Glycosyl transferase GT2 genes mediate the biosynthesis of an unusual (1,3;1,4)-β-glucan exopolysaccharide in the bacterium Sarcina ventriculi.

Linear, unbranched (1,3;1,4)-β-glucans (mixed-linkage glucans or MLGs) are commonly found in the cell walls of grasses, but have also been detected in basal land plants, algae, fungi and bacteria. Here we show that two family GT2 glycosyltransferases from the Gram-positive bacterium Sarcina ventriculi are capable of synthesizing MLGs. Immunotransmission electron microscopy demonstrates that MLG is secreted as an exopolysaccharide, where it may play a role in organizing individual cells into packets that are characteristic of Sarcina species.

The cellulose synthase-like F3 (CslF3) gene mediates cell wall polysaccharide synthesis and affects root growth and differentiation in barley.

The barley cellulose synthase-like F (CslF) genes encode putative cell wall polysaccharide synthases. They are related to the cellulose synthase (CesA) genes involved in cellulose biosynthesis, and the CslD genes that influence root hair development. Although CslD genes are implicated in callose, mannan and cellulose biosynthesis, and are found in both monocots and eudicots, CslF genes are specific to the Poaceae.

Analysis of Genetic Diversity in the Traditional Chinese Medicine Plant 'Kushen' ( Ait.).

Kushen root, from the woody legume , is a traditional Chinese medicine that is a key ingredient in several promising cancer treatments. This activity is attributed in part to two quinolizidine alkaloids (QAs), oxymatrine and matrine, that have a variety of therapeutic activities . Genetic selection is needed to adapt for cultivation and to improve productivity and product quality.

Overexpression of HvCslF6 in barley grain alters carbohydrate partitioning plus transfer tissue and endosperm development.

In cereal grain, sucrose is converted into storage carbohydrates: mainly starch, fructan, and mixed-linkage (1,3;1,4)-β-glucan (MLG). Previously, endosperm-specific overexpression of the HvCslF6 gene in hull-less barley was shown to result in high MLG and low starch content in mature grains. Morphological changes included inwardly elongated aleurone cells, irregular cell shapes of peripheral endosperm, and smaller starch granules of starchy endosperm.

A Novel (1,4)-β-Linked Glucoxylan Is Synthesized by Members of the Gene Family in Land Plants.

As a significant component of monocot cell walls, (1,3;1,4)-β-glucan has conclusively been shown to be synthesized by the cellulose synthase-like F6 protein. In this study, we investigated the synthetic activity of other members of the barley () gene family using heterologous expression. As expected, the majority of the genes encode proteins that are capable of synthesizing detectable levels of (1,3;1,4)-β-glucan.

Revised Phylogeny of the Gene Superfamily: Insights into Cell Wall Evolution.

Cell walls are crucial for the integrity and function of all land plants and are of central importance in human health, livestock production, and as a source of renewable bioenergy. Many enzymes that mediate the biosynthesis of cell wall polysaccharides are encoded by members of the large () gene superfamily. Here, we analyzed 29 sequenced genomes and 17 transcriptomes to revise the phylogeny of the gene superfamily in angiosperms.

Functional Characterization of a Glycosyltransferase from the Moss Involved in the Biosynthesis of a Novel Cell Wall Arabinoglucan.

Mixed-linkage (1,3;1,4)-β-glucan (MLG), an abundant cell wall polysaccharide in the Poaceae, has been detected in ascomycetes, algae, and seedless vascular plants, but not in eudicots. Although MLG has not been reported in bryophytes, a predicted glycosyltransferase from the moss (Pp3c12_24670) is similar to a bona fide ascomycete MLG synthase. We tested whether encodes an MLG synthase by expressing it in wild tobacco () and testing for release of diagnostic oligosaccharides from the cell walls by either lichenase or (1,4)-β-glucan endohydrolase.

Isolation and structural elucidation by 2D NMR of planteose, a major oligosaccharide in the mucilage of chia (Salvia hispanica L.) seeds.

An oligosaccharide was isolated in high purity and excellent yield from the water-extractable mucilage of chia (Salvia hispanica L.) seeds using an optimized solid-phase extraction method. LC-MS analysis showed that the compound presents a molecular mass of 504Da and trifluoroacetic acid hydrolysis revealed that it consists of galactose, glucose and fructose.

Differences in glycosyltransferase family 61 accompany variation in seed coat mucilage composition in Plantago spp.

Xylans are the most abundant non-cellulosic polysaccharide found in plant cell walls. A diverse range of xylan structures influence tissue function during growth and development. Despite the abundance of xylans in nature, details of the genes and biochemical pathways controlling their biosynthesis are lacking.

Prospecting for Energy-Rich Renewable Raw Materials: Sorghum Stem Case Study.

Sorghum vegetative tissues are becoming increasingly important for biofuel production. The composition of sorghum stem tissues is influenced by genotype, environment and photoperiod sensitivity, and varies widely between varieties and also between different stem tissues (outer rind vs inner pith). Here, the amount of cellulose, (1,3;1,4)-β-glucan, arabinose and xylose in the stems of twelve diverse sorghum varieties, including four photoperiod-sensitive varieties, was measured.

Structural Variation and Content of Arabinoxylans in Endosperm and Bran of Durum Wheat (Triticum turgidum L.).

Arabinoxylans are one group of dietary fiber components in cereal grains, and specific health benefits have been linked with their molecular fine structures and hence with physicochemical properties such as solubility in aqueous media. To characterize the fiber quality for functional foods, starchy endosperm and bran fractions from 11 durum wheat lines were analyzed for total and water-soluble arabinoxylans, (1,3;1,4)-β-glucan, and bound ferulic acid. The arabinoxylan contents ranged from 11 to 16.

