19 results on '"Ulvskov, Peter"'
Search Results
2. Rhamnogalacturonan-I Based Microcapsules for Targeted Drug Release.
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Svagan AJ, Kusic A, De Gobba C, Larsen FH, Sassene P, Zhou Q, van de Weert M, Mullertz A, Jørgensen B, and Ulvskov P
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- Animals, Capsules chemistry, Drug Delivery Systems, Drug Liberation, Gastrointestinal Microbiome, Gastrointestinal Tract microbiology, Humans, Particle Size, Solanum tuberosum chemistry, Capsules chemical synthesis, Pectins pharmacokinetics
- Abstract
Drug targeting to the colon via the oral administration route for local treatment of e.g. inflammatory bowel disease and colonic cancer has several advantages such as needle-free administration and low infection risk. A new source for delivery is plant-polysaccharide based delivery platforms such as Rhamnogalacturonan-I (RG-I). In the gastro-intestinal tract the RG-I is only degraded by the action of the colonic microflora. For assessment of potential drug delivery properties, RG-I based microcapsules (~1 μm in diameter) were prepared by an interfacial poly-addition reaction. The cross-linked capsules were loaded with a fluorescent dye (model drug). The capsules showed negligible and very little in vitro release when subjected to media simulating gastric and intestinal fluids, respectively. However, upon exposure to a cocktail of commercial RG-I cleaving enzymes, ~ 9 times higher release was observed, demonstrating that the capsules can be opened by enzymatic degradation. The combined results suggest a potential platform for targeted drug delivery in the terminal gastro-intestinal tract., Competing Interests: The authors have declared that no competing interests exist.
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- 2016
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3. The structurally effect of surface coated rhamnogalacturonan I on response of the osteoblast-like cell line SaOS-2.
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Svava R, Gurzawska K, Yihau Y, Haugshøj KB, Dirscherl K, Levery SB, Jørgensen NR, Gotfredsen K, Damager I, Ulvskov P, and Jørgensen B
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- Cell Line, Cell Survival, Dental Implants, Humans, Lupinus chemistry, Malus chemistry, Coated Materials, Biocompatible chemistry, Osteoblasts cytology, Pectins chemistry
- Abstract
Osseointegration is important when implants are inserted into the bone and can be improved by biochemical surface coating of the implant. In this paper enzymatically modified rhamnogalacturonan I (RG-I) from apple and lupin was used for biochemical coating of aminated surfaces and the importance of the quality of RG-I, the nature of the binding, the fine structure of RG-I, and its effect on SaOS-2 cell line cultured on coated surfaces was investigated. SaOS-2 cells are osteoblast-like cells and a well-established in vitro model of bone-matrix forming osteoblasts. Purification by gel filtration could remove small fragments of galacturonic acid (GalA) and binding studies showed that the purity of the RG-I molecules was important for the quality of the coating. The structure of RG-I and osteoblast-like cells' viability were positively correlated so that high content of 1,4-linked galactose (Gal) and a low content of arabinose in the RG-I molecules favored cell viability. These results indicate that coating of implants with RG-I affect osseointegration positively., (Copyright © 2013 Wiley Periodicals, Inc.)
- Published
- 2014
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4. Pectic arabinan side chains are essential for pollen cell wall integrity during pollen development.
