Investigating the Atomic and Mesoscale Interactions that Facilitate Spider Silk Protein Pre-Assembly

Black widow spider dragline silk is one of nature's high-performance biological polymers, exceeding the strength and toughness of most man-made materials including high tensile steel and Kevlar. Major ampullate (Ma), or dragline silk, is primarily comprised of two spidroin proteins (Sp) stored within the Ma gland. In the native gland environment, the MaSp1 and MaSp2 proteins self-associate to form hierarchical 200-300 nm superstructures despite being intrinsically disordered proteins (IDPs). Here, dynamic light scattering (DLS), three-dimensional (3D) triple resonance solution NMR, and diffusion NMR is utilized to probe the MaSp size, molecular structure, and dynamics of these protein pre-assemblies diluted in 4 M urea and identify specific regions of the proteins important for silk protein pre-assembly. 3D NMR indicates that the Gly-Ala-Ala and Ala-Ala-Gly motifs flanking the poly(Ala) runs, which comprise the beta-sheet forming domains in fibers, are perturbed by urea, suggesting that these regions may be important for silk protein pre-assembly stabilization.

Automated summary

The dragline silk of the black widow spider is a high-performance biological polymer that exceeds the strength and toughness of man-made materials. The major ampullate silk is primarily composed of two spidroin proteins that self-associate to form superstructures despite being intrinsically disordered proteins. Research has shown that certain amino acid motifs play a crucial role in the pre-assembly of silk proteins.