Nucleotide sugar interconversions and cell wall biosynthesis: how to bring the inside to the outside

Seifert, Georg

doi:10.1016/j.pbi.2004.03.004

Cited by 294 publications

(242 citation statements)

References 52 publications

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“…Additive Percentage None 100 6 4 DTT (2 mM) 150 6 8 EDTA (2 mM) 9 5 6 2 MgCl 2 (1 mM) 101 6 2 NAD + (1 mM) 105 6 2 NADH (1 mM) 9 0 6 3 UMP (2 mM) 9 3 6 1 UDP (2 mM) 1 5 6 1 UTP (2 mM) 5 4 6 3 thesis of pentose-containing wall polysaccharides (Reiter and Vanzin, 2001;Seifert, 2004;Zhang et al, 2005). Furthermore, it is believed that a UDP-Ara mutase contributes to the composition of this pool through the conversion of UDP-Arap to UDP-Araf (Konishi et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…2). Comparisons with genome sequences that are now available for other members of the Poaceae reveal that rice (Oryza sativa), sorghum (Sorghum bicolor), and Brachypodium all contain at least three UXE genes, while Arabidopsis has four UXE genes (Reiter and Vanzin, 2001;Seifert, 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Oxidation of the UDP-Glc by UDP-D-Glc dehydrogenase forms UDP-D-glucuronate (UDP-GlcA), which is a glycosyl donor for the synthesis of glucuronoarabinoxylans. Following the epimerization of UDP-GlcA to UDP-D-GalUA, the latter acts as a sugar donor for pectic polysaccharide synthesis (Reiter and Vanzin, 2001;Seifert, 2004). The UDP-GlcA decarboxylases, also known as UDP-a-D-xylopyranose synthases (UXS), convert UDP-GlcA to UDP-Xyl (Zhang et al, 2005), which acts as the xylosyl donor not only for the biosynthesis of arabinoxylans but also for xyloglucans.…”

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The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

et al. 2010

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Cell walls in the grasses contain relatively high levels of heteroxylans and, in particular, arabinoxylans. Enzymes and corresponding genes that are involved in the provision of sugar nucleotide substrates represent potential control points for arabinoxylan biosynthesis. Following expressed sequence tag database analyses, three genes encoding barley (Hordeum vulgare) UDP-D-xylose 4-epimerases (UXE; EC 5.1.3.5), designated HvUXE1, HvUXE2, and HvUXE3, were cloned and their positions on genetic maps defined. To confirm the identity of the genes, a cDNA construct encoding HvUXE1 was expressed in Pichia pastoris. The purified, recombinant HvUXE1 catalyzed the freely reversible interconversion of UDP-a-D-xylopyranose and UDP-b-L-arabinopyranose, with K m values of 1.8 and 1.4 mM, respectively. At equilibrium, the ratio of substrate to product was approximately 1:1. Each molecule of heterologously expressed HvUXE1 enzyme contained about one molecule of noncovalently bound NAD + . Molecular modeling provided a structural rationale for the substrate specificity of the UDP-D-xylose 4-epimerase and, in particular, explained its tight specificity for UDP-xylose compared with other sugar nucleotide epimerases. Quantitative transcript analyses performed for each of the three genes in a range of organs showed, inter alia, that in developing barley endosperm HvUXE1 and HvUXE3 mRNA levels peaked at a time when UDP-a-D-xylopyranose synthase (UXS) transcripts also reached a maximum and when arabinoxylan biosynthesis was initiated. Furthermore, the data revealed that the transcription of HvUXE and HvUXS gene family members is coordinated with the incorporation of pentose sugars onto cell walls in barley leaves, roots, and developing endosperm.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

et al. 2010

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“…Based on the relative amounts of each polymer in the mature Arabidopsis cell wall and the monosaccharide composition thereof, one can calculate that roughly 50% of the cell-wall biomass (xylose, arabinose, apiose, glucuronic acid, and galacturonic acid) is derived from the precursor UDP-glucuronic acid (UDP-GlcA) through a complex nucleotide sugar interconversion pathway (Gibeaut 2000;Reiter and Vanzin 2001;Seifert 2004). This precursor is converted by an epimerase into UDP-galacturonic acid (Usadel et al 2004a;Mølhøj et al 2004), being an important precursor for pectic polymers.…”