- Author
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Cankar K, Kortstee A, Toonen MA, Wolters-Arts M, Houbein R, Mariani C, Ulvskov P, Jorgensen B, Schols HA, Visser RG, and Trindade LM
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- Chromosome Segregation, Crosses, Genetic, Gene Dosage, Monosaccharides metabolism, Phenotype, Plant Infertility genetics, Plant Tubers cytology, Plant Tubers metabolism, Plants, Genetically Modified, Pollen anatomy & histology, Pollen ultrastructure, Solanum tuberosum genetics, Solanum tuberosum ultrastructure, Transformation, Genetic, Transgenes genetics, Cell Wall metabolism, Pectins metabolism, Pollen cytology, Pollen growth & development, Polysaccharides metabolism, Solanum tuberosum cytology
- Abstract
Pectin is a complex polysaccharide and an integral part of the primary plant cell wall and middle lamella, contributing to cell wall mechanical strength and cell adhesion. To understand the structure-function relationships of pectin in the cell wall, a set of transgenic potato lines with altered pectin composition was analysed. The expression of genes encoding enzymes involved in pectin acetylation, degradation of the rhamnogalacturonan backbone and type and length of neutral side chains, arabinan and galactan in particular, has been altered. Upon crossing of different transgenic lines, some transgenes were not transmitted to the next generation when these lines were used as a pollen donor, suggesting male sterility. Viability of mature pollen was severely decreased in potato lines with reduced pectic arabinan, but not in lines with altered galactan side chains. Anthers and pollen of different developmental stages were microscopically examined to study the phenotype in more detail. Scanning electron microscopy of flowers showed collapsed pollen grains in mature anthers and in earlier stages cytoplasmic protrusions at the site of the of kin pore, eventually leading to bursting of the pollen grain and leaking of the cytoplasm. This phenomenon is only observed after the microspores are released and the tapetum starts to degenerate. Timing of the phenotype indicates a role for pectic arabinan side chains during remodelling of the cell wall when the pollen grain is maturing and dehydrating., (© 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.)
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- 2014
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5. Effect of nanocoating with rhamnogalacturonan-I on surface properties and osteoblasts response.
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Gurzawska K, Svava R, Syberg S, Yihua Y, Haugshøj KB, Damager I, Ulvskov P, Christensen LH, Gotfredsen K, and Jørgensen NR
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- Animals, Cell Line, Coated Materials, Biocompatible metabolism, Humans, Lupinus chemistry, Malus chemistry, Materials Testing, Microscopy, Atomic Force, Molecular Structure, Osseointegration, Osteoblasts cytology, Pectins metabolism, Photoelectron Spectroscopy, Surface Properties, Coated Materials, Biocompatible chemistry, Nanostructures chemistry, Osteoblasts physiology, Pectins chemistry, Prostheses and Implants
- Abstract
Long-term stability of titanium implants are dependent on a variety of factors. Nanocoating with organic molecules is one of the methods used to improve osseointegration. Therefore, the aim of this study is to evaluate the in vitro effect of nanocoating with pectic rhamnogalacturonan-I (RG-I) on surface properties and osteoblasts response. Three different RG-Is from apple and lupin pectins were modified and coated on amino-functionalized tissue culture polystyrene plates (aminated TCPS). Surface properties were evaluated by scanning electron microscopy, contact angle measurement, atomic force microscopy, and X-ray photoelectron spectroscopy. The effects of nanocoating on proliferation, matrix formation and mineralization, and expression of genes (real-time PCR) related to osteoblast differentiation and activity were tested using human osteoblast-like SaOS-2 cells. It was shown that RG-I coatings affected the surface properties. All three RG-I induced bone matrix formation and mineralization, which was also supported by the finding that gene expression levels of alkaline phosphatase, osteocalcin, and collagen type-1 were increased in cells cultured on the RG-I coated surface, indicating a more differentiated osteoblastic phenotype. This makes RG-I coating a promising and novel candidate for nanocoatings of implants., (Copyright © 2011 Wiley Periodicals, Inc.)
- Published
- 2012
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6. Affecting osteoblastic responses with in vivo engineered potato pectin fragments.
