Engineered Large Spider Eggcase Silk Protein for Strong Artificial Fibers

A simple strategy is developed to produce large silk proteins in commercially available E. coli. The strategy is demonstrated for the production of a modified eggcase silk protein with a molecular weight of ∼378 kDa. Using a non-toxic water coagulation bath developed here, the recombinant protein is spun into artificial fibers that reach higher tenacity than its native counterpart. The strategy is generally applicable to synthesizing other types of large silk proteins with tandem repetitive domains.