No abstract

Growing plants with modified cell wall compositions is a promising strategy to improve resistance to pathogens, increase biomass digestibility, and tune other important properties. In order to alter biomass architecture, a detailed knowledge of cell wall structure and biosynthesis is a prerequisite. We report here a glycan array‐based assay for the high‐throughput identification and characterization of plant cell wall biosynthetic glycosyltransferases (GTs). We demonstrate that different heterologously expressed galactosyl‐, fucosyl‐, and xylosyltransferases can transfer azido‐functionalized sugar nucleotide donors to selected synthetic plant cell wall oligosaccharides on the array and that the transferred monosaccharides can be visualized “on chip” by a 1,3‐dipolar cycloaddition reaction with an alkynyl‐modified dye. The opportunity to simultaneously screen thousands of combinations of putative GTs, nucleotide sugar donors, and oligosaccharide acceptors will dramatically accelerate plant cell wall biosynthesis research.

Arabinogalactan proteins are heavily glycosylated proteoglycans in plants. Their glycan portion consists of type-II arabinogalactan polysaccharides whose heterogeneity hampers the assignment of the arabinogalactan protein function. Synthetic chemistry is key to the procurement of molecular probes for plant biologists. Described is the automated glycan assembly of 14 oligosaccharides from four monosaccharide building blocks. These linear and branched glycans represent key structural features of natural type-II arabinogalactans and will serve as tools for arabinogalactan biology.

We dissected halogen-aryl π interactions experimentally using a bicyclic N-arylimide based molecular torsion balances system, which is based on the influence of the non-bonded interaction on the equilibria between folded and unfolded states. Through comparison of balances modulated by higher halogens with fluorine balances, we determined the magnitude of the halogen-aryl π interactions in our unimolecular systems to be larger than -5.0 kJ mol , which is comparable with the magnitude estimated in the biomolecular systems. Our study provides direct experimental evidence of halogen-aryl π interactions in solution, which until now have only been revealed in the solid state and evaluated theoretically by quantum-mechanical calculations.

We report a traceless photocleavable linker for the automated glycan assembly of carbohydrates with free reducing ends. The reductive-labile functionality in the linker tolerates all commonly used reagents and protocols for automated glycan assembly, as demonstrated with the successful preparation of nine plant cell wall-related oligosaccharides, and is cleaved by hydrogenolysis.

Pectin is a structurally complex plant polysaccharide with many industrial applications in food products. The structural elucidation of pectin is aided by digestion assays with glycosyl hydrolases. We report the automated glycan assembly of oligosaccharides related to the arabinogalactan side chains of pectin as novel biochemical tools to determine the substrate specificities of endogalactanases. Analysis of the digestion products revealed different requirements for the lengths and arabinose substitution pattern of the oligosaccharides to be recognized and hydrolyzed by the galactanases.

The plant cell wall provides the richest available resource of fermentable carbohydrates and biobased materials. The main component of plant cell walls is cellulose, which is the most abundant biomolecule on earth. Apart from cellulose, which is constructed from relatively simple β‐1,4‐glucan chains, plant cell walls also contain structurally more complex heteropolysaccharides (hemicellulose and pectin), as well as lignin and cell‐wall proteins. A detailed understanding of the molecular structures, functions, and biosyntheses of cell‐wall components is required to further promote their industrial use. Plant cell‐wall research is, to a large degree, hampered by a lsack of available well‐defined oligosaccharide samples that represent the structural features of cell‐wall glycans. One technique to access these oligosaccharides is automated glycan assembly; a technique in which monosaccharide building blocks are, similarly to automated peptide and oligonucleotide chemistry, successively added to a linker‐functionalized resin in a fully automated manner. Herein, recent research into the automated glycan assembly of different classes of cell‐wall glycans used as molecular tools for cell‐wall biology is discussed. More than 60 synthetic oligosaccharides were prepared and printed as microarrays for screening monoclonal antibodies that recognize plant cell‐wall polysaccharides. The synthesized oligosaccharides have also been used to investigate glycosyltransferases and glycoside hydrolases, which are involved in synthesis and degradation of plant cell walls, as well as for the analysis of cell‐wall‐remodeling enzymes.

Growing plants with modified cell wall compositions is a promising strategy to improve resistance to pathogens, increase biomass digestibility, and tune other important properties. In order to alter biomass architecture, a detailed knowledge of cell wall structure and biosynthesis is a prerequisite. We report here a glycan array‐based assay for the high‐throughput identification and characterization of plant cell wall biosynthetic glycosyltransferases (GTs). We demonstrate that different heterologously expressed galactosyl‐, fucosyl‐, and xylosyltransferases can transfer azido‐functionalized sugar nucleotide donors to selected synthetic plant cell wall oligosaccharides on the array and that the transferred monosaccharides can be visualized “on chip” by a 1,3‐dipolar cycloaddition reaction with an alkynyl‐modified dye. The opportunity to simultaneously screen thousands of combinations of putative GTs, nucleotide sugar donors, and oligosaccharide acceptors will dramatically accelerate plant cell wall biosynthesis research.