- Author
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Kokkonen H, Verhoef R, Kauppinen K, Muhonen V, Jørgensen B, Damager I, Schols HA, Morra M, Ulvskov P, and Tuukkanen J
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- Animals, Carbohydrates analysis, Cell Differentiation drug effects, Cell Proliferation drug effects, Chromatography, Gel, Focal Adhesions drug effects, Focal Adhesions metabolism, Mice, Microscopy, Confocal, Osteoblasts cytology, Plants, Genetically Modified, Reverse Transcriptase Polymerase Chain Reaction, Genetic Engineering, Osteoblasts drug effects, Osteoblasts metabolism, Pectins pharmacology, Solanum tuberosum genetics, Solanum tuberosum metabolism
- Abstract
Pectins, complex plant-derived polysaccharides, are novel candidates for biomaterial nanocoatings. Pectic rhamnogalacturonan-I regions (RG-I) can be enzymatically treated to so-called modified hairy regions (MHR). We surveyed the growth and differentiation of murine preosteoblastic MC3T3-E1 cells on Petri dishes coated with RG-Is from native or genetically engineered potato tubers. Uncoated tissue culture polystyrene (TCPS) and aminated (AMI) dishes served as controls. MHRPTR_GAL sample was depleted of galactose (9 mol % galactose; 23 mol % arabinose) and MHRPTR_ARA of arabinose (61 mol % galactose; 6 mol % arabinose). Wild-type (modified hairy region from potato pectin (MHRP)_WT) fragment contained default amounts (58 mol % galactose; 13 mol % arabinose) of both sugars. Focal adhesions (FAs) indicating cellular attachment were quantified. Reverse transcriptase polymerase chain reaction (RT-PCR) of alkaline phosphatase and osteocalcin genes indicating osteoblastic differentiation was performed along with staining the produced calcium with tetracycline as an indicator of osteoblastic differentiation. Osteoblasts proliferated on all the samples to some extent. The control surfaces performed better than any of the pectin samples, of which the MHRP_WT seemed to function best. FA length was greater on MHRPTR_GAL than on other pectin samples, otherwise the mutants did not significantly deviate. RT-PCR results indicate that differences between the samples at the gene expression level might be even subtler. However, tetracycline-stained calcium-containing mineral was detected merely only on uncoated TCPS. These results indicate the possibility to affect bone cell growth with in vivo-modified pectin fragments, consecutively providing information on the significance of certain monosaccharides on the biocompatibility of these polysaccharides., (Copyright © 2011 Wiley Periodicals, Inc.)
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- 2012
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7. Residue specific hydration of primary cell wall potato pectin identified by solid-state 13C single-pulse MAS and CP/MAS NMR spectroscopy.
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Larsen FH, Byg I, Damager I, Diaz J, Engelsen SB, and Ulvskov P
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- Carbon Isotopes, Cell Wall chemistry, Magnetic Resonance Spectroscopy methods, Pectins chemistry, Solanum tuberosum chemistry, Water chemistry
- Abstract
Hydration of rhamnogalacturonan-I (RG-I) derived from potato cell wall was analyzed by (13)C single-pulse (SP) magic-angle-spinning (MAS) and (13)C cross-polarization (CP) MAS nuclear magnetic resonance (NMR) and supported by (2)H SP/MAS NMR experiments. The study shows that the arabinan side chains hydrate more readily than the galactan side chains and suggests that the overall hydration properties can be controlled by modifying the ratio of these side chains. Enzymatic modification of native (NA) RG-I provided samples with reduced content of arabinan (sample DA), galactan (sample DG), or both side chains (sample DB). Results of these samples suggested that hydration properties were determined by the length and character of the side chains. NA and DA exhibited similar hydration characteristics, whereas DG and DB were difficult to hydrate because of the less hydrophilic properties of the rhamnose-galacturonic acid (Rha-GalA) backbone in RG-I. Potential food ingredient uses of RG-I by tailoring of its structure are discussed.
- Published
- 2011
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8. Simultaneous in vivo truncation of pectic side chains.
