The interaction of xylosyltransferase and glucuronyltransferase involved in glucuronoxylan synthesis in pea (<i>Pisum sativum</i>) epicotyls

Baydoun, Elias; Waldron, Keith W.; Brett, Christopher T.

doi:10.1042/bj2570853

Cited by 48 publications

(39 citation statements)

References 17 publications

(17 reference statements)

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“…The elongation of the GX chain appears to require the cooperation of the transferases that catalyze the addition of xylose to the main chain and the addition of GlcA as a side chain (Baydoun et al, 1989). Thus, our observation that irx9 plants synthesize GX with reduced chain length could result from the disruption of either of these two processes.…”

Section: Irx9 Is Essential For the Normal Elongation Of Gx Chainsmentioning

confidence: 67%

“…Xylosyltransferase and glucuronyltransferase activities have been detected in numerous plants Northcote, 1981a, 1981b;Waldron and Brett, 1983;Baydoun et al, 1989;Suzuki et al, 1991;Porchia and Scheller, 2000;Kuroyama and Tsumuraya, 2001;Gregory et al, 2002). However, none of the genes encoding these enzymes has been identified, nor have any of the enzymes been purified to homogeneity and biochemically characterized.…”

Section: Introductionmentioning

confidence: 99%

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Arabidopsis irregular xylem8andirregular xylem9: Implications for the Complexity of Glucuronoxylan Biosynthesis

et al. 2007

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Mutations of Arabidopsis thaliana IRREGULAR XYLEM8 (IRX8) and IRX9 were previously shown to cause a collapsed xylem phenotype and decreases in xylose and cellulose in cell walls. In this study, we characterized IRX8 and IRX9 and performed chemical and structural analyses of glucuronoxylan (GX) from irx8 and irx9 plants. IRX8 and IRX9 are expressed specifically in cells undergoing secondary wall thickening, and their encoded proteins are targeted to the Golgi, where GX is synthesized. 1 H-NMR spectroscopy showed that the reducing end of Arabidopsis GX contains the glycosyl sequence 4-b-D-, which was previously identified in birch (Betula verrucosa) and spruce (Picea abies) GX. This indicates that the reducing end structure of GXs is evolutionarily conserved in woody and herbaceous plants. This sequence is more abundant in irx9 GX than in the wild type, whereas irx8 and fragile fiber8 (fra8) plants are nearly devoid of it. The number of GX chains increased and the GX chain length decreased in irx9 plants. Conversely, the number of GX chains decreased and the chain length heterodispersity increased in irx8 and fra8 plants. Our results suggest that IRX9 is required for normal GX elongation and indicate roles for IRX8 and FRA8 in the synthesis of the glycosyl sequence at the GX reducing end.

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Section: Irx9 Is Essential For the Normal Elongation Of Gx Chainsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Arabidopsis irregular xylem8andirregular xylem9: Implications for the Complexity of Glucuronoxylan Biosynthesis

et al. 2007

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“…Early biochemical studies revealed the activities of xylosyltransferases, glucuronosyltransferases, arabinosyltransferases, methyltransferases, and acetyltransferases that are likely involved in the biosynthesis of xylan (Baydoun et al, 1983(Baydoun et al, , 1989Kuroyama and Tsumuraya, 2001;Gregory et al, 2002;Porchia et al, 2002;Urahara et al, 2004;Zeng et al, 2008). However, none of the genes corresponding to these xylan biosynthetic enzymes have been identified.…”

