A Core Structural Protein That Builds the Locust Mandible with a Mechanical Gradient

Area of Science:

• Biomaterials Science
• Structural Biology
• Insect Morphology

Background:

• Natural materials like locust mandibles exhibit mechanical gradients.
• These gradients are linked to specialized structural proteins (SPs) but formation mechanisms are unclear.

Purpose of the Study:

• To identify the mechanism behind SP chemical gradients in natural materials.
• To investigate the role of structural proteins in locust mandible formation.

Main Methods:

• Identification of a histidine-rich structural protein (LmMHSP) in locust mandibles.
• In vivo and in vitro experiments to determine LmMHSP functions.
• Analysis of chitin scaffold microstructures and their relation to SP gradients.

Main Results:

• LmMHSP acts as a core building block with multiple functions: chitin binding, matrix formation (via liquid-liquid phase separation), cross-linking, and metal coordination.
• The SP gradient originates from LmMHSP's chitin-binding activity and regional variations in chitin microstructure.
• Evidence supports LmMHSP's role in forming the mandible's mechanical properties.

Conclusions:

• The study elucidates the mechanism of SP chemical gradient formation in locust mandibles.
• LmMHSP's properties explain the material's mechanical gradients.
• Findings offer insights for biomimetic material fabrication.