean Epicotyls
Plant and Cell Physiology, 1999Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract: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.
Harry Brumer - One of the best experts on this subject based on the ideXlab platform.
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adaptation of syntenic xyloglucan utilization loci of human gut bacteroidetes to polysaccharide side chain diversity
Applied and Environmental Microbiology, 2019Co-Authors: Guillaume Dejean, Alexandra S Tauzin, Stuart W Bennett, Louise A Creagh, Harry BrumerAbstract:ABSTRACT Genome sequencing has revealed substantial variation in the predicted abilities of individual species within animal gut microbiota to metabolize the complex carbohydrates comprising dietary fiber. At the same time, a currently limited body of functional studies precludes a richer understanding of how dietary glycan structures affect the gut microbiota composition and community dynamics. Here, using biochemical and biophysical techniques, we identified and characterized differences among recombinant proteins from syntenic xyloglucan utilization loci (XyGUL) of three Bacteroides and one Dysgonomonas species from the human gut, which drive substrate specificity and access to distinct polysaccharide side chains. Enzymology of four syntenic glycoside hydrolase family 5 subfamily 4 (GH5_4) endo-xyloglucanases revealed surprising differences in xyloglucan (XyG) backbone cleavage specificity, including the ability of some homologs to hydrolyze congested branched positions. Further, differences in the complement of GH43 alpha-l-arabinofuranosidases and GH95 alpha-l-fucosidases among syntenic XyGUL confer distinct abilities to fully saccharify plant species-specific arabinogalactoxyloglucan and/or fucogalactoxyloglucan. Finally, characterization of highly sequence-divergent cell surface glycan-binding proteins (SGBPs) across syntenic XyGUL revealed a novel group of XyG oligosaccharide-specific SGBPs encoded within select Bacteroides. IMPORTANCE The catabolism of complex carbohydrates that otherwise escape the endogenous digestive enzymes of humans and other animals drives the composition and function of the gut microbiota. Thus, detailed molecular characterization of dietary glycan utilization systems is essential both to understand the ecology of these complex communities and to manipulate their compositions, e.g., to benefit human health. Our research reveals new insight into how ubiquitous members of the human gut microbiota have evolved a set of microheterogeneous gene clusters to efficiently respond to the structural variations of plant Xyloglucans. The data here will enable refined functional prediction of xyloglucan utilization among diverse environmental taxa in animal guts and beyond.
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structural dissection of a complex bacteroides ovatus gene locus conferring xyloglucan metabolism in the human gut
Open Biology, 2016Co-Authors: Glyn R Hemsworth, Andrew J Thompson, Judith Stepper, łukasz F Sobala, Travis Coyle, Johan Larsbrink, Oliver Spadiut, Ethan D Goddardborger, Keith A Stubbs, Harry BrumerAbstract:The human gastrointestinal tract harbours myriad bacterial species, collectively termed the microbiota, that strongly influence human health. Symbiotic members of our microbiota play a pivotal role in the digestion of complex carbohydrates that are otherwise recalcitrant to assimilation. Indeed, the intrinsic human polysaccharide-degrading enzyme repertoire is limited to various starch-based substrates; more complex polysaccharides demand microbial degradation. Select Bacteroidetes are responsible for the degradation of the ubiquitous vegetable Xyloglucans (XyGs), through the concerted action of cohorts of enzymes and glycan-binding proteins encoded by specific xyloglucan utilization loci (XyGULs). Extending recent (meta)genomic, transcriptomic and biochemical analyses, significant questions remain regarding the structural biology of the molecular machinery required for XyG saccharification. Here, we reveal the three-dimensional structures of an α-xylosidase, a β-glucosidase, and two α-l-arabinofuranosidases from the Bacteroides ovatus XyGUL. Aided by bespoke ligand synthesis, our analyses highlight key adaptations in these enzymes that confer individual specificity for xyloglucan side chains and dictate concerted, stepwise disassembly of xyloglucan oligosaccharides. In harness with our recent structural characterization of the vanguard endo-Xyloglucanse and cell-surface glycan-binding proteins, the present analysis provides a near-complete structural view of xyloglucan recognition and catalysis by XyGUL proteins.