Section: Introductionmentioning

confidence: 99%

The inositol oxygenase gene family of Arabidopsis is involved in the biosynthesis of nucleotide sugar precursors for cell-wall matrix polysaccharides

Kanter

Usadel

Guérineau

et al. 2005

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The nucleotide sugar UDP-glucuronic acid (UDP-GlcA) is the principal precursor for galacturonic acid, xylose, apiose and arabinose residues of the plant cell-wall polymers. UDP-GlcA can be synthesized by two different functional pathways in Arabidopsis involving either UDP-glucose dehydrogenase or inositol oxygenase as the initial enzyme reaction to channel carbohydrates into a pool of UDP sugars used for cellwall biosynthesis. The genes for the enzyme myo-inositol oxygenase (MIOX) were analyzed in Arabidopsis. They represent a small gene family containing four members. The transcription of all those members indicates a transient and organ-specific gene expression pattern in growing plant tissues as analyzed by RT-PCR and in promoter::GUS reporter gene lines. Two isoforms (MIOX1, MIOX2) are expressed in almost all tissues of the plant, whereas the expression of MIOX4 and MIOX5 is largely restricted to flowers, particularly maturing pollen. T-DNA insertion lines in MIOX genes were isolated; however, single knock-outs show growth phenotypes similar to the wild type. The monosaccharide composition of the cell wall in these mutants is not significantly changed compared to wild type plants. However, the incorporation of 3 H-inositol into wall polymers of seedlings is greatly impaired in the mutant lines DMIOX1 and DMIOX2, which are the only isoforms that are expressed in seedlings.

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“…sugars that are activated by the addition of UDP or GDP [2]. Most nucleotide sugars are synthesized in the cytosol from UDP-Glc, GDPMan or myo-inositol [3,4]. Therefore, the nucleotide sugars must be transported from the cytosol into the lumen of the ER and Golgi apparatus.…”

Section: Introductionmentioning

confidence: 99%

Characterization of AtNST‐KT1, a novel UDP‐galactose transporter from Arabidopsis thaliana

et al. 2006

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Nucleotide sugar transporters (NST) mediate the transfer of nucleotide sugars from the cytosol into the lumen of the endoplasmatic reticulum and the Golgi apparatus. Because the NSTs show similarities with the plastidic phosphate translocators (pPTs), these proteins were grouped into the TPT/NST superfamily. In this study, a member of the NST-KT family, AtNST-KT1, was functionally characterized by expression of the corresponding cDNA in yeast cells and subsequent transport experiments. The histidine-tagged protein was purified by affinity chromatography and reconstituted into proteoliposomes. The substrate specificity of AtNST-KT1 was determined by measuring the import of radiolabelled nucleotide mono phosphates into liposomes preloaded with various unlabelled nucleotide sugars. This approach has the advantage that only one substrate has to be used in a radioactively labelled form while all the nucleotide sugars can be provided unlabelled. It turned out that AtNST-KT1 represents a monospecific NST transporting UMP in counterexchange with UDP-Gal but did not transport other nucleotide sugars. The AtNST-KT1 gene is ubiquitously expressed in all tissues. AtNST-KT1 is localized to Golgi membranes. Thus, AtNST-KT1 is most probably involved in the synthesis of galactose-containing glyco-conjugates in plants.

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Nucleotide sugar interconversions and cell wall biosynthesis: how to bring the inside to the outside

Cited by 294 publications

References 52 publications

The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

The Genetics, Transcriptional Profiles, and Catalytic Properties of UDP-α-d-Xylose 4-Epimerases from Barley

The inositol oxygenase gene family of Arabidopsis is involved in the biosynthesis of nucleotide sugar precursors for cell-wall matrix polysaccharides

Characterization of AtNST‐KT1, a novel UDP‐galactose transporter from Arabidopsis thaliana

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