Biology subjects

Deralia, P. K.

Publications and source records attributed to Deralia, P. K..

4 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↗

bioRxiv2025

The Carbohydrate Binding Module of TrCel7A Aids in Navigating the Complexity of Plant Cell Walls

Efficient enzymatic deconstruction of plant cell walls is critical for utilization of lignocellulose biomass. Key enzymes in this process are cellobiohydrolases, a class of cellulases that processively degrade crystalline cellulose. Many cellobiohydrolases possess a carbohydrate-binding module (CBM), yet the importance of CBMs in substrate interaction remains unclear. Here, we use single-molecule fluorescence microscopy to investigate how CBM1 of Trichoderma reesei Cel7A influences enzyme binding and motility on cellulose substrates of varying complexity. We compare wild-type Cel7A with a truncated variant lacking CBM1 (Cel7A{Delta}CBM) on bacterial cellulose (BC), phosphoric acid swollen cellulose (PASC), delignified milkweed cellulose (MWC), and holocellulose nanofibrils (hCNF). While both variants showed similar steady-state binding densities on BC and PASC, Cel7A{Delta}CBM exhibited reduced binding on MWC and hCNF, with the greatest reduction on the hemicellulose-rich hCNF. Alkali removal of hemicellulose partially restored Cel7A{Delta}CBM binding, suggesting a role for CBM1 in substrate navigation and productive binding sites recognition. Kinetic analyses revealed that CBM1 enables a rapid binding mode absent in the truncated variant. Comparisons with isolated CBM3 further showed that CBMs are capable of fast substrate association. These findings demonstrate that CBMs enhance cellulase-substrate interactions by accelerating binding, enabling navigation of the complex environment of plant cell walls. Our results emphasize the importance of CBMs in natural cellobiohydrolase function and highlight their value in the design of improved cellulases for industrial biomass conversion.

biochemistry↗

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↗

bioRxiv2023

Altering the substitution and crosslinking of glucuronoarabinoxylans affects cell wall porosity and assembly in Brachypodium distachyon.

O_LIThe Poaceae family of plants provides cereal crops that are critical for human and animal nutrition and also they are an important source of biomass. Interacting plant cell wall components give rise to recalcitrance to digestion, thus understanding the wall molecular architecture is important to improve biomass properties. Xylan is the main hemicellulose in grass cell walls. Recently, we reported structural variation in grass xylans, suggesting functional specialisation and distinct interactions with cellulose and lignin. Here, we investigated the functions of these xylans by perturbing the biosynthesis of specific xylan types. C_LIO_LIWe generated CRISPR/Cas9 knockout mutants in Brachypodium distachyon XAX1 and GUX2 genes involved in xylan biosynthesis. Using carbohydrate gel electrophoresis we identified biochemical changes in different xylan types. Saccharification, cryo-SEM, subcritical water extraction and ssNMR were used to study wall architecture. C_LIO_LIBdXAX1A and BdGUX2 enzymes modify different types of grass xylan. Brachypodium mutant walls are more porous, suggesting the xylan substitutions directed by both BdXAX1A andGUX2 enzymes influence xylan-xylan and/or xylan-lignin interactions. C_LIO_LISince xylan substitutions influence wall architecture and digestibility, our findings open new avenues to improve cereals for food and to use grass biomass for feed and the production of bioenergy and biomaterials. C_LI

biochemistry↗