Development And Optimization Of Automated Fibre Production For Recombinant Spider Wrapping Silk
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Spiders produce up to seven different types of silk, each serving different biological functions. Wrapping silk, used for wrapping of prey, is the toughest of the seven types. Limited information is available on wrapping silk fibre formation and structure. Native wrapping silk protein (AcSp1) in Argiope trifasciata consists of a core domain with at least 14 consecutive 200 amino acid repeat (“W”) units. A recombinant 3 W-unit protein (W3) was produced in Escherichia coli. Automated fibre production (“spinning”) was achieved by solubilization of W3 in two different solvent-based spinning “dopes”, followed by extrusion, dehydration, and post-spin stretching. Post-spin stretching improved fibre strength, enriched β-sheet conformation, and increased birefringence. Additionally, fibre extensibility differed with spinning dope composition, corresponding to differences in anisotropy of secondary structuring, and in birefringence. This high-throughput synthetic recombinant spider silk fibre production methodology will make possible studies of its atomic-level structuring using nuclear magnetic resonance spectroscopy.