Self-assembled semi-crystallinity at parallel β-sheet nanocrystal interfaces in clustered MaSp1 (spider silk)...

Area of Science:

• Biomaterials Science
• Protein Self-Assembly
• Computational Biophysics

Background:

• Spider silk proteins, particularly MaSp1, are known for their remarkable mechanical properties.
• The hierarchical structure of spider silk, involving crystalline and amorphous domains, is crucial for its strength.
• Understanding the self-assembly of these domains at the nanoscale is essential for biomaterial design.

Purpose of the Study:

• To model the self-assembly of semi-crystalline domains at beta-sheet nanocrystal interfaces in spider silk (MaSp1) proteins.
• To investigate the energetic factors governing the formation of semi-crystalline domains at these interfaces.
• To determine the relationship between interfacial stability and the structural characteristics of beta-sheet nanocrystals.

Main Methods:

• Utilized molecular dynamics simulations to model protein self-assembly.
• Focused on the interfaces between crystalline and amorphous domains within MaSp1 protein clusters.
• Analyzed the energetics and stability of these nanocrystal interfaces.

Main Results:

• Interfacial energetics between crystalline and amorphous domains effectively control the extent of semi-crystalline domain formation.
• Nanocrystal interface stability is not directly correlated with the bulk stability of the beta-sheet nanocrystal.
• Interfacial stability is highly sensitive to the length of polyalanine repeat units within beta-sheets.

Conclusions:

• The formation of semi-crystalline domains in spider silk is primarily governed by interfacial energetics.
• Optimal semi-crystallinity develops at interfaces with polyalanine beta-sheets of lengths comparable to those found in natural dragline silk.
• These findings provide insights into the structure-property relationships of spider silk and inform biomaterial design.