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Obro J, Borkhardt B, Harholt J, Skjøt M, Willats WG, and Ulvskov P
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- Arabidopsis enzymology, Galactans metabolism, Pectins chemistry, Plants, Genetically Modified enzymology, Plants, Genetically Modified genetics, Polysaccharide-Lyases genetics, Polysaccharides metabolism, Arabidopsis genetics, Pectins metabolism, Polysaccharide-Lyases metabolism
- Abstract
Despite the wide occurrence of pectin in nature only a few source materials have been used to produce commercial pectins. One of the reasons for this is that many plant species contain pectins with high levels of neutral sugar side chains or that are highly substituted with acetyl or other groups. These modifications often prevent gelation, which has been a major functional requirement of commercial pectins until recently. We have previously shown that modification of pectin is possible through heterologous expression of pectin degrading enzymes in planta. To test the effect of simultaneous modification of the two main neutral pectic side chains in pectic rhamnogalacturonan I (RGI), we constitutively expressed two different enzymes in Arabidopsis thaliana that would either modify the galactan or the arabinan side chains, or both side chains simultaneously. Our analysis showed that the simultaneous truncation of arabinan and galactan side chains is achievable and does not severely affect the growth of Arabidopsis thaliana.
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- 2009
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9. Functional characterisation of a putative rhamnogalacturonan II specific xylosyltransferase.
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Egelund J, Damager I, Faber K, Olsen CE, Ulvskov P, and Petersen BL
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- Arabidopsis genetics, Arabidopsis Proteins classification, Arabidopsis Proteins genetics, Cloning, Molecular, Fucose metabolism, Genes, Plant, Pentosyltransferases classification, Pentosyltransferases genetics, Phylogeny, Pichia genetics, Substrate Specificity, UDP Xylose-Protein Xylosyltransferase, Arabidopsis enzymology, Arabidopsis Proteins metabolism, Pectins metabolism, Pentosyltransferases metabolism
- Abstract
An Arabidopsis thaliana gene, At1g56550, was expressed in Pichia pastoris and the recombinant protein was shown to catalyse transfer of D-xylose from UDP-alpha-D-xylose onto methyl alpha-L-fucoside. The product formed was shown by 1D and 2D 1H NMR spectroscopy to be Me alpha-D-Xyl-(1,3)-alpha-L-Fuc, which is identical to the proposed target structure in the A-chain of rhamnogalacturonan II. Chemically synthesized methyl L-fucosides derivatized by methyl groups on either the 2-, 3- or 4 position were tested as acceptor substrates but only methyl 4-O-methyl-alpha-L-fucopyranoside acted as an acceptor, although to a lesser extent than methyl alpha-L-fucoside. At1g56550 is suggested to encode a rhamnogalacturonan II specific xylosyltransferase.
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- 2008
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10. Arabidopsis thaliana RGXT1 and RGXT2 encode Golgi-localized (1,3)-alpha-D-xylosyltransferases involved in the synthesis of pectic rhamnogalacturonan-II.
- Author
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Egelund J, Petersen BL, Motawia MS, Damager I, Faik A, Olsen CE, Ishii T, Clausen H, Ulvskov P, and Geshi N
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- Amino Acid Sequence, Animals, Arabidopsis Proteins chemistry, Arabidopsis Proteins metabolism, Baculoviridae genetics, Base Sequence, DNA Primers, Insecta, Isoenzymes chemistry, Isoenzymes metabolism, Molecular Sequence Data, Pentosyltransferases chemistry, Pentosyltransferases metabolism, Reverse Transcriptase Polymerase Chain Reaction, Sequence Homology, Amino Acid, Substrate Specificity, UDP Xylose-Protein Xylosyltransferase, Arabidopsis Proteins genetics, Golgi Apparatus enzymology, Isoenzymes genetics, Pectins biosynthesis, Pentosyltransferases genetics