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molecular dissection of xyloglucan recognition in a prominent human gut symbiont
Mbio, 2016Co-Authors: Alexandra S Tauzin, Harry Brumer, Louise A Creagh, Kurt J. Kwiatkowski, Nicole I. Orlovsky, Christopher J. Smith, Charles A. Haynes, Zdzislaw Wawrzak, Nicole M. KoropatkinAbstract:ABSTRACT Polysaccharide utilization loci (PUL) within the genomes of resident human gut Bacteroidetes are central to the metabolism of the otherwise indigestible complex carbohydrates known as “dietary fiber.” However, functional characterization of PUL lags significantly behind sequencing efforts, which limits physiological understanding of the human-bacterial symbiosis. In particular, the molecular basis of complex polysaccharide recognition, an essential prerequisite to hydrolysis by cell surface glycosidases and subsequent metabolism, is generally poorly understood. Here, we present the biochemical, structural, and reverse genetic characterization of two unique cell surface glycan-binding proteins (SGBPs) encoded by a xyloglucan utilization locus (XyGUL) from Bacteroides ovatus, which are integral to growth on this key dietary vegetable polysaccharide. Biochemical analysis reveals that these outer membrane-anchored proteins are in fact exquisitely specific for the highly branched xyloglucan (XyG) polysaccharide. The crystal structure of SGBP-A, a SusD homolog, with a bound XyG tetradecasaccharide reveals an extended carbohydrate-binding platform that primarily relies on recognition of the β-glucan backbone. The unique, tetra-modular structure of SGBP-B is comprised of tandem Ig-like folds, with XyG binding mediated at the distal C-terminal domain. Despite displaying similar affinities for XyG, reverse-genetic analysis reveals that SGBP-B is only required for the efficient capture of smaller oligosaccharides, whereas the presence of SGBP-A is more critical than its carbohydrate-binding ability for growth on XyG. Together, these data demonstrate that SGBP-A and SGBP-B play complementary, specialized roles in carbohydrate capture by B. ovatus and elaborate a model of how vegetable Xyloglucans are accessed by the Bacteroidetes . IMPORTANCE The Bacteroidetes are dominant bacteria in the human gut that are responsible for the digestion of the complex polysaccharides that constitute “dietary fiber.” Although this symbiotic relationship has been appreciated for decades, little is currently known about how Bacteroidetes seek out and bind plant cell wall polysaccharides as a necessary first step in their metabolism. Here, we provide the first biochemical, crystallographic, and genetic insight into how two surface glycan-binding proteins from the complex Bacteroides ovatus xyloglucan utilization locus (XyGUL) enable recognition and uptake of this ubiquitous vegetable polysaccharide. Our combined analysis illuminates new fundamental aspects of complex polysaccharide recognition, cleavage, and import at the Bacteroidetes cell surface that may facilitate the development of prebiotics to target this phylum of gut bacteria.
