Recombinant Silk Proteins with Additional Polyalanine Have Excellent Mechanical Properties

Area of Science:

• Biomaterials Engineering
• Synthetic Biology
• Materials Science

Background:

• Silkworm silk's mechanical properties are valuable but can be enhanced.
• Spider silk proteins, like MaSp1, possess superior strength characteristics.
• Genetic engineering offers a pathway to combine desirable protein traits.

Purpose of the Study:

• To investigate the structural integration of exogenous spider silk proteins into silkworm silk.
• To evaluate the impact of these engineered proteins on silk's mechanical properties.
• To provide a foundation for producing advanced bionic silk.

Main Methods:

• Construction of transgenic vectors combining silkworm fibroin light chain with MaSp1 (spider silk protein) variants.
• Generation of transgenic silkworms using piggyBac-mediated microinjection.
• Analysis of protein expression, structural conformation (FTIR, PONDR prediction), and mechanical properties (fracture strength, Young's modulus).

Main Results:

• Transgenic silkworms successfully produced and secreted foreign proteins within cocoons.
• Incorporation of MaSp1's type 3 repeats and polyalanine motifs increased beta-sheet content in silk.
• Increased beta-sheet content correlated with significantly improved fracture strength and Young's modulus.
• Longer chains of exogenous proteins led to enhanced mechanical performance.

Conclusions:

• Engineered silkworm silk with integrated spider silk proteins exhibits superior mechanical properties.
• The increased beta-sheet structure is key to the enhanced strength of the bionic silk.
• This study offers a viable strategy for the large-scale production of high-performance bionic silk.