- Abstract
Two homologous plant-specific Arabidopsis thaliana genes, RGXT1 and RGXT2, belong to a new family of glycosyltransferases (CAZy GT-family-77) and encode cell wall (1,3)-alpha-d-xylosyltransferases. The deduced amino acid sequences contain single transmembrane domains near the N terminus, indicative of a type II membrane protein structure. Soluble secreted forms of the corresponding proteins expressed in insect cells showed xylosyltransferase activity, transferring d-xylose from UDP-alpha-d-xylose to l-fucose. The disaccharide product was hydrolyzed by alpha-xylosidase, whereas no reaction was catalyzed by beta-xylosidase. Furthermore, the regio- and stereochemistry of the methyl xylosyl-fucoside was determined by nuclear magnetic resonance to be an alpha-(1,3) linkage, demonstrating the isolated glycosyltransferases to be (1,3)-alpha-d-xylosyltransferases. This particular linkage is only known in rhamnogalacturonan-II, a complex polysaccharide essential to vascular plants, and is conserved across higher plant families. Rhamnogalacturonan-II isolated from both RGXT1 and RGXT2 T-DNA insertional mutants functioned as specific acceptor molecules in the xylosyltransferase assay. Expression of RGXT1- and RGXT2-enhanced green fluorescent protein constructs in Arabidopsis revealed that both fusion proteins were targeted to a Brefeldin A-sensitive compartment and also colocalized with the Golgi marker dye BODIPY TR ceramide, consistent with targeting to the Golgi apparatus. Taken together, these results suggest that RGXT1 and RGXT2 encode Golgi-localized (1,3)-alpha-d-xylosyltransferases involved in the biosynthesis of pectic rhamnogalacturonan-II.
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- 2006
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11. Biophysical consequences of remodeling the neutral side chains of rhamnogalacturonan I in tubers of transgenic potatoes.
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Ulvskov P, Wium H, Bruce D, Jørgensen B, Qvist KB, Skjøt M, Hepworth D, Borkhardt B, and Sørensen SO
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- Kinetics, Pectins chemistry, Rheology, Species Specificity, Water metabolism, Pectins metabolism, Plant Roots physiology, Plants, Genetically Modified physiology
- Abstract
Two lines of transgenic potato (Solanum tuberosum L.) plants modified in their cell wall structure were characterized and compared to wild type with regard to biomechanical properties in order to assign functional roles to the particular cell wall polysaccharides that were targeted by the genetic changes. The targeted polymer was rhamnogalacturonan I (RG-I), a complex pectic polysaccharide comprised of mainly neutral oligosaccharide side chains attached to a backbone of alternating rhamnosyl and galacturonosyl units. Tuber rhamnogalacturonan I molecules from the two transformed lines are reduced in linear galactans and branched arabinans, respectively. The transformed tuber tissues were found to be more brittle when subjected to uniaxial compression and the side-chain truncation was found to be correlated with the physical properties of the tissue. Interpretation of the force-deflection curves was aided by a mathematical model that describes the contribution of the cellulose microfibrils, and the results lead to the proposition that the pectic matrix plays a role in transmitting stresses to the load-bearing cellulose microfibrils and that even small changes to the rheological properties of the matrix have consequences for the biophysical properties of the wall.
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- 2005
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12. Effects on interfacial properties and cell adhesion of surface modification by pectic hairy regions.