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Molecular Dissection of Xyloglucan Recognition in a Prominent Human Gut Symbiont
American Society for Microbiology, 2016Co-Authors: Alexandra S Tauzin, Harry Brumer, Louise A Creagh, Kurt J. Kwiatkowski, Nicole I. Orlovsky, Christopher J. Smith, Charles A. Haynes, Zdzislaw Wawrzak, Nicole M. KoropatkinAbstract:Polysaccharide utilization loci (PUL) within the genomes of resident human gut Bacteroidetes are central to the metabolism of the otherwise indigestible complex carbohydrates known as “dietary fiber.” However, functional characterization of PUL lags significantly behind sequencing efforts, which limits physiological understanding of the human-bacterial symbiosis. In particular, the molecular basis of complex polysaccharide recognition, an essential prerequisite to hydrolysis by cell surface glycosidases and subsequent metabolism, is generally poorly understood. Here, we present the biochemical, structural, and reverse genetic characterization of two unique cell surface glycan-binding proteins (SGBPs) encoded by a xyloglucan utilization locus (XyGUL) from Bacteroides ovatus, which are integral to growth on this key dietary vegetable polysaccharide. Biochemical analysis reveals that these outer membrane-anchored proteins are in fact exquisitely specific for the highly branched xyloglucan (XyG) polysaccharide. The crystal structure of SGBP-A, a SusD homolog, with a bound XyG tetradecasaccharide reveals an extended carbohydrate-binding platform that primarily relies on recognition of the β-glucan backbone. The unique, tetra-modular structure of SGBP-B is comprised of tandem Ig-like folds, with XyG binding mediated at the distal C-terminal domain. Despite displaying similar affinities for XyG, reverse-genetic analysis reveals that SGBP-B is only required for the efficient capture of smaller oligosaccharides, whereas the presence of SGBP-A is more critical than its carbohydrate-binding ability for growth on XyG. Together, these data demonstrate that SGBP-A and SGBP-B play complementary, specialized roles in carbohydrate capture by B. ovatus and elaborate a model of how vegetable Xyloglucans are accessed by the Bacteroidetes
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Molecular Dissection of Xyloglucan Recognition in a Prominent Human Gut Symbiont
mBio, 2016Co-Authors: Alexandra Tauzin, Harry Brumer, Kurt J. Kwiatkowski, Nicole I. Orlovsky, Christopher J. Smith, Charles A. Haynes, Zdzislaw Wawrzak, A. Louise Creagh, Nicole M. KoropatkinAbstract:Polysaccharide utilization loci (PUL) within the genomes of resident human gut Bacteroidetes are central to the metabolism of the otherwise indigestible complex carbohydrates known as "dietary fiber." However, functional characterization of PUL lags significantly behind sequencing efforts, which limits physiological understanding of the human-bacterial symbiosis. In particular, the molecular basis of complex polysaccharide recognition, an essential prerequisite to hydrolysis by cell surface glycosidases and subsequent metabolism, is generally poorly understood. Here, we present the biochemical, structural, and reverse genetic characterization of two unique cell surface glycan-binding proteins (SGBPs) encoded by a xyloglucan utilization locus (XyGUL) from Bacteroides ovatus, which are integral to growth on this key dietary vegetable polysaccharide. Biochemical analysis reveals that these outer membrane-anchored proteins are in fact exquisitely specific for the highly branched xyloglucan (XyG) polysaccharide. The crystal structure of SGBP-A, a SusD homolog, with a bound XyG tetradecasaccharide reveals an extended carbohydrate-binding platform that primarily relies on recognition of the beta-glucan backbone. The unique, tetra-modular structure of SGBP-B is comprised of tandem Ig-like folds, with XyG binding mediated at the distal C-terminal domain. Despite displaying similar affinities for XyG, reverse-genetic analysis reveals that SGBP-B is only required for the efficient capture of smaller oligosaccharides, whereas the presence of SGBP-A is more critical than its carbohydrate-binding ability for growth on XyG. Together, these data demonstrate that SGBP-A and SGBP-B play complementary, specialized roles in carbohydrate capture by B. ovatus and elaborate a model of how vegetable Xyloglucans are accessed by the Bacteroidetes. IMPORTANCE The Bacteroidetes are dominant bacteria in the human gut that are responsible for the digestion of the complex polysaccharides that constitute "dietary fiber." Although this symbiotic relationship has been appreciated for decades, little is currently known about how Bacteroidetes seek out and bind plant cell wall polysaccharides as a necessary first step in their metabolism. Here, we provide the first biochemical, crystallographic, and genetic insight into how two surface glycan-binding proteins from the complex Bacteroides ovatus xyloglucan utilization locus (XyGUL) enable recognition and uptake of this ubiquitous vegetable polysaccharide. Our combined analysis illuminates new fundamental aspects of complex polysaccharide recognition, cleavage, and import at the Bacteroidetes cell surface that may facilitate the development of prebiotics to target this phylum of gut bacteria.
Kazuyuki Wakabayashi - One of the best experts on this subject based on the ideXlab platform.
