A plant mutase that interconverts UDP-arabinofuranose and UDP-arabinopyranose

Konishi, Teruko; Takeda, Takumi; Miyazaki, Yasumasa; Ohnishi‐Kameyama, Mayumi; Hayashi, Takahisa; O’Neill, Malcolm A.; Ishii, Tadashi

doi:10.1093/glycob/cwl081

Cited by 131 publications

(161 citation statements)

References 36 publications

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“…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%

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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“…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%

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

et al. 2010

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“…xylan backbone extension and addition of Araf and GlcA sugars to the backbone) was shown to contain three wheat proteins that were homologous to the GT43 IRX14, the GT47 IRX10, and a GT75 protein (Zeng et al, 2010). This GT75 protein is orthologous to OsUAM1 and presumably has the same UDP-Ara mutase activity found for the protein in rice (Konishi et al, 2007), converting the supplied UDPArap into the UDP-Araf found in the products. Since the observed xylan GlcA transferase activity is retaining and the three identified proteins are all from inverting families, other active proteins must be present.…”

mentioning

confidence: 98%

RNA Interference Suppression of Genes in Glycosyl Transferase Families 43 and 47 in Wheat Starchy Endosperm Causes Large Decreases in Arabinoxylan Content

et al. 2013

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The cell walls of wheat (Triticum aestivum) starchy endosperm are dominated by arabinoxylan (AX), accounting for 65% to 70% of the polysaccharide content. Genes within two glycosyl transferase (GT) families, GT43 (IRREGULAR XYLEM9 [IRX9] and IRX14) and GT47 (IRX10), have previously been shown to be involved in the synthesis of the xylan backbone in Arabidopsis, and close homologs of these have been implicated in the synthesis of xylan in other species. Here, homologs of IRX10 TaGT47_2 and IRX9 TaGT43_2, which are highly expressed in wheat starchy endosperm cells, were suppressed by RNA interference (RNAi) constructs driven by a starchy endosperm-specific promoter. The total amount of AX was decreased by 40% to 50% and the degree of arabinosylation was increased by 25% to 30% in transgenic lines carrying either of the transgenes. The cell walls of starchy endosperm in sections of grain from TaGT43_2 and TaGT47_2 RNAi transgenics showed decreased immunolabeling for xylan and arabinoxylan epitopes and approximately 50% decreased cell wall thickness compared with controls. The proportion of AX that was water soluble was not significantly affected, but average AX polymer chain length was decreased in both TaGT43_2 and TaGT47_2 RNAi transgenics. However, the long AX chains seen in controls were absent in TaGT43_2 RNAi transgenics but still present in TaGT47_2 RNAi transgenics. The results support an emerging picture of IRX9-like and IRX10-like proteins acting as key components in the xylan synthesis machinery in both dicots and grasses. Since AX is the main component of dietary fiber in wheat foods, the TaGT43_2 and TaGT47_2 genes are of major importance to human nutrition.

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“…15 RGPs subsequently have been isolated from several other plant species including maize 11 Arabidopsis 12,22 wheat 23 and rice. 24 However, the role of RGPs in b-1,4-glucan synthesis remains unclear. Given their Golgi localization and glycosylation activity, RGPs have been implicated in polysaccharide biosynthesis, particularly cell wall and starch synthesis.…”

Section: Nbrgps Function In Regulating Pd-mediated Intercellular Tranmentioning

confidence: 99%

Reduced levels of class 1 reversibly glycosylated polypeptide increase intercellular transport via plasmodesmata

Burch‐Smith

Cui

Zambryski

2012

Plant Signaling & Behavior

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Maize and Arabidopsis thaliana class 1 reversibly glycosylated polypeptides ( C1 RGPs) are plasmodesmata-associated proteins. Previously, overexpression of Arabidopsis C1 RGP AtRGP2 in Nicotiana tabacum was shown to reduce intercellular transport of photoassimilate, resulting in stunted, chlorotic plants, and inhibition of local cell-to-cell spread of tobacco mosaic virus (TMV). Here, we used virus induced gene silencing to examine the effects of reduced levels of Plasmodesmata Structure and FunctionPlasmodesmata (PD) are membrane-lined cytoplasmic channels that connect contiguous plants cells, allowing transport of water, solutes, ions, nucleic acids and proteins between cells (for review see refs. 1-2). The importance of plasmodesmata to plant growth and development is demonstrated by the early lethality of mutants with altered PD structure and function.3,4 Electron microscopy reveals that PD consist largely of membranes and spaces (for review see ref. 5). Plasma membrane spans the cell wall between adjacent cells to form the outer limits of a given PD channel, and the ER of the adjacent two cells is continuous through the axial center of the channel, forming a specialized structure called the desmotubule (DT). Transport through PD is thought to predominantly occur in the space between the plasma membrane and DT, called the cytoplasmic sleeve, 6 while plant viruses also move along the membranes of the DT 7 and small molecules (~3 kDa) may move cell-to-cell via the lumen of the DT.

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A plant mutase that interconverts UDP-arabinofuranose and UDP-arabinopyranose

Cited by 131 publications

References 36 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

RNA Interference Suppression of Genes in Glycosyl Transferase Families 43 and 47 in Wheat Starchy Endosperm Causes Large Decreases in Arabinoxylan Content

Reduced levels of class 1 reversibly glycosylated polypeptide increase intercellular transport via plasmodesmata

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