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Morra M, Cassinelli C, Cascardo G, Nagel MD, Della Volpe C, Siboni S, Maniglio D, Brugnara M, Ceccone G, Schols HA, and Ulvskov P
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- Animals, Biophysical Phenomena, Biophysics, Biotechnology, Carbohydrate Sequence, Cell Adhesion, Culture Techniques, Electron Probe Microanalysis, Fibroblasts cytology, Hexuronic Acids chemistry, Humans, Macromolecular Substances chemistry, Mice, Microscopy, Atomic Force, Molecular Sequence Data, Myocytes, Smooth Muscle cytology, Polysaccharides chemistry, Polystyrenes chemistry, Spectrophotometry, Infrared, Surface Properties, Time Factors, Water chemistry, Pectins chemistry
- Abstract
Polystyrene Petri dishes, aminated by a plasma deposition process, were surface modified by the covalent linking of two different enzymatically modified hairy regions (HRs) from pectin containing, for example, rhamnogalacturonan-I and xylogalacturonan structural elements. The two polysaccharide preparations share the same structural elements of apple pectin, but the relative amounts and lengths of the neutral side chains present differ. Surface analysis by X-ray photoelectron spectroscopy, contact angle measurement, and atomic force microscope (AFM) force-separation curves was used to characterize the effects on surface chemistry and interfacial forces of the surface modification process. Cell adhesion experiments using continuous L-929 fibroblasts and primary aortic smooth muscle cells were performed to evaluate the effect of the polysaccharide nature on cell adhesion. Results show that immobilization of the HR affects the interfacial field of forces and the cell behavior: "equilibrium" contact angles, obtained by a recently introduced vibrational approach, decrease after HR immobilization reaching a value close to 20 degrees . AFM force-separation curves show a more extended (or softer) interface in the case of the HR bearing longer side chains. Accordingly, depending on the HR preparation, cells shifted from spread morphology and adhesion behavior quantitatively comparable to that observed on conventional tissue culture polystyrene to rounded morphology and significantly lower adhesion. These data show that engineering of plant pectins can be a valuable tool to prepare novel and finely tuned polysaccharides having different chemico-physical and biological properties, to be used in the surface modification of medical devices and materials.
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- 2004
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13. Subcellular localization and topology of beta(1-->4)galactosyltransferase that elongates beta(1-->4)galactan side chains in rhamnogalacturonan I in potato.
- Author
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Geshi N, Jørgensen B, and Ulvskov P
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- Blotting, Western, Detergents pharmacology, Endopeptidase K pharmacology, Galactans chemistry, Golgi Apparatus drug effects, Octoxynol pharmacology, Polyethylene Glycols pharmacology, Pyrophosphatases metabolism, Sucrose metabolism, Galactans metabolism, Golgi Apparatus enzymology, N-Acetyllactosamine Synthase metabolism, Pectins biosynthesis, Solanum tuberosum enzymology
- Abstract
The subcellular localization and topology of rhamnogalacturonan I (RG-I) beta(1-->4)galactosyltransferase(s) (beta[1-->4]GalTs) from potato ( Solanum tuberosum L.) were investigated. Using two-step discontinuous sucrose step gradients, galactosyltransferase (GalT) activity that synthesized 70%-methanol-insoluble products from UDP-[(14)C]Gal was detected in both the 0.5 M sucrose fraction and the 0.25/1.1 M sucrose interface. The former fraction contained mainly soluble proteins and the latter was enriched in Golgi vesicles that contained most of the UDPase activity, a Golgi marker. By gel-filtration analysis, products of 180-2000 Da were found in the soluble fraction, whereas in the Golgi-enriched fraction the products were larger than 80 kDa and could be digested with rhamnogalacturonan lyase and beta(1,4) endogalactanase to yield smaller rhamnogalacturonan oligomers, galactobiose and galactose. The endogalactanase requires beta(1-->4)galactans with at least three galactosyl residues for cleavage, indicating that the enzyme(s) present in the 0.25/1.1 M Suc interface transferred one or more galactosyl residues to pre-existing beta(1-->4)galactans producing RG-I side chains in total longer than a trimer. Thus, the beta(1-->4)GalT activity that elongates beta(1-->4)-linked galactan on RG-I was located in the Golgi apparatus. This beta(1-->4)GalT activity was not reduced after treatment of the Golgi vesicles with proteinase, but approximately 75% of the activity was lost after treatment with proteinase in the presence of Triton X-100. In addition, the beta(1-->4)GalT activity was recovered in the detergent phase after treatment of Golgi vesicles with Triton X-114. Taken together, these observations supported the view that the RG-I beta(1-->4)GalT that elongates beta(1-->4)galactan was mainly located in the Golgi apparatus and integrated into the membrane with its catalytic site facing the lumen.
