Regular Motifs in Xylan Modulate Molecular Flexibility and Interactions with Cellulose Surfaces

Area of Science:

• Plant Biology
• Biochemistry
• Materials Science

Background:

• Secondary plant cell walls rely on interactions between cellulose, hemicelluloses (like xylan), and lignin for rigidity.
• The precise molecular details and nanoscale forces governing these interactions remain incompletely understood.

Purpose of the Study:

• To elucidate the substitution patterns of softwood xylans.
• To investigate how xylan's intramolecular motifs affect its conformation and interaction with cellulose surfaces.

Main Methods:

• Comprehensive mass spectrometric glycan sequencing.
• Molecular dynamics simulations.

Main Results:

• Confirmed xylan motifs with evenly spaced glycosyl decorations and minor consecutive glucuronations.
• Demonstrated that arabinofuranosyl decorations increase xylan flexibility.
• Showed that xylan substitutions enhance cellulose affinity and stabilize the 2-fold screw conformation, particularly on hydrophobic surfaces.

Conclusions:

• Xylan's molecular features significantly influence plant cell wall architecture.
• Nonpolar interactions play a key role in secondary cell wall structural integrity.
• Findings offer insights into lignocellulose recalcitrance and the development of wood-based materials.