Biology subjects

Dupree, R.

Publications and source records attributed to Dupree, R..

5 recordsLinked to original sources

bioRxiv2026

Preserving Native Cellulose-Xylan Architecture Enables Structure-Property Control in Holocellulose Nanofibrils and High-Performance Sustainable Materials

The hierarchical organization of cellulose microfibrils and their intimate interactions with hemicelluloses such as xylan underpin the exceptional mechanical performance of plant cell walls. However, translating these biological design principles into sustainable nanocellulosic materials remains limited by conventional cellulose nanofibril production routes, which rely on harsh chemical treatments that disrupt the native cellulose-hemicellulose architecture. Here, we present an optimized isolation strategy for holocellulose nanofibrils (hCNFs) that preserves native cellulose structure, xylan substitution and conformation, and cellulose-xylan interactions. Using wild-type Arabidopsis thaliana, a xylan glucuronidation-deficient gux1/2 mutant, and Brassica napus straw as model systems, we systematically elucidate how xylan content and substitution pattern govern nanofibril isolation, interfacial interactions, and macroscopic properties. Two-dimensional 13C magic-angle spinning NMR demonstrates retention of native cellulose glucosyl environments, the presence of two-fold and three-fold helical xylan conformations, and cellulose-associated two-fold helical xylan. Cryogenic transmission electron microscopy reveals fibril widths of [~]3 nm, consistent with elementary cellulose I{beta} microfibrils. We show that xylan glucuronidation regulates colloidal stability, hydration behavior, and interfibrillar cohesion, whereas xylan content controls nanofibrillation efficiency. These multiscale structural features translate directly into moisture sorption, thermal behavior, and mechanical performance. Notably, Brassica napus hCNF films exhibit exceptional strength and extensibility, surpassing many chemically modified CNF systems. This work demonstrates that preserving the native cellulose-hemicellulose architecture enables high-performance, sustainable nanocellulosic materials without chemical reconstruction.

biochemistry↗

bioRxiv2024

Glucomannan engineering highlights the role of galactosyl modification in fine-tuning cellulose-glucomannan interaction in Arabidopsis cell walls

Widely found in most plant lineages, {beta}-mannans are structurally diverse polysaccharides that can bind to cellulose fibrils to form the complex polysaccharide architecture of the cell wall. Glucomannan backbones acquire variable patterns of galactosyl substitutions, depending on plant developmental stage and species. How the changes in polysaccharide structure influence its cell wall solubility or promote appropriate interaction with cellulose fibrils is poorly understood. Here, we show that fine-tuning of galactosyl modification on glucomannans is achieved by the differing acceptor recognition of mannan -galactosyltransferases (MAGTs). Biochemical analysis and 13C solid-state nuclear magnetic resonance spectroscopy of Arabidopsis with cell wall glucomannan engineered by MAGTs revealed that the degree of galactosylation strongly affects the interaction with cellulose. The findings indicate that plants tailor galactosyl modification on glucomannans for constructing an appropriate cell wall architecture, paving the way to convert properties of lignocellulosic biomass for better use.

bioengineering↗

bioRxiv2024

New insights into the structure of cellulose in plant cell walls

The structure of plant cellulose microfibrils remains elusive, despite the abundance of cellulose and its utility in industry. Using 2D solid-state NMR of 13C labelled never-dried plants, six major glucose environments are resolved which are common to the cellulose of softwood, hardwood and grasses. These environments are maintained in isolated holo-cellulose nanofibrils, allowing more detailed microfibril characterisation. We show there are only two glucose environments that reside within the microfibril interior. These have the same NMR 13C chemical shifts as tunicate cellulose I{beta} centre and origin chains, with no cellulose I being detected. The third major glucose site with a carbon 4 chemical shift near 89 ppm, previously assigned to the crystalline microfibril interior, is now shown to be one of four surface glucose environments. The NMR peak widths of all four surface glucose environments are similar to those of the core indicating that their glucose local order is comparable; there is no significant amorphous cellulose in the microfibrils. Consequently, the ratio of the carbon 4 peaks at [~]89 and [~]84 ppm, which has often provided a sample cellulose crystallinity index, is not a meaningful measure of crystallinity or the interior to surface ratio. The revised ratio for poplar wood microfibrils is estimated to be 1:2, which is consistent with a cellulose I{beta} 18-chain microfibril having 6 core and 12 surface chains, although other microfibril sizes are possible. These advances change substantially both the interpretation of solid-state NMR studies of cellulose and the understanding of cellulose microfibril structure and crystallinity.

biochemistry↗

bioRxiv2022

Eudicot primary cell wall glucomannan is related in synthesis, structure and function to xyloglucan

The functional differences between plant cell wall hemicelluloses such as glucomannan, xylan and xyloglucan (XyG) remain unclear. These polysaccharides influence assembly and properties of the wall, perhaps by interacting with cellulose to affect the deposition and bundling of the fibrils. As the most abundant hemicellulose, XyG is considered important in eudicot primary cell walls (PCWs), but plants devoid of XyG show relatively mild phenotypes. We report here that a patterned {beta}-galactoglucomannan ({beta}-GGM) is widespread in PCW of eudicots and shows remarkable similarities to XyG. The sugar linkages forming the backbone and side chains of {beta}-GGM are analogous to those that make up XyG, and moreover, these linkages are formed by glycosyltransferases from the same CAZy families. Solid-state NMR indicated that {beta}-GGM shows low mobility in the cell wall, consistent with interaction with cellulose. Although Arabidopsis {beta}-GGM synthesis mutants show no obvious growth defects, genetic crosses between {beta}-GGM and XyG mutants produce exacerbated phenotypes compared to XyG mutants. These findings demonstrate a related role of these two similar but distinct classes of hemicelluloses in PCWs. This work will provide new avenues to study the roles of both {beta}-GGM and XyG in PCWs. One sentence summaryPatterned {beta}-GGM resembles xyloglucan in structure, biosynthesis and function.

plant biology↗

bioRxiv2021

Discovery of putative Golgi S-Adenosyl methionine transporters reveals the importance of plant cell wall polysaccharide methylation

Polysaccharide methylation, especially that of pectin, is a common and important feature of land plant cell walls. Polysaccharide methylation takes place in the Golgi apparatus and therefore relies on the import of S-adenosyl methionine (SAM) from the cytosol into the Golgi. However, to date, no Golgi SAM transporter has been identified in plants. In this work, we studied major facilitator superfamily members in Arabidopsis that we identified as putative Golgi SAM transporters (GoSAMTs). Knock-out of the two most highly expressed GoSAMTs led to a strong reduction in Golgi-synthesised polysaccharide methylation. Furthermore, solid-state NMR experiments revealed that reduced methylation changed cell wall polysaccharide conformations, interactions and mobilities. Notably, the NMR revealed the existence of pectin egg-box structures in intact cell walls, and showed that their formation is enhanced by reduced methyl-esterification. These changes in wall architecture were linked to substantial growth and developmental phenotypes. In particular, anisotropic growth was strongly impaired in the double mutant. The identification of putative transporters that import SAM into the Golgi lumen in plants provides new insights into the paramount importance of polysaccharide methylation for plant cell wall structure and function.

plant biology↗