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confidence: 99%

The Arabidopsis Family GT43 Glycosyltransferases Form Two Functionally Nonredundant Groups Essential for the Elongation of Glucuronoxylan Backbone

et al. 2010

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There exist four members of family GT43 glycosyltransferases in the Arabidopsis (Arabidopsis thaliana) genome, and mutations of two of them, IRX9 and IRX14, have previously been shown to cause a defect in glucuronoxylan (GX) biosynthesis. However, it is currently unknown whether IRX9 and IRX14 perform the same biochemical function and whether the other two GT43 members are also involved in GX biosynthesis. In this report, we performed comprehensive genetic analysis of the functional roles of the four Arabidopsis GT43 members in GX biosynthesis. The I9H (IRX9 homolog) and I14H (IRX14 homolog) genes were shown to be specifically expressed in cells undergoing secondary wall thickening, and their encoded proteins were targeted to the Golgi, where GX is synthesized. Overexpression of I9H but not IRX14 or I14H rescued the GX defects conferred by the irx9 mutation, whereas overexpression of I14H but not IRX9 or I9H complemented the GX defects caused by the irx14 mutation. Double mutant analyses revealed that I9H functioned redundantly with IRX9 and that I14H was redundant with IRX14 in their functions. In addition, double mutations of IRX9 and IRX14 were shown to cause a loss of secondary wall thickening in fibers and a much more severe reduction in GX amount than their single mutants. Together, these results provide genetic evidence demonstrating that all four Arabidopsis GT43 members are involved in GX biosynthesis and suggest that they form two functionally nonredundant groups essential for the normal elongation of GX backbone.

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“…Although xylan glucuronyltransferase activity (GuxT) has been detected in various plants (10,11,16,17), no strong candidate GTs for addition of GlcA or MeGlcA, collectively named [Me]GlcA, to the xylan backbone have yet been identified. Here, we show that gux mutants in two Golgi-localized putative GTs have reduced GlcA and MeGlcA substitution on GX in Arabidopsis stems.…”

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confidence: 99%

Absence of branches from xylan in Arabidopsis gux mutants reveals potential for simplification of lignocellulosic biomass

Mortimer

Miles

Brown

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

294

311

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As one of the most abundant polysaccharides on Earth, xylan will provide more than a third of the sugars for lignocellulosic biofuel production when using grass or hardwood feedstocks. Xylan is characterized by a linear β(1,4)-linked backbone of xylosyl residues substituted by glucuronic acid, 4-O-methylglucuronic acid or arabinose, depending on plant species and cell types. The biological role of these decorations is unclear, but they have a major influence on the properties of the polysaccharide. Despite the recent isolation of several mutants with reduced backbone, the mechanisms of xylan synthesis and substitution are unclear. We identified two Golgi-localized putative glycosyltransferases, GlucUronic acid substitution of Xylan (GUX)-1 and GUX2 that are required for the addition of both glucuronic acid and 4-O-methylglucuronic acid branches to xylan in Arabidopsis stem cell walls. The gux1 gux2 double mutants show loss of xylan glucuronyltransferase activity and lack almost all detectable xylan substitution. Unexpectedly, they show no change in xylan backbone quantity, indicating that backbone synthesis and substitution can be uncoupled. Although the stems are weakened, the xylem vessels are not collapsed, and the plants grow to normal size. The xylan in these plants shows improved extractability from the cell wall, is composed of a single monosaccharide, and requires fewer enzymes for complete hydrolysis. These findings have implications for our understanding of the synthesis and function of xylan in plants. The results also demonstrate the potential for manipulating and simplifying the structure of xylan to improve the properties of lignocellulose for bioenergy and other uses.bioenergy | glucuronoxylan | glycosyltransferase | plant cell wall | polysaccharide

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The interaction of xylosyltransferase and glucuronyltransferase involved in glucuronoxylan synthesis in pea (Pisum sativum) epicotyls

Cited by 48 publications

References 17 publications

Arabidopsis irregular xylem8andirregular xylem9: Implications for the Complexity of Glucuronoxylan Biosynthesis

Arabidopsis irregular xylem8andirregular xylem9: Implications for the Complexity of Glucuronoxylan Biosynthesis

The Arabidopsis Family GT43 Glycosyltransferases Form Two Functionally Nonredundant Groups Essential for the Elongation of Glucuronoxylan Backbone

Absence of branches from xylan in Arabidopsis gux mutants reveals potential for simplification of lignocellulosic biomass

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