- Published
- 2004
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14. If homogalacturonan were a side chain of rhamnogalacturonan I. Implications for cell wall architecture.
- Author
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Vincken JP, Schols HA, Oomen RJ, McCann MC, Ulvskov P, Voragen AG, and Visser RG
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- Biopolymers chemistry, Molecular Structure, Cell Wall chemistry, Pectins chemistry
- Published
- 2003
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15. In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side-chains and abnormal periderm development.
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Oomen RJ, Doeswijk-Voragen CH, Bush MS, Vincken JP, Borkhardt B, van den Broek LA, Corsar J, Ulvskov P, Voragen AG, McCann MC, and Visser RG
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- Aspergillus enzymology, Cell Wall metabolism, Cell Wall ultrastructure, Microscopy, Confocal, Microscopy, Electron, Plant Stems growth & development, Plants, Genetically Modified, Polysaccharide-Lyases genetics, Polysaccharide-Lyases metabolism, Solanum tuberosum genetics, Solanum tuberosum growth & development, Galactans metabolism, Pectins metabolism, Plant Stems enzymology, Polysaccharides metabolism, Solanum tuberosum enzymology
- Abstract
Rhamnogalacturonan (RG) I is a branched pectic polysaccharide in plant cell walls. Rhamnogalacturonan lyase (eRGL) from Aspergillus aculeatus is able to cleave the RG I backbone at specific sites. Transgenic potato (Solanum tuberosum L.) plants were made by the introduction of the gene encoding eRGL, under the control of the granule-bound starch synthase promoter. The eRGL protein was successfully expressed and translated into an active form, demonstrated by eRGL activity in the tuber extracts. The transgenic plants produced tubers with clear morphological alterations, including radial swelling of the periderm cells and development of intercellular spaces in the cortex. Sugar compositional analysis of the isolated cell walls showed a large reduction in galactosyl and arabinosyl residues in transgenic tubers. Immunocytochemical studies using the LM5 (galactan) and LM6 (arabinan) antibodies also showed a large reduction in galactan and arabinan side-chains of RG I. Most of the remaining LM5 epitopes were located in the expanded middle lamella at cell corners of eRGL tubers, which is in contrast to their normal location in the primary wall of wild type tubers. These data suggest that RG I has an important role in anchoring galactans and arabinans at particular regions in the wall and in normal development of the periderm.
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- 2002
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16. Direct interference with rhamnogalacturonan I biosynthesis in Golgi vesicles.
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Skjøt M, Pauly M, Bush MS, Borkhardt B, McCann MC, and Ulvskov P
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- Cell Wall metabolism, Gene Expression Regulation, Enzymologic, Glycoside Hydrolases genetics, Glycoside Hydrolases metabolism, Pectins antagonists & inhibitors, Plant Proteins genetics, Plant Proteins metabolism, Plants, Genetically Modified, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Sialyltransferases genetics, Sialyltransferases metabolism, Solanum tuberosum enzymology, Golgi Apparatus metabolism, Pectins biosynthesis, Solanum tuberosum genetics
- Abstract
Pectin is a class of complex cell wall polysaccharides with multiple roles during cell development. Assigning specific functions to particular polysaccharides is in its infancy, in part, because of the limited number of mutants and transformants available with modified pectic polymers in their walls. Pectins are also important polymers with diverse applications in the food and pharmaceutical industries, which would benefit from technology for producing pectins with specific functional properties. In this report, we describe the generation of potato (Solanum tuberosum L. cv Posmo) tuber transformants producing pectic rhamnogalacturonan I (RGI) with a low level of arabinosylation. This was achieved by the expression of a Golgi membrane-anchored endo-alpha-1,5-arabinanase. Sugar composition analysis of RGI isolated from transformed and wild-type tubers showed that the arabinose content was decreased by approximately 70% in transformed cell walls compared with wild type. The modification of the RGI was confirmed by immunolabeling with an antibody recognizing alpha-1,5-arabinan. This is the first time, to our knowledge, that the biosynthesis of a plant cell wall polysaccharide has been manipulated through the action of a glycosyl hydrolase targeted to the Golgi compartment.