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Fucosylated high molecular mass but not non-fucosylated low molecular mass Xyloglucans undergo an extensive depolymerization in cell walls of azuki bean epicotyls
Journal of Plant Physiology, 2010Co-Authors: Kuninori Arai, Kazuyuki Wakabayashi, Kouichi Soga, Takayuki HosonAbstract:Abstract Epicotyl cuttings of azuki bean were incubated with [ 14 C]-glucose (Glc) or [ 3 H]-fucose (Fuc), and the metabolism of radiolabeled polymers in the 24% KOH-extractable cell wall fraction was investigated. Applied 14 C-Glc and 3 H-Fuc were predominantly incorporated into the glucan backbone and Fuc residue of xyloglucan molecules, respectively. On gel permeation chromatography, 14 C-polymers consisted of a main peak (0.7–1.0 MDa) and shoulder peak (30 kDa). The pattern was similar to that of iodine-reactive Xyloglucans in the fraction. On the other hand, 3 H-polymers consisted of a single peak eluted around 0.7–1.0 MDa. The elution patterns of 14 C- and 3 H-polymers were constant during the incubation period, although incorporated radioactivity increased with time. In the pulse-chase experiment, the high molecular mass peaks (0.7–1.0 MDa) of both 14 C- and 3 H-polymers showed an extensive molecular mass downshift, but not the shoulder peak of 14 C-polymers. These results indicate that Xyloglucans in the fraction consist of two types of molecules; fucosylated high molecular mass polymers and non-fucosylated low molecular mass polymers. Azuki bean epicotyls may synthesize both types of Xyloglucans independently, but only fucosylated Xyloglucans undergo an active depolymerization in the cell wall.
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xyloglucan oligosaccharides cause cell wall loosening by enhancing xyloglucan endotransglucosylase hydrolase activity in azuki bean epicotyls
Plant and Cell Physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;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.
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stimulation of elongation growth and xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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action of xyloglucan hydrolase within the native cell wall architecture and its effect on cell wall extensibility in azuki bean epicotyls
Plant and Cell Physiology, 2002Co-Authors: Tomomi Kaku, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:Xyloglucan hydrolase (XGH) has recently been purified from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls as a new type of xyloglucan-degrading enzyme [Tabuchi et al. (2001) Plant Cell Physiol. 42: 154]. In the present study, the effects of XGH on the mechanical properties of the cell wall and on the level and the molecular size of Xyloglucans within the native wall architecture were examined in azuki bean epicotyls. When the epidermal tissue strips from the growing regions of azuki bean epicotyls were incubated with XGH, the mechanical extensibility of the cell wall dramatically increased. XGH exogenously applied to cell wall materials (homogenates) or epidermal tissue strips decreased the amount of Xyloglucans via the solubilization of the polysaccharides. Also, XGH substantially decreased the molecular mass of Xyloglucans in both materials. These results indicate that XGH is capable of hydrolyzing Xyloglucans within the native cell wall architecture and thereby increasing the cell wall extensibility in azuki bean epicotyls.
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gravitational force regulates elongation growth of arabidopsis hypocotyls by modifying xyloglucan metabolism
Advances in Space Research, 2001Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract:Abstract Growth of dark-grown Arabidopsis hypocotyls was suppressed under hypergravity conditions (300 g ), or was stimulated under microgravity conditions in space (Space Shuttle STS-95). The mechanical extensibility of cell walls decreased and increased under hypergravity and microgravity conditions, respectively. The amounts of cell wall polysaccharides (pectin, hemicellulose-I, hemicellulose-II and cellulose) per unit length of hypocotyls increased under hypergravity conditions, and decreased under microgravity conditions. The amount and the molecular mass of Xyloglucans also increased under the hypergravity conditions, while those decreased under microgravity conditions. The activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls decreased and increased under hypergravity and microgravity conditions, respectively. These results indicate that the amount and the molecular mass of Xyloglucans are affected by the magnitude of gravity and that such changes are caused by changes in xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell walls by gravity stimulus may be the primary event determining the cell wall extensibility, thereby regulating the growth rate of Arabidopsis hypocotyls.
Kouichi Soga - One of the best experts on this subject based on the ideXlab platform.
