The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Maria J. Peña - One of the best experts on this subject based on the ideXlab platform.
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A Galacturonic Acid–Containing Xyloglucan Is Involved in Arabidopsis Root Hair Tip Growth
The Plant cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, William S. York, Malcolm A. O'neillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
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a Galacturonic Acid containing xyloglucan is involved in arabidopsis root hair tip growth
The Plant Cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, Malcolm A OneillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
Malcolm A. O'neill - One of the best experts on this subject based on the ideXlab platform.
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A Galacturonic Acid–Containing Xyloglucan Is Involved in Arabidopsis Root Hair Tip Growth
The Plant cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, William S. York, Malcolm A. O'neillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
Malcolm A Oneill - One of the best experts on this subject based on the ideXlab platform.
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a Galacturonic Acid containing xyloglucan is involved in arabidopsis root hair tip growth
The Plant Cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, Malcolm A OneillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
Yingzhen Kong - One of the best experts on this subject based on the ideXlab platform.
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A Galacturonic Acid–Containing Xyloglucan Is Involved in Arabidopsis Root Hair Tip Growth
The Plant cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, William S. York, Malcolm A. O'neillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
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a Galacturonic Acid containing xyloglucan is involved in arabidopsis root hair tip growth
The Plant Cell, 2012Co-Authors: Maria J. Peña, Yingzhen Kong, Malcolm A OneillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified xyloglucan that is composed of both neutral and Galacturonic Acid–containing subunits, the latter containing the β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic Acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no Acidic xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of xyloglucan that lacks Galacturonic Acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of Galacturonic Acid in the root xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no Acidic xyloglucan. However, overexpression of At1g63450 led to the synthesis of Galacturonic Acid–containing xyloglucan in these tissues. We propose that At1g63450 encodes XYLOGLUCAN-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic Acid-(1→2)-α-d-xylopyranosyl linkage and that the Acidic xyloglucan is present only in root hair cell walls. The role of the Acidic xyloglucan in root hair tip growth is discussed.
Peter Richard - One of the best experts on this subject based on the ideXlab platform.
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The introduction of the fungal D-galacturonate pathway enables the consumption of D-Galacturonic Acid by Saccharomyces cerevisiae.
Microbial cell factories, 2016Co-Authors: Alessandra Biz, Hannu Maaheimo, Maura Harumi Sugai-guérios, Joosu Kuivanen, Nadia Krieger, David A. Mitchell, Peter RichardAbstract:Pectin-rich wastes, such as citrus pulp and sugar beet pulp, are produced in considerable amounts by the juice and sugar industry and could be used as raw materials for biorefineries. One possible process in such biorefineries is the hydrolysis of these wastes and the subsequent production of ethanol. However, the ethanol-producing organism of choice, Saccharomyces cerevisiae, is not able to catabolize d-Galacturonic Acid, which represents a considerable amount of the sugars in the hydrolysate, namely, 18 % (w/w) from citrus pulp and 16 % (w/w) sugar beet pulp. In the current work, we describe the construction of a strain of S. cerevisiae in which the five genes of the fungal reductive pathway for d-Galacturonic Acid catabolism were integrated into the yeast chromosomes: gaaA, gaaC and gaaD from Aspergillus niger and lgd1 from Trichoderma reesei, and the recently described d-Galacturonic Acid transporter protein, gat1, from Neurospora crassa. This strain metabolized d-Galacturonic Acid in a medium containing d-fructose as co-substrate. This work is the first demonstration of the expression of a functional heterologous pathway for d-Galacturonic Acid catabolism in Saccharomyces cerevisiae. It is a preliminary step for engineering a yeast strain for the fermentation of pectin-rich substrates to ethanol.
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Engineering filamentous fungi for conversion of D-Galacturonic Acid to L-galactonic Acid.