- Published
- 2002
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17. Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties.
- Author
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Orfila, Caroline, Degan, Florence, Jørgensen, Bodil, Scheller, Henrik, Ray, Peter, and Ulvskov, Peter
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PECTINS ,MUNG bean ,TUBERS ,POTATOES ,ACETYLATION ,PLANT cells & tissues - Abstract
A mung bean ( Vigna radiata) pectin acetyl esterase (CAA67728) was heterologously expressed in tubers of potato ( Solanum tuberosum) under the control of the granule-bound starch synthase promoter or the patatin promoter in order to probe the significance of O-acetylation on cell wall and tissue properties. The recombinant tubers showed no apparent macroscopic phenotype. The enzyme was recovered from transgenic tubers using a high ionic strength buffer and the extract was active against a range of pectic substrates. Partial in vivo de-acetylation of cell wall polysaccharides occurred in the transformants, as shown by a 39% decrease in the degree of acetylation (DA) of tuber cell wall material (CWM). Treatment of CWM using a combination of endo-polygalacturonase and pectin methyl esterase extracted more pectin polymers from the transformed tissue compared to wild type. The largest effect of the pectin acetyl esterase (68% decrease in DA) was seen in the residue from this extraction, suggesting that the enzyme is preferentially active on acetylated pectin that is tightly bound to the cell wall. The effects of acetylation on tuber mechanical properties were investigated by tests of failure under compression and by determination of viscoelastic relaxation spectra. These tests suggested that de-acetylation resulted in a stiffer tuber tissue and a stronger cell wall matrix, as a result of changes to a rapidly relaxing viscoelastic component. These results are discussed in relation to the role of pectin acetylation in primary cell walls and its implications for industrial uses of potato fibres. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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18. Erratum to: Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties.
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Orfila, Caroline, Degan, Florence, Jørgensen, Bodil, Scheller, Henrik, Ray, Peter, and Ulvskov, Peter
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PECTINS ,TUBERS - Abstract
A correction to the article "Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties" is presented.
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- 2012
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19. Characterisation of the arabinose-rich carbohydrate composition of immature and mature marama beans (Tylosema esculentum)
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Mosele, Minah M., Hansen, Åse S., Engelsen, Søren B., Diaz, Jerome, Sørensen, Iben, Ulvskov, Peter, Willats, William G.T., Blennow, Andreas, and Harholt, Jesper
- Subjects
- *
BEANS , *CARBOHYDRATES , *LEGUMES , *STARCH , *PLANT cell walls , *PECTINS , *ORGANIC compounds , *MANNOSE - Abstract
Abstract: Marama bean (Tylosema esculentum) is an important component of the diet around the Kalahari Desert in Southern Africa where this drought resistant plant can grow. The marama bean contains roughly 1/3 proteins, 1/3 lipids and 1/3 carbohydrates, but despite its potential as dietary supplement little is known about the carbohydrate fraction. In this study the carbohydrate fraction of “immature” and “mature” marama seeds are characterised. The study shows that the marama bean contains negligible amounts of starch and soluble sugars, both far less than 1%. The cell wall is characterised by a high arabinose content and a high resistance to extraction as even a 6M NaOH extraction was insufficient to extract considerable amounts of the arabinose. The arabinose fraction was characterised by arabinan-like linkages and recognised by the arabinan antibody LM6 and LM13 indicating that it is pectic arabinan. Two pools of pectin could be detected; a regular CDTA (1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid) or enzymatically extractable pectin fraction and a recalcitrant pectin fraction containing the majority of the arabinans, of which about 40% was unextractable using 6M NaOH. Additionally, a high content of mannose was observed, possibly from mannosylated storage proteins. [Copyright &y& Elsevier]
- Published
- 2011
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