(1,3;1,4)-β-Glucan Biosynthesis by the CSLF6 Enzyme: Position and Flexibility of Catalytic Residues Influence Product Fine Structure.

Cellulose synthase-like F6 (CslF6) genes encode polysaccharide synthases responsible for (1,3;1,4)-β-glucan biosynthesis in cereal grains. However, it is not clear how both (1,3)- and (1,4)-linkages are incorporated into a single polysaccharide chain and how the frequency and arrangement of the two linkage types that define the fine structure of the polysaccharide are controlled. Through transient expression in Nicotiana benthamiana leaves, two CSLF6 orthologs from different cereal species were shown to mediate the synthesis of (1,3;1,4)-β-glucans with very different fine structures.

Genetics, Transcriptional Profiles, and Catalytic Properties of the UDP-Arabinose Mutase Family from Barley.

Four members of the UDP-Ara mutase (UAM) gene family from barley have been isolated and characterized, and their map positions on chromosomes 2H, 3H, and 4H have been defined. When the genes are expressed in Escherichia coli, the corresponding HvUAM1, HvUAM2, and HvUAM3 proteins exhibit UAM activity, and the kinetic properties of the enzymes have been determined, including Km, Kcat, and catalytic efficiencies. However, the expressed HvUAM4 protein shows no mutase activity against UDP-Ara or against a broad range of other nucleotide sugars and related molecules.

Genetics and physiology of cell wall polysaccharides in the model C4 grass, Setaria viridis spp.

Background: Setaria viridis has emerged as a model species for the larger C4 grasses. Here the cellulose synthase (CesA) superfamily has been defined, with an emphasis on the amounts and distribution of (1,3;1,4)-β-glucan, a cell wall polysaccharide that is characteristic of the grasses and is of considerable value for human health.

Methods: Orthologous relationship of the CesA and Poales-specific cellulose synthase-like (Csl) genes among Setaria italica (Si), Sorghum bicolor (Sb), Oryza sativa (Os), Brachypodium distachyon (Bradi) and Hordeum vulgare (Hv) were compared using bioinformatics analysis.

Multiple-response optimization of the acidic treatment of the brown alga Ecklonia radiata for the sequential extraction of fucoidan and alginate.

The aim of this study was to optimize the acidic treatment of the brown alga Ecklonia radiata in order to extract fucoidan and facilitate the efficient sequential extraction of alginates. Response surface methodology was used to determine the effects of the temperature, pH, and duration of the acidic treatment on fucoidan yield, alginate extractability, and the molecular weight of sequentially extracted alginates. Desirability functions were then used to predict the best overall combinations of responses.

Prospecting for Energy-Rich Renewable Raw Materials: Agave Leaf Case Study.

Plant biomass from different species is heterogeneous, and this diversity in composition can be mined to identify materials of value to fuel and chemical industries. Agave produces high yields of energy-rich biomass, and the sugar-rich stem tissue has traditionally been used to make alcoholic beverages. Here, the compositions of Agave americana and Agave tequilana leaves are determined, particularly in the context of bioethanol production.

Distribution, structure and biosynthetic gene families of (1,3;1,4)-β-glucan in Sorghum bicolor.

In cereals, the presence of soluble polysaccharides including (1,3;1,4)-β-glucan has downstream implications for human health, animal feed and biofuel applications. Sorghum bicolor (L.) Moench is a versatile crop, but there are limited reports regarding the content of such soluble polysaccharides.

Separation and purification of soluble polymers and cell wall fractions from wheat, rye and hull less barley endosperm flours for structure-nutrition studies.

The nutritional values associated with the cell walls of cereal endosperm flours are due to a combination of solubilized arabinoxylan and (1-3,1-4)-β-d-glucan as well as residual nonsolubilized cell wall material. In order to investigate structure-nutrition relationships, an appropriate method for the complete functional and structural characterization of cell wall polysaccharides in various cereal endosperm flours is described. This involves the separation of soluble polymers and the residual cell wall fraction without using organic solvents, and the fractionation of soluble polymers into arabinoxylan- and (1-3,1-4)-β-d-glucan-rich fractions for subsequent analysis.

Analysis of the arabinoxylan arabinofuranohydrolase gene family in barley does not support their involvement in the remodelling of endosperm cell walls during development.

Arabinoxylan arabinofuranohydrolases (AXAHs) are family GH51 enzymes that have been implicated in the removal of arabinofuranosyl residues from the (1,4)-β-xylan backbone of heteroxylans. Five genes encoding barley AXAHs range in size from 4.6 kb to 7.

The genetics, transcriptional profiles, and catalytic properties of UDP-alpha-D-xylose 4-epimerases from barley.

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.

Substrate specificity and catalytic mechanism of a xyloglucan xyloglucosyl transferase HvXET6 from barley (Hordeum vulgare L.).

A family 16 glycoside hydrolase, xyloglucan xyloglucosyl transferase (EC 2.4.1.

A Barley xyloglucan xyloglucosyl transferase covalently links xyloglucan, cellulosic substrates, and (1,3;1,4)-beta-D-glucans.

Molecular interactions between wall polysaccharides, which include cellulose and a range of noncellulosic polysaccharides such as xyloglucans and (1,3;1,4)-beta-D-glucans, are fundamental to cell wall properties. These interactions have been assumed to be noncovalent in nature in most cases. Here we show that a highly purified barley xyloglucan xyloglucosyl transferase HvXET5 (EC 2.