Genetic hybridization of highly active exogenous functional proteins into silk-based materials using "light-clothing'' strategy

Genetic hybridization of exogenous functional protein(s) of interest (POI) with silk using transgenic silkworms provides promising biosynthesis platforms to design silk-based materials. To ensure successful hybridization, additive domains from natural silk are routinely fused with POI to form fusion POI (F-POI), but they often lead to superfluous post-translational modifications, compromise normal folding, and severely impair the activity of POI. Here, "light-clothing'' strategy, i.e., rationally trimming redundant parts of additive domains, is proposed. As visualized by green fluorescent protein as marker POI, this strategy avoids supernumerary post-translational modifications in F-POI synthesis, and enables its normal secretion and extraction. Applying epidermal growth factor as model functional POI, material fabrication versatility of the extracted mixture of F-POI and silk is demonstrated. This strategy increases structural similarity between F- POI and native POI and remarkably enhances F- POI activity to the same level as commercial POI, which facilitates applications of these advanced bio-synthesis platforms for developing high-performance materials.