Applied and environmental microbiology, 2012Co-Authors: Joosu Kuivanen, Peter Richard, Satu Hilditch, Merja Penttilä, Dominik Mojzita, Yanming Wang, Marilyn G. WiebeAbstract:d-Galacturonic Acid, the main monomer of pectin, is an attractive substrate for bioconversions, since pectin-rich biomass is abundantly available and pectin is easily hydrolyzed. l-Galactonic Acid is an intermediate in the eukaryotic pathway for d-Galacturonic Acid catabolism, but extracellular accumulation of l-galactonic Acid has not been reported. By deleting the gene encoding l-galactonic Acid dehydratase (lgd1 or gaaB) in two filamentous fungi, strains were obtained that converted d-Galacturonic Acid to l-galactonic Acid. Both Trichoderma reesei Δlgd1 and Aspergillus niger ΔgaaB strains produced l-galactonate at yields of 0.6 to 0.9 g per g of substrate consumed. Although T. reesei Δlgd1 could produce l-galactonate at pH 5.5, a lower pH was necessary for A. niger ΔgaaB. Provision of a cosubstrate improved the production rate and titer in both strains. Intracellular accumulation of l-galactonate (40 to 70 mg g biomass−1) suggested that export may be limiting. Deletion of the l-galactonate dehydratase from A. niger was found to delay induction of d-galacturonate reductase and overexpression of the reductase improved initial production rates. Deletion of the l-galactonate dehydratase from A. niger also delayed or prevented induction of the putative d-galacturonate transporter An14g04280. In addition, A. niger ΔgaaB produced l-galactonate from polygalacturonate as efficiently as from the monomer.
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Identification in Agrobacterium tumefaciens of the d-Galacturonic Acid dehydrogenase gene
Applied Microbiology and Biotechnology, 2010Co-Authors: Harry Boer, Hannu Maaheimo, Anu Koivula, Merja Penttilä, Peter RichardAbstract:There are at least three different pathways for the catabolism of d -galacturonate in microorganisms. In the oxidative pathway, which was described in some prokaryotic species, d -galacturonate is first oxidised to meso -galactarate (mucate) by a nicotinamide adenine dinucleotide (NAD)-dependent dehydrogenase (EC 1.1.1.203). In the following steps of the pathway mucate is converted to 2-keto-glutarate. The enzyme activities of this catabolic pathway have been described while the corresponding gene sequences are still unidentified. The d -galacturonate dehydrogenase was purified from Agrobacterium tumefaciens , and the mass of its tryptic peptides was determined using MALDI-TOF mass spectrometry. This enabled the identification of the corresponding gene udh . It codes for a protein with 267 amino Acids having homology to the protein family of NAD(P)-binding Rossmann-fold proteins. The open reading frame was functionally expressed in Saccharomyces cerevisiae . The N-terminally tagged protein was not compromised in its activity and was used after purification for a kinetic characterization. The enzyme was specific for NAD and accepted d -Galacturonic Acid and d -glucuronic Acid as substrates with similar affinities. NMR analysis showed that in water solution the substrate d -Galacturonic Acid is predominantly in pyranosic form which is converted by the enzyme to 1,4 lactone of galactaric Acid. This lactone seems stable under intracellular conditions and does not spontaneously open to the linear meso -galactaric Acid.
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d-Galacturonic Acid catabolism in microorganisms and its biotechnological relevance
Applied Microbiology and Biotechnology, 2009Co-Authors: Peter Richard, Satu HilditchAbstract:d -Galacturonic Acid is the main constituent of pectin, a naturally abundant compound. Pectin-rich residues accumulate when sugar is extracted from sugar beet or juices are produced from citrus fruits. It is a cheap raw material but currently mainly used as animal feed. Pectin has the potential to be an important raw material for biotechnological conversions to fuels or chemicals. In this paper, we review the microbial pathways for the catabolism of d- Galacturonic Acid that would be relevant for the microbial conversion to useful products.
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L-galactonate dehydratase is part of the fungal path for D-Galacturonic Acid catabolism.
Molecular microbiology, 2006Co-Authors: Satu Kuorelahti, Merja Penttilä, Hannu Maaheimo, Paula Jouhten, Peter RichardAbstract:An L-galactonate dehydratase and the corresponding gene were identified from the mould Hypocrea jecorina (Trichoderma reesei). This novel enzyme converts L-galactonate to L-threo-3-deoxy-hexulosonate (2-keto-3-deoxy-L-galactonate). The enzyme is part of the fungal pathway for D-Galacturonic Acid catabolism, a pathway which is only partly known. It is the second enzyme of this pathway after the D-Galacturonic Acid reductase. L-galactonate dehydratase activity is present in H. jecorina cells grown on D-Galacturonic Acid but absent when other carbon sources are used for growth. A deletion of the L-galactonate dehydratase gene in H. jecorina results in a strain with no growth on D-Galacturonic Acid. The active enzyme was produced in the heterologous host Saccharomyces cerevisiae and characterized. It exhibited activity with L-galactonate and D-arabonate where the hydroxyl group of the C2 is in L- and the hydroxyl group of the C3 is in D-configuration in the Fischer projection. However, it did not exhibit activity with D-galactonate, D-gluconate, L-gulonate or D-xylonate where the hydroxyl groups of the C2 and C3 are in different configuration.
