Structural insights into polysaccharides in Ganoderma lucidum cell walls by solid-state NMR

Area of Science:

• Biochemistry
• Mycology
• Structural Biology

Background:

• Ganoderma lucidum, a medicinal mushroom, is valued in traditional Asian medicine.
• It possesses over 400 bioactive compounds, notably polysaccharides (GLPs), known for diverse biological functions.
• The precise molecular arrangement of GLPs within the fungal cell wall is not well understood.

Purpose of the Study:

• To elucidate the molecular architecture of Ganoderma lucidum polysaccharides (GLPs) within the cell wall.
• To characterize the structural and dynamic properties of GLPs using advanced spectroscopic techniques.

Main Methods:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy for non-destructive structural analysis.
• Proton-driven spin-diffusion (PDSS) experiments to identify intermolecular contacts.
• Hydration-kinetics measurements to assess component hydrophilicity/hydrophobicity.

Main Results:

• A rigid core scaffold of β-1,3-glucan, chitin, and chitosan was identified.
• A more mobile outer layer rich in β-1,4-glucan, α-glucans, and various sugars was revealed.
• Significant intermolecular contacts between β-1,3-glucan and chitin were detected, with chitosan exhibiting dynamic mobility.

Conclusions:

• Ganoderma lucidum's cell wall features a layered structure with distinct mechanical properties.
• β-1,3-glucan and chitin interactions likely provide mechanical strength.
• Chitosan's flexibility may facilitate adaptive cell wall remodeling.