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Fucosylated high molecular mass but not non-fucosylated low molecular mass Xyloglucans undergo an extensive depolymerization in cell walls of azuki bean epicotyls
Journal of Plant Physiology, 2010Co-Authors: Kuninori Arai, Kazuyuki Wakabayashi, Kouichi Soga, Takayuki HosonAbstract:Abstract Epicotyl cuttings of azuki bean were incubated with [ 14 C]-glucose (Glc) or [ 3 H]-fucose (Fuc), and the metabolism of radiolabeled polymers in the 24% KOH-extractable cell wall fraction was investigated. Applied 14 C-Glc and 3 H-Fuc were predominantly incorporated into the glucan backbone and Fuc residue of xyloglucan molecules, respectively. On gel permeation chromatography, 14 C-polymers consisted of a main peak (0.7–1.0 MDa) and shoulder peak (30 kDa). The pattern was similar to that of iodine-reactive Xyloglucans in the fraction. On the other hand, 3 H-polymers consisted of a single peak eluted around 0.7–1.0 MDa. The elution patterns of 14 C- and 3 H-polymers were constant during the incubation period, although incorporated radioactivity increased with time. In the pulse-chase experiment, the high molecular mass peaks (0.7–1.0 MDa) of both 14 C- and 3 H-polymers showed an extensive molecular mass downshift, but not the shoulder peak of 14 C-polymers. These results indicate that Xyloglucans in the fraction consist of two types of molecules; fucosylated high molecular mass polymers and non-fucosylated low molecular mass polymers. Azuki bean epicotyls may synthesize both types of Xyloglucans independently, but only fucosylated Xyloglucans undergo an active depolymerization in the cell wall.
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Role of xyloglucan in gravitropic bending of azuki bean epicotyl.
Physiologia Plantarum, 2008Co-Authors: Toshimitsu Ikushima, Kouichi Soga, Takayuki Hoson, Teruo ShimmenAbstract:The mechanism of the gravitropic bending was studied in azuki bean epicotyls. The cell wall extensibility of the lower side became higher than that of the upper side in the epicotyl bending upward. The contents of matrix polysaccharides of the cell wall (pectin and xyloglucan in hemicellulose-II) in the lower side became smaller than those in the upper side. The molecular mass of Xyloglucans in the lower side decreased. After an epicotyl was fixed to a metal rod to prevent the bending, gravistimulation was applied. Fundamentally the same results were obtained with respect to rheological and chemical characteristics of the cell wall as those of epicotyls showing gravitropic bending. The present results suggested that the initial gravitropic bending was caused by the increase in extensibility of the lower side and the decrease in extensibility of the upper side via the change of the cell wall matrix, especially Xyloglucans.
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stimulation of elongation growth and xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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gravitational force regulates elongation growth of arabidopsis hypocotyls by modifying xyloglucan metabolism
Advances in Space Research, 2001Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract:Abstract Growth of dark-grown Arabidopsis hypocotyls was suppressed under hypergravity conditions (300 g ), or was stimulated under microgravity conditions in space (Space Shuttle STS-95). The mechanical extensibility of cell walls decreased and increased under hypergravity and microgravity conditions, respectively. The amounts of cell wall polysaccharides (pectin, hemicellulose-I, hemicellulose-II and cellulose) per unit length of hypocotyls increased under hypergravity conditions, and decreased under microgravity conditions. The amount and the molecular mass of Xyloglucans also increased under the hypergravity conditions, while those decreased under microgravity conditions. The activity of xyloglucan-degrading enzymes extracted from hypocotyl cell walls decreased and increased under hypergravity and microgravity conditions, respectively. These results indicate that the amount and the molecular mass of Xyloglucans are affected by the magnitude of gravity and that such changes are caused by changes in xyloglucan-degrading activity. Modifications of xyloglucan metabolism as well as the thickness of cell walls by gravity stimulus may be the primary event determining the cell wall extensibility, thereby regulating the growth rate of Arabidopsis hypocotyls.
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Hypergravity Increases the Molecular Mass of Xyloglucans by Decreasing Xyloglucan-Degrading Activity in Azuki Bean Epicotyls
Plant and Cell Physiology, 